Patent Application
20230318346
The subject matter described herein relates generally to systems, devices, and methods for pulse charging and pulse heating of rechargeable energy sources.
Electrical energy storage systems are an important facet in the worldwide transition to cleaner forms of energy. Electrical energy storage systems are found in a host of stationary and mobile applications. An electrical energy storage system in the form of a pack can be used to power hybrid and fully electric vehicles, and can be used to store power generated by the vehicle (e.g., through the use of regenerative braking). Electrical energy storage systems can be located in stacks or racks and used to store and supply energy for residential, commercial, and industrial facilities and can be integrated with or used to form grids and microgrids.
These energy storage systems (ESSs) require periodic charging to replenish the discharged power. A number of deficiencies and problems associated with existing charging methods have been identified, such as thermal losses, degradation, and slow rate of charge. For example, lengthy charge times for electric vehicles (EVs) are a major factor limiting their wide spread acceptance. Use of a conventional constant current charging method can take multiple hours to fully charge a battery pack. Such long wait times create substantial inconvenience and inefficiency when using EVs for travel outside the range of one charge for the EV. As such, conventional EVs are most typically used for local commuting, or trips that can be completed without requiring a recharge of the battery pack. To the extent charge stations capable of charging at higher voltage in less time exist, repeated use of such stations can result in dramatically reduced lifetime of the battery pack.
The negative impact of slow charge times is not limited to EVs, as systems adapted for use in stationary applications can also benefit. Further, any device relying on a battery pack for supplying power can potentially benefit, such as power tools, drones, and remote controlled vehicles.
The response of batteries, such as lithium ion batteries, to charging is dependent on the temperature of the battery. If a lithium ion battery is charged and too high of an anode or cathode overvoltage is applied while still at a relatively low temperature, then the battery can be severely degraded. This can lead to failures from phenomena such as lithium plating within the power cell.
For these and other reasons, needs exist for improved systems, devices, and methods for fast charging and/or heating of energy sources.
Example embodiments of systems, devices, and methods are described herein for fast charging of energy sources in isolation or as part of an energy storage system (e.g., a battery pack of an electric vehicle, a stationary system energy buffer, a microgrid, and others). The embodiments described herein can include heating an energy source through application of a preheating signal that raises the source temperature and lowers the overall impedance of the energy source such that accelerated electrochemical reactions are possible through subsequent charging. The embodiments can include charging an energy source with charge pulses at a frequency that passes a double sheet capacitance of the energy source and reduces an activation impedance of the source, permitting charging of the source at higher rates without degradatory reactions. The embodiments can also include a combination of a pulse preheating phase or a pulse charging phase with a constant current (or non-pulsed) charging phase at higher temperatures, and embodiments can include at least one instance of all three phases. The embodiments described herein are particularly suitable for application within cascaded modular energy storage systems where each module includes at least one energy source and switch circuitry capable of applying current in a pulsed manner for preheating and/or charging.
Embodiments are described for assessing one or more parameters of an energy source to be charged and utilizing the assessed parameter(s) in selecting a setting for performance of a heating and/or charging protocol. The parameter can be measured by the system, or based on a prior measurement or representative value stored in memory (local or remote) and retrieved by the system. Examples of parameters can include impedance, inductance, and thermal characteristics. Examples of settings can relate to frequency, voltage, current, or timing of a heating or charging signal.
Embodiments are described for assessing voltage changes that occur due to concentration shifts in the energy source resulting from charging. The assessed voltage changes can be utilized as real time feedback for adjusting the charging process. For example, the assessed voltage can be an activation overvoltage due to concentration shift, and can be utilized as feedback to adjust charge current (or voltage) limits to avoid exceeding a permissible anode overvoltage (and any accompanying detrimental effects).
Other systems, devices, methods, features and advantages of the subject matter described herein will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the subject matter described herein, and be protected by the accompanying claims. In no way should the features of the example embodiments be construed as limiting the appended claims, absent express recitation of those features in the claims.
The details of the subject matter set forth herein, both as to its structure and operation, may be apparent by study of the accompanying figures, in which like reference numerals refer to like parts. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the subject matter. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.
Before the present subject matter is described in detail, it is to be understood that this disclosure is not limited to the particular embodiments described, as such may, of course, vary. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.
Before describing the example embodiments pertaining to heating and/or charging energy systems, it is first useful to describe a class of energy systems that can be used with the example embodiments in greater detail. With reference to
Stationary applications are those in which the modular energy system is located in a fixed location during use, although it may be capable of being transported to alternative locations when not in use. The module-based energy system resides in a static location while providing electrical energy for consumption by one or more other entities, or storing or buffering energy for later consumption. Examples of stationary applications in which the embodiments disclosed herein can be used include, but are not limited to: energy systems for use by or within one or more residential structures or locales, energy systems for use by or within one or more industrial structures or locales, energy systems for use by or within one or more commercial structures or locales, energy systems for use by or within one or more governmental structures or locales (including both military and non-military uses), energy systems for charging the mobile applications described below (e.g., a charge source or a charging station), and systems that convert solar power, wind, geothermal energy, fossil fuels, or nuclear reactions into electricity for storage. Stationary applications often supply loads such as grids and microgrids, motors, and data centers. A stationary energy system can be used in either a storage or non-storage role.
Mobile applications, sometimes referred to as traction applications, are generally ones where a module-based energy system is located on or within an entity, and stores and provides electrical energy for conversion into motive force by a motor to move or assist in moving that entity. Examples of mobile entities with which the embodiments disclosed herein can be used include, but are not limited to, electric and/or hybrid entities that move over or under land, over or under sea, above and out of contact with land or sea (e.g., flying or hovering in the air), or through outer space. Examples of mobile entities with which the embodiments disclosed herein can be used include, but are not limited to, vehicles, trains, trams, ships, vessels, aircraft, and spacecraft. Examples of mobile vehicles with which the embodiments disclosed herein can be used include, but are not limited to, those having only one wheel or track, those having only two-wheels or tracks, those having only three wheels or tracks, those having only four wheels or tracks, and those having five or more wheels or tracks. Examples of mobile entities with which the embodiments disclosed herein can be used include, but are not limited to, a car, a bus, a truck, a motorcycle, a scooter, an electric bicycle, an industrial vehicle, a mining vehicle, a flying vehicle (e.g., a plane, a helicopter, a drone, etc.), a maritime vessel (e.g., commercial shipping vessels, ships, yachts, boats or other watercraft), a submarine, a locomotive or rail-based vehicle (e.g., a train, a tram, etc.), a military vehicle, a spacecraft, and a satellite.
Portable power applications include applications where a device that is portable by a human, and thus relatively smaller than a stationary ESS or an EV, receives power from one or more energy sources. Portable devices are generally powered by one or more battery power cells, typically lithium ion, though not so limited. Examples of portable devices can include power tools and professional grade video cameras, portable power stations, mobile phones, headsets, and wearable electronic devices.
In describing embodiments herein, reference may be made to a particular stationary application (e.g., grid, micro-grid, data centers, cloud computing environments), mobile application (e.g., an electric car), or portable power application. Such references are made for ease of explanation and do not mean that a particular embodiment is limited for use to only that particular application. Embodiments of systems providing power to a motor can be used in mobile, stationary, and portable power applications. While certain configurations may be more suitable to some applications over others, all example embodiments disclosed herein are capable of use in both mobile and stationary applications unless otherwise noted.
Conventional systems using one or more batteries can have those batteries arranged in an energy storage assembly in a variety of configurations. For example the energy storage assembly can be relatively small, such as a battery with only a single cell or a battery module having multiple cells connected together in a hardwired (e.g., non-switchable) serial and/or parallel configuration, or can be larger and more complex, such as multiple battery modules (each having multiple cells) connected together in a hardwired (e.g., non-switchable) serial and/or parallel configuration (like a conventional EV battery pack). These assembly configurations are typically charged by applying a DC voltage to the assembly as a whole. In the pulse charging and pulse heating embodiments described herein, voltage or current can be applied to these assembly configurations in a pulse manner to achieve desirable effects such as reduced charge time and temperature control. Pulsing can be performed through the addition of new switch circuitry between the charge source and the energy storage assembly, e.g., either in the charge source or in the system or device having the assembly, or through the use of switch circuitry already present (e.g., an inverter).
The embodiments described herein can be also be used with energy storage systems having cascaded or distributed AC-DC converters, e.g., where each battery module has a discrete converter associated therewith, and an applied DC charge current or power can be pulsed individually for each battery module. Examples of these and other energy storage systems are described in the following section with reference to system 100.
System 100 is configured to supply power to load 101. Load 101 can be any type of load such as a motor or a grid. System 100 is also configured to store power received from a charge source.
Control system 102 can be configured as a single device (e.g.,
Control system 102 can be configured to execute control using software (instructions stored in memory that are executable by processing circuitry), hardware, or a combination thereof. The one or more devices of control system 102 can each include processing circuitry 120 and memory 122 as shown here. Example implementations of processing circuitry and memory are described further below.
Control system 102 can have a communicative interface for communicating with devices 104 external to system 100 over a communication link or path 105. For example, control system 102 (e.g., MCD 112) can output data or information about system 100 to another control device 104 (e.g., the Electronic Control Unit (ECU) or Motor Control Unit (MCU) of a vehicle in a mobile application, grid controller in a stationary application, etc.).
Communication paths or links 105, 106, 115, 116, and 118 (
Control system 102 is configured to control one or more modules 108 based on status information received from the same or different one or more of modules 108. Control can also be based on one or more other factors, such as requirements of load 101. Controllable aspects include, but are not limited to, one or more of voltage, current, phase, and/or output power of each module 108.
Status information of every module 108 in system 100 can be communicated to control system 102, which can independently control every module 108-1 . . . 108-N. Other variations are possible. For example, a particular module 108 (or subset of modules 108) can be controlled based on status information of that particular module 108 (or subset), based on status information of a different module 108 that is not that particular module 108 (or subset), based on status information of all modules 108 other than that particular module 108 (or subset), based on status information of that particular module 108 (or subset) and status information of at least one other module 108 that is not that particular module 108 (or subset), or based on status information of all modules 108 in system 100.
The status information can be information about one or more aspects, characteristics, or parameters of each module 108. Types of status information include, but are not limited to, the following aspects of a module 108 or one or more components thereof (e.g., energy source, energy buffer, converter, monitor circuitry): State of Charge (SOC) (e.g., the level of charge of an energy source relative to its capacity, such as a fraction or percent) of the one or more energy sources of the module, State of Health (SOH) (e.g., a figure of merit of the condition of an energy source compared to its ideal conditions) of the one or more energy sources of the module, temperature of the one or more energy sources or other components of the module, capacity of the one or more energy sources of the module, voltage of the one or more energy sources and/or other components of the module, current of the one or more energy sources and/or other components of the module, State of Power (SOP) (e.g., the available power limitation of the energy source during discharge and/or charge), State of Energy (SOE) (e.g., the present level of available energy of an energy source relative to the maximum available energy of the source), and/or the presence of absence of a fault in any one or more of the components of the module.
LCDs 114 can be configured to receive the status information from each module 108, or determine the status information from monitored signals or data received from or within each module 108, and communicate that information to MCD 112. In some embodiments, each LCD 114 can communicate raw collected data to MCD 112, which then algorithmically determines the status information on the basis of that raw data. MCD 112 can then use the status information of modules 108 to make control determinations accordingly. The determinations may take the form of instructions, commands, or other information (such as a modulation index described herein) that can be utilized by LCDs 114 to either maintain or adjust the operation of each module 108.
For example, MCD 112 may receive status information and assess that information to determine a difference between at least one module 108 (e.g., a component thereof) and at least one or more other modules 108 (e.g., comparable components thereof). For example, MCD 112 may determine that a particular module 108 is operating with one of the following conditions as compared to one or more other modules 108: with a relatively lower or higher SOC, with a relatively lower or higher SOH, with a relatively lower or higher capacity, with a relatively lower or higher voltage, with a relatively lower or higher current, with a relatively lower or higher temperature, or with or without a fault. In such examples, MCD 112 can output control information that causes the relevant aspect (e.g., output voltage, current, power, temperature) of that particular module 108 to be reduced or increased (depending on the condition). In this manner, the utilization of an outlier module 108 (e.g., operating with a relatively lower SOC or higher temperature), can be reduced so as to cause the relevant parameter of that module 108 (e.g., SOC or temperature) to converge towards that of one or more other modules 108.
The determination of whether to adjust the operation of a particular module 108 can be made by comparison of the status information to predetermined thresholds, limits, or conditions, and not necessarily by comparison to statuses of other modules 108. The predetermined thresholds, limits, or conditions can be static thresholds, limits, or conditions, such as those set by the manufacturer that do not change during use. The predetermined thresholds, limits, or conditions can be dynamic thresholds, limits, or conditions, that are permitted to change, or that do change, during use. For example, MCD 112 can adjust the operation of a module 108 if the status information for that module 108 indicates it to be operating in violation (e.g., above or below) of a predetermined threshold or limit, or outside of a predetermined range of acceptable operating conditions. Similarly, MCD 112 can adjust the operation of a module 108 if the status information for that module 108 indicates the presence of an actual or potential fault (e.g., an alarm, or warning) or indicates the absence or removal of an actual or potential fault. Examples of a fault include, but are not limited to, an actual failure of a component, a potential failure of a component, a short circuit or other excessive current condition, an open circuit, an excessive voltage condition, a failure to receive a communication, the receipt of corrupted data, and the like. Depending on the type and severity of the fault, the faulty module's utilization can be decreased to avoid damaging the module, or the module's utilization can be ceased altogether. For example, if a fault occurs in a given module, then MCD 112 or LCD 114 can cause that module to enter a bypass state as described herein.
MCD 112 can control modules 108 within system 100 to achieve or converge towards a desired target. The target can be, for example, operation of all modules 108 at the same or similar levels with respect to each other, or within predetermined thresholds, limits, or conditions. This process is also referred to as balancing or seeking to achieve balance in the operation or operating characteristics of modules 108. The term “balance” as used herein does not require absolute equality between modules 108 or components thereof, but rather is used in a broad sense to convey that operation of system 100 can be used to actively reduce disparities in operation (or operative state) between modules 108 that would otherwise exist.
MCD 112 can communicate control information to LCD 114 for the purpose of controlling the modules 108 associated with the LCD 114. The control information can be, e.g., a modulation index and a reference signal as described herein, a modulated reference signal, or otherwise. Each LCD 114 can use (e.g., receive and process) the control information to generate switch signals that control operation of one or more components (e.g., a converter) within the associated module(s) 108. In some embodiments, MCD 112 generates the switch signals directly and outputs them to LCD 114, which relays the switch signals to the intended module component.
All or a portion of control system 102 can be combined with a system external control device 104 that controls one or more other aspects of the mobile or stationary application. When integrated in this shared or common control device (or subsystem), control of system 100 can be implemented in any desired fashion, such as one or more software applications executed by processing circuitry of the shared device, with hardware of the shared device, or a combination thereof. Non-exhaustive examples of external control devices 104 include: a vehicular ECU or MCU having control capability for one or more other vehicular functions (e.g., motor control, driver interface control, traction control, etc.); a grid or micro-grid controller having responsibility for one or more other power management functions (e.g., load interfacing, load power requirement forecasting, transmission and switching, interface with charge sources (e.g., diesel, solar, wind), charge source power forecasting, back up source monitoring, asset dispatch, etc.); and a data center control subsystem (e.g., environmental control, network control, backup control, etc.).
In
In the embodiments of
Examples of Modules within Cascaded Energy Systems
Module 108 can include one or more energy sources and a power electronics converter and, if desired, an energy buffer.
Converter 202 can also (or alternatively) be configured to perform AC to DC conversion (e.g., a rectifier) such as to charge a DC energy source from an AC source, DC to DC conversion, and/or AC to AC conversion (e.g., in combination with an AC-DC converter). In some embodiments, such as to perform AC-AC conversion, converter 202 can include a transformer, either alone or in combination with one or more power semiconductors (e.g., switches, diodes, thyristors, and the like). In other embodiments, such as those where weight and cost is a significant factor, converter 202 can be configured to perform the conversions with only power switches, power diodes, or other semiconductor devices and without a transformer.
Energy source 206 is preferably a robust energy storage device capable of outputting direct current and having an energy density suitable for energy storage applications for electrically powered devices. Energy source 206 can be an electrochemical battery, such as a single battery cell or multiple battery cells connected together in a battery module or array, or any combination thereof.
Energy source 206 can also be a high energy density (HED) capacitor, such as an ultracapacitor or supercapacitor. An HED capacitor can be configured as a double layer capacitor (electrostatic charge storage), pseudocapacitor (electrochemical charge storage), hybrid capacitor (electrostatic and electrochemical), or otherwise, as opposed to a solid dielectric type of a typical electrolytic capacitor. The HED capacitor can have an energy density of 10 to 100 times (or higher) that of an electrolytic capacitor, in addition to a higher capacity. For example, HED capacitors can have a specific energy greater than 1.0 watt hours per kilogram (Wh/kg), and a capacitance greater than 10-100 farads (F). As with the batteries described with respect to
Energy source 206 can also be a fuel cell. The fuel cell can be rechargeable, and can be a single fuel cell, multiple fuel cells connected in series or parallel, or a fuel cell module. The fuel cell can be configured to be rechargeable, Examples of fuel cell types include proton-exchange membrane fuel cells (PEMFC), phosphoric acid fuel cells (PAFC), solid acid fuel cells, alkaline fuel cells, high temperature fuel cells, solid oxide fuel cells, molten electrolyte fuel cells, and others. As with the batteries described with respect to
Energy buffer 204 can dampen or filter fluctuations in current across the DC line or link (e.g., +VDCL and −VDCL as described below), to assist in maintaining stability in the DC link voltage. These fluctuations can be relatively low (e.g., kilohertz) or high (e.g., megahertz) frequency fluctuations or harmonics caused by the switching of converter 202, or other transients. These fluctuations can be absorbed by buffer 204 instead of being passed to source 206 or to ports IO3 and IO4 of converter 202.
Power connection 110 is a connection for transferring energy or power to, from and through module 108. Module 108 can output energy from energy source 206 to power connection 110, where it can be transferred to other modules of the system or to a load. Module 108 can also receive energy from other modules 108 or a charging source (DC charger, single phase charger, multi-phase charger). Signals can also be passed through module 108 bypassing energy source 206. The routing of energy or power into and out of module 108 is performed by converter 202 under the control of LCD 114 (or another entity of system 102).
In the embodiment of
Module 108 can also include monitor circuitry 208 configured to monitor (e.g., collect, sense, measure, and/or determine) one or more aspects of module 108 and/or the components thereof, such as voltage, current, temperature or other operating parameters that constitute status information (or can be used to determine status information by, e.g., LCD 114). A main function of the status information is to describe the state of the one or more energy sources 206 of the module 108 to enable determinations as to how much to utilize the energy source in comparison to other sources in system 100, although status information describing the state of other components (e.g., voltage, temperature, and/or presence of a fault in buffer 204, temperature and/or presence of a fault in converter 202, presence of a fault elsewhere in module 108, etc.) can be used in the utilization determination as well. Monitor circuitry 208 can include one or more sensors, shunts, dividers, fault detectors, Coulomb counters, controllers or other hardware and/or software configured to monitor such aspects. Monitor circuitry 208 can be separate from the various components 202, 204, and 206, or can be integrated with each component 202, 204, and 206 (as shown in
LCD 114 can receive status information (or raw data) about the module components over communication paths 116, 118. LCD 114 can also transmit information to module components over paths 116, 118. Paths 116 and 118 can include diagnostics, measurement, protection, and control signal lines. The transmitted information can be control signals for one or more module components. The control signals can be switch signals for converter 202 and/or one or more signals that request the status information from module components. For example, LCD 114 can cause the status information to be transmitted over paths 116, 118 by requesting the status information directly, or by applying a stimulus (e.g., voltage) to cause the status information to be generated, in some cases in combination with switch signals that place converter 202 in a particular state.
The physical configuration or layout of module 108 can take various forms. In some embodiments, module 108 can include a common housing in which all module components, e.g., converter 202, buffer 204, and source 206, are housed, along with other optional components such as an integrated LCD 114. In other embodiments, the various components can be separated in discrete housings that are secured together.
Modules 108 of system 100 can be physically arranged with respect to each other in various configurations that depend on the needs of the application and the number of loads. For example, in a stationary application where system 100 provides power for a microgrid, modules 108 can be placed in one or more racks or other frameworks. Such configurations may be suitable for larger mobile applications as well, such as maritime vessels. Alternatively, modules 108 can be secured together and located within a common housing, referred to as a pack. A rack or a pack may have its own dedicated cooling system shared across all modules. Pack configurations are useful for smaller mobile applications such as electric cars. System 100 can be implemented with one or more racks (e.g., for parallel supply to a microgrid) or one or more packs (e.g., serving different motors of the vehicle), or combination thereof.
Examples of these and further configurations are described in Int'l. Appl. No. PCT/US20/25366, filed Mar. 27, 2020 and titled Module-Based Energy Systems Capable of Cascaded and Interconnected Configurations, and Methods Related Thereto, which is incorporated by reference herein in its entirety for all purposes.
Energy source 206 can be configured as any of the energy source types described herein (e.g., a battery as described with respect to
Ports IO3 and IO4 of energy buffer 204 can be connected to ports IO1 and IO2, respectively, of converter 202A, which can be configured as any of the power converter types described herein.
The switches can be any suitable switch type, such as power semiconductors like the metal-oxide-semiconductor field-effect transistors (MOSFETs) shown here, insulated gate bipolar transistors (IGBTs), or gallium nitride (GaN) transistors. Semiconductor switches can operate at relatively high switching frequencies, thereby permitting converter 202 to be operated in pulse-width modulated (PWM) mode if desired, and to respond to control commands within a relatively short interval of time. This can provide a high tolerance of output voltage regulation and fast dynamic behavior in transient modes.
In this embodiment, a DC line voltage VDCL can be applied to converter 202 between ports IO1 and IO2. By connecting VDCL to ports IO3 and IO4 by different combinations of switches S3, S4, S5, S6, converter 202 can generate three different voltage outputs at ports IO3 and IO4: +VDCL, 0, and −VDCL. A switch signal provided to each switch controls whether the switch is on (closed) or off (open). To obtain +VDCL, switches S3 and S6 are turned on while S4 and S5 are turned off, whereas −VDCL can be obtained by turning on switches S4 and S5 and turning off S3 and S6. The output voltage can be set to zero (including near zero) or a reference voltage by turning on S3 and S5 with S4 and S6 off, or by turning on S4 and S6 with S3 and S5 off. These voltages can be output from module 108 over power connection 110. Ports IO3 and IO4 of converter 202 can be connected to (or form) module IO ports 1 and 2 of power connection 110, so as to generate the output voltage for use with output voltages from other modules 108.
The control or switch signals for the embodiments of converter 202 described herein can be generated in different ways depending on the control technique utilized by system 100 to generate the output voltage of converter 202. In some embodiments, the control technique is a PWM technique such as space vector pulse-width modulation (SVPWM) or sinusoidal pulse-width modulation (SPWM), or variations thereof.
Each module 108 can be configured with multiple energy sources 206 (e.g., two, three, four, or more). Each energy source 206 of module 108 can be controllable (switchable) to supply power to connection 110 (or receive power from a charge source) independent of the other sources 206 of the module. For example, all sources 206 can output power to connection 110 (or be charged) at the same time, or only one (or a subset) of sources 206 can supply power (or be charged) at any one time. In some embodiments, the sources 206 of the module can exchange energy between them, e.g., one source 206 can charge another source 206. Each of the sources 206 can be configured as any energy source described herein (e.g., battery, HED capacitor, fuel cell). Each of the sources 206 can be the same class (e.g., each can be a battery, each can be an HED capacitor, or each can be a fuel cell), or a different class (e.g., a first source can be a battery and a second source can be an HED capacitor or fuel cell, or a first source can be an HED capacitor and a second source can be a fuel cell).
In this example embodiment of module 108B, primary energy source 202A, along with the other modules 108 of system 100, supplies the average power needed by the load. Secondary source 202B can serve the function of assisting energy source 202 by providing additional power at load power peaks, or absorbing excess power, or otherwise.
As mentioned both primary source 206A and secondary source 206B can be utilized simultaneously or at separate times depending on the switch state of converter 202B. If at the same time, an electrolytic and/or a film capacitor (CEs) can be placed in parallel with source 206B as depicted in
Converter 202C differs from that of 202B as switch portion 602B includes switches S1 and S2 configured as a half bridge and coupled between ports IO5 and IO2. A coupling inductor LC is connected between port IO1 and a node1 present between switches S1 and S2 such that switch portion 602B is configured to regulate voltage.
Control system 102 or LCD 114 can independently control each switch of converters 202B and 202C via control input lines 118-3 to each gate. In these embodiments and that of
The aforementioned zero voltage configuration for converter 202 (turning on S3 and S5 with S4 and S6 off, or turning on S4 and S6 with S3 and S5 off) can also be referred to as a bypass state for the given module. This bypass state can be entered if a fault is detected in the given module, or if a system fault is detected warranting shut-off of more than one (or all modules) in an array or system. A fault in the module can be detected by LCD 114 and the control switching signals for converter 202 can be set to engage the bypass state without intervention by MCD 112. Alternatively, fault information for a given module can be communicated by LCD 114 to MCD 112, and MCD 112 can then make a determination whether to engage the bypass state, and if so, can communicate instructions to engage the bypass state to the LCD 114 associated with the module having the fault, at which point LCD 114 can output switching signals to cause engagement of the bypass state.
In embodiments where a module 108 includes three or more energy sources 206, converters 202B and 202C can be scaled accordingly such that each additional energy source 206B is coupled to an additional IO port leading to an additional switch circuitry portion 602A or 602B, depending on the needs of the particular source. For example, a dual source converter 202 can include both switch portions 202A and 202B.
Modules 108 with multiple energy sources 206 are capable of performing additional functions such as energy sharing between sources 206, energy capture from within the application (e.g., regenerative braking), charging of the primary source by the secondary source even while the overall system is in a state of discharge, and active filtering of the module output. The active filtering function can also be performed by modules having a typical electrolytic capacitor instead of a secondary energy source. Examples of these functions are described in more detail in Int'l. Appl. No. PCT/US20/25366, filed Mar. 27, 2020, and titled Module-Based Energy Systems Capable of Cascaded and Interconnected Configurations, and Methods Related Thereto, and Int'l. Publ. No. WO 2019/183553, filed Mar. 22, 2019, and titled Systems and Methods for Power Management and Control, both of which are incorporated by reference herein in their entireties for all purposes.
Each module 108 can be configured to supply one or more auxiliary loads with its one or more energy sources 206. Auxiliary loads are loads that require lower voltages than the primary load 101. Examples of auxiliary loads can be, for example, an on-board electrical network of an electric vehicle, or an HVAC system of an electric vehicle. The load of system 100 can be, for example, one of the phases of the electric vehicle motor or electrical grid. This embodiment can allow a complete decoupling between the electrical characteristics (terminal voltage and current) of the energy source and those of the loads.
Module 108C can thus be configured to supply one or more first auxiliary loads in the manner described with respect to load 301, with the one or more first loads coupled to IO ports 3 and 4. Module 108C can also be configured to supply one or more second auxiliary loads in the manner described with respect to load 302. If multiple second auxiliary loads 302 are present, then for each additional load 302 module 108C can be scaled with additional dedicated module output ports (like 5 and 6), an additional dedicated switch portion 602, and an additional converter IO port coupled to the additional portion 602.
Energy source 206 can thus supply power for any number of auxiliary loads (e.g., 301 and 302), as well as the corresponding portion of system output power needed by primary load 101. Power flow from source-206 to the various loads can be adjusted as desired.
Module 108 can be configured as needed with two or more energy sources 206 (
Control system 102 can perform various functions with respect to the components of modules 108A, 108B, and 108C. These functions can include management of the utilization (amount of use) of each energy source 206, protection of energy buffer 204 from over-current, over-voltage and high temperature conditions, and control and protection of converter 202.
For example, to manage (e.g., adjust by increasing, decreasing, or maintaining) utilization of each energy source 206, LCD 114 can receive one or more monitored voltages, temperatures, and currents from each energy source 206 (or monitor circuitry). The monitored voltages can be at least one of, preferably all, voltages of each elementary component independent of the other components (e.g., each individual battery cell, HED capacitor, and/or fuel cell) of the source 206, or the voltages of groups of elementary components as a whole (e.g., voltage of the battery array, HED capacitor array, and/or fuel cell array). Similarly, the monitored temperatures and currents can be at least one of, preferably all, temperatures and currents of each elementary component independent of the other components of the source 206, or the temperatures and currents of groups of elementary components as a whole, or any combination thereof. The monitored signals can be status information, with which LCD 114 can perform one or more of the following: calculation or determination of a real capacity, actual State of Charge (SOC) and/or State of Health (SOH) of the elementary components or groups of elementary components; set or output a warning or alarm indication based on monitored and/or calculated status information; and/or transmission of the status information to MCD 112. LCD 114 can receive control information (e.g., a modulation index, synchronization signal) from MCD 112 and use this control information to generate switch signals for converter 202 that manage the utilization of the source 206.
To protect energy buffer 204, LCD 114 can receive one or more monitored voltages, temperatures, and currents from energy buffer 204 (or monitor circuitry). The monitored voltages can be at least one of, preferably all, voltages of each elementary component of buffer 204 (e.g., of CEB, CEB1, CEB2, LEB1, LEB2, DEB) independent of the other components, or the voltages of groups of elementary components or buffer 204 as a whole (e.g., between IO1 and IO2 or between IO3 and IO4). Similarly, the monitored temperatures and currents can be at least one of, preferably all, temperatures and currents of each elementary component of buffer 204 independent of the other components, or the temperatures and currents of groups of elementary components or of buffer 204 as a whole, or any combination thereof. The monitored signals can be status information, with which LCD 114 can perform one or more of the following: set or output a warning or alarm indication; communicate the status information to MCD 112; or control converter 202 to adjust (increase or decrease) the utilization of source 206 and module 108 as a whole for buffer protection.
To control and protect converter 202, LCD 114 can receive the control information from MCD 112 (e.g., a modulated reference signal, or a reference signal and a modulation index), which can be used with a PWM technique in LCD 114 to generate the control signals for each switch (e.g., S1 through S6). LCD 114 can receive a current feedback signal from a current sensor of converter 202, which can be used for overcurrent protection together with one or more fault status signals from driver circuits (not shown) of the converter switches, which can carry information about fault statuses (e.g., short circuit or open circuit failure modes) of all switches of converter 202. Based on this data, LCD 114 can make a decision on which combination of switching signals to be applied to manage utilization of module 108, and potentially bypass or disconnect converter 202 (and the entire module 108) from system 100.
If controlling a module 108C that supplies a second auxiliary load 302, LCD 114 can receive one or more monitored voltages (e.g., the voltage between IO ports 5 and 6) and one or more monitored currents (e.g., the current in coupling inductor LC, which is a current of load 302) in module 108C. Based on these signals, LCD 114 can adjust the switching cycles (e.g., by adjustment of modulation index or reference waveform) of S1 and S2 to control (and stabilize) the voltage for load 302.
Two or more modules 108 can be coupled together in a cascaded array that outputs a voltage signal formed by a superposition of the discrete voltages generated by each module 108 within the array.
System 100 can be arranged in a broad variety of different topologies to meet varying needs of the applications. System 100 can provide multi-phase power (e.g., two-phase, three-phase, four-phase, five-phase, six-phase, etc.) to a load by use of multiple arrays 700, where each array can generate an AC output signal having a different phase angle.
The concepts described with respect to the two-phase and three-phase embodiments of
System 100 can be configured such that arrays 700 are interconnected at electrical nodes between modules 108 within each array.
In the embodiments described herein, although it is advantageous for the number of modules 108 to be the same in each array 700 within system 100, such is not required and different arrays 700 can have differing numbers of modules 108. Further, each array 700 can have modules 108 that are all of the same configuration (e.g., all modules are 108A, all modules are 108B, all modules are 108C, or others) or different configurations (e.g., one or more modules are 108A, one or more are 108B, and one or more are 108C, or otherwise). As such, the scope of topologies of system 100 covered herein is broad.
As mentioned, control of system 100 can be performed according to various methodologies, such as hysteresis or PWM. Several examples of PWM include space vector modulation and sine pulse width modulation, where the switching signals for converter 202 are generated with a phase shifted carrier technique that continuously rotates utilization of each module 108 to equally distribute power among them.
An alternative is to utilize both a positive and a negative reference signal with the first (N−1)/2 carriers. A nine-level example is shown in
In multi-phase system embodiments, the same carriers can be used for each phase, or the set of carriers can be shifted as a whole for each phase. For example, in a three phase system with a single reference voltage (Vref), each array 700 can use the same number of carriers with the same relative offsets as shown in
The appropriate switching signals can be provided to each module by control system 102. For example, MCD 112 can provide Vref and the appropriate carrier signals to each LCD 114 depending upon the module or modules 108 that LCD 114 controls, and the LCD 114 can then generate the switching signals. Or all LCDs 114 in an array can be provided with all carrier signals and the LCD can select the appropriate carrier signals.
The relative utilizations of each module 108 can be adjusted based on status information to perform balancing or of one or more parameters as described herein. Balancing of parameters can involve adjusting utilization to minimize parameter divergence over time as compared to a system where individual module utilization adjustment is not performed. The utilization can be the relative amount of time a module 108 is discharging when system 100 is in a discharge state, or the relative amount of time a module 108 is charging when system 100 is in a charge state.
As described herein, modules 108 can be balanced with respect to other modules in an array 700, which can be referred to as intra array or intraphase balancing, and different arrays 700 can be balanced with respect to each other, which can be referred to as interarray or interphase balancing. Arrays 700 of different subsystems can also be balanced with respect to each other. Control system 102 can simultaneously perform any combination of intraphase balancing, interphase balancing, utilization of multiple energy sources within a module, active filtering, and auxiliary load supply.
The modulation indexes and Vrn can be used to generate the switching signals for each converter 202. The modulation index can be a number between zero and one (inclusive of zero and one). For a particular module 108, the normalized reference Vrn can be modulated or scaled by Mi, and this modulated reference signal (Vrnm) can be used as Vref (or −Vref) according to the PWM technique described with respect to
Controller 906 can generate an Mi for each module 108 using any type or combination of types of status information (e.g., SOC, temperature (T), Q, SOH, voltage, current) described herein. For example, when using SOC and T, a module 108 can have a relatively high Mi if SOC is relatively high and temperature is relatively low as compared to other modules 108 in array 700. If either SOC is relatively low or T is relatively high, then that module 108 can have a relatively low Mi, resulting in less utilization than other modules 108 in array 700. Controller 906 can determine Mi such that the sum of module voltages does not exceed Vpk. For example, Vpk can be the sum of the products of the voltage of each module's source 206 and Mi for that module (e.g., Vpk=M1V1+M2V2+M3V3 . . . +MNVN, etc). A different combination of modulation indexes, and thus respective voltage contributions by the modules, may be used but the total generated voltage should remain the same.
Controller 900 can control operation, to the extent it does not prevent achieving the power output requirements of the system at any one time (e.g., such as during maximum acceleration of an EV), such that SOC of the energy source(s) in each module 108 remains balanced or converges to a balanced condition if they are unbalanced, and/or such that temperature of the energy source(s) or other component (e.g., energy buffer) in each module remains balanced or converges to a balanced condition if they are unbalanced. Power flow in and out of the modules can be regulated such that a capacity difference between sources does not cause an SOC deviation. Balancing of SOC and temperature can indirectly cause some balancing of SOH. Voltage and current can be directly balanced if desired, but in many embodiments the main goal of the system is to balance SOC and temperature, and balancing of SOC can lead to balance of voltage and current in a highly symmetric system where modules are of similar capacity and impedance.
Since balancing all parameters may not be possible at the same time (e.g., balancing of one parameter may further unbalance another parameter), a combination of balancing any two or more parameters (SOC, T, Q, SOH, V, I) may be applied with priority given to either one depending on the requirements of the application. Priority in balancing can be given to SOC over other parameters (T, Q, SOH, V; I), with exceptions made if one of the other parameters (T, Q, SOH, V, I) reaches a severe unbalanced condition outside a threshold.
Balancing between arrays 700 of different phases (or arrays of the same phase, e.g., if parallel arrays are used) can be performed concurrently with intraphase balancing.
Controllers 900 and 950 (as well as balance controllers 906 and 910) can be implemented in hardware, software or a combination thereof within control system 102. Controllers 900 and 950 can be implemented within MCD 112, distributed partially or fully among LCDs 114, or may be implemented as discrete controllers independent of MCD 112 and LCDs 114.
Modules 108 can be connected between the modules of different arrays 700 for the purposes of exchanging energy between the arrays, acting as a source for an auxiliary load, or both. Such modules are referred to herein as interconnection (IC) modules 1081C. IC module 108IC can be implemented in any of the already described module configurations (108A, 108B, 108C) and others to be described herein. IC modules 1081C can include any number of one or more energy sources, an optional energy buffer, switch circuitry for supplying energy to one or more arrays and/or for supplying power to one or more auxiliary loads, control circuitry (e.g., a local control device), and monitor circuitry for collecting status information about the IC module itself or its various loads (e.g., SOC of an energy source, temperature of an energy source or energy buffer, capacity of an energy source, SOH of an energy source, voltage and/or current measurements pertaining to the IC module, voltage and/or current measurements pertaining to the auxiliary load(s), etc.).
Switch circuitry units 604 are coupled between positive and negative terminals of energy source 206 and have an output that is connected to an IO port of module 108IC. Units 604-PA through 604-PΩ can be controlled by control system 102 to selectively couple voltage +VIC or −VIC to the respective module I/O ports 1 through Ω. Control system 102 can control switch circuitry 603 according to any desired control technique, including the PWM and hysteresis techniques mentioned herein. Here, control circuitry 102 is implemented as LCD 114 and MCD 112 (not shown). LCD 114 can receive monitoring data or status information from monitor circuitry of module 108IC. This monitoring data and/or other status information derived from this monitoring data can be output to MCD 112 for use in system control as described herein. LCD 114 can also receive timing information (not shown) for purposes of synchronization of modules 108 of the system 100 and one or more carrier signals (not shown), such as the sawtooth signals used in PWM (
For interphase balancing, proportionally more energy from source 206 can be supplied to any one or more of arrays 700-PA through 700-PΩ that is relatively low on charge as compared to other arrays 700. Supply of this supplemental energy to a particular array 700 allows the energy output of those cascaded modules 108-1 thru 108-N in that array 700 to be reduced relative to the unsupplied phase array(s).
For example, in some example embodiments applying PWM, LCD 114 can be configured to receive the normalized voltage reference signal (Vrn) (from MCD 112) for each of the one or more arrays 700 that module 108IC is coupled to, e.g., VrnPA through VrnPΩ. LCD 114 can also receive modulation indexes MiPA through MiPΩ for the switch units 604-PA through 604-PΩ for each array 700, respectively, from MCD 112. LCD 114 can modulate (e.g., multiply) each respective Vrn with the modulation index for the switch section coupled directly to that array (e.g., VrnA multiplied by MiA) and then utilize a carrier signal to generate the control signal(s) for each switch unit 604. In other embodiments, MCD 112 can perform the modulation and output modulated voltage reference waveforms for each unit 604 directly to LCD 114 of module 108IC. In still other embodiments, all processing and modulation can occur by a single control entity that can output the control signals directly to each unit 604.
This switching can be modulated such that power from energy source 206 is supplied to the array(s) 700 at appropriate intervals and durations. Such methodology can be implemented in various ways.
Based on the collected status information for system 100, such as the present capacity (Q) and SOC of each energy source in each array, MCD 112 can determine an aggregate charge for each array 700 (e.g., aggregate charge for an array can be determined as the sum of capacity times SOC for each module of that array). MCD 112 can determine whether a balanced or unbalanced condition exists (e.g., through the use of relative difference thresholds and other metrics described herein) and generate modulation indexes MiPA through MiPΩ accordingly for each switch unit 604-PA through 604-PΩ.
During balanced operation, Mi for each switch unit 604 can be set at a value that causes the same or similar amount of net energy over time to be supplied by energy source 206 and/or energy buffer 204 to each array 700. For example, Mi for each switch unit 604 could be the same or similar, and can be set at a level or value that causes the module 108IC to perform a net or time average discharge of energy to the one or more arrays 700-PA through 700-PΩ during balanced operation, so as to drain module 1081C at the same rate as other modules 108 in system 100. In some embodiments, Mi for each unit 604 can be set at a level or value that does not cause a net or time average discharge of energy during balanced operation (causes a net energy discharge of zero). This can be useful if module 108IC has a lower aggregate charge than other modules in the system.
When an unbalanced condition occurs between arrays 700, then the modulation indexes of system 100 can be adjusted to cause convergence towards a balanced condition or to minimize further divergence. For example, control system 102 can cause module 108IC to discharge more to the array 700 with low charge than the others, and can also cause modules 108-1 through 108-N of that low array 700 to discharge relatively less (e.g., on a time average basis). The relative net energy contributed by module 1081C increases as compared to the modules 108-1 through 108-N of the array 700 being assisted, and also as compared to the amount of net energy module 1081C contributes to the other arrays. This can be accomplished by increasing Mi for the switch unit 604 supplying that low array 700, and by decreasing the modulation indexes of modules 108-1 through 108-N of the low array 700 in a manner that maintains Vout for that low array at the appropriate or required levels, and maintaining the modulation indexes for other switch units 604 supplying the other higher arrays relatively unchanged (or decreasing them).
The configuration of module 108IC in
Furthermore, IC modules can be configured to exchange energy between two or more subsystems of system 100.
In this embodiment, each module 108IC is coupled with a first array of subsystem 1000-1 (via IO port 1) and a first array of subsystem 1000-2 (via IO port 2), and each module 1081C can be electrically connected with each other module 1081C by way of I/O ports 3 and 4, which are coupled with the energy source 206 of each module 1081C as described with respect to module 108C of
Each module 1081C has a switch unit 604-1 coupled with IO port 1 and a switch unit 604-2 coupled with I/O port 2, as described with respect to
In systems with IC modules between phases, interphase balancing can also be performed by neutral point shifting (or common mode injection) as described above. Such a combination allows for more robust and flexible balancing under a wider range of operating conditions. System 100 can determine the appropriate circumstances under which to perform interphase balancing with neutral point shifting alone, interphase energy injection alone, or a combination of both simultaneously.
IC modules can also be configured to supply power to one or more auxiliary loads 301 (at the same voltage as source 206) and/or one or more auxiliary loads 302 (at voltages stepped down from source 302).
The energy source 206 of each IC module can be at the same voltage and capacity as the sources 206 of the other modules 108-1 through 108-N of the system, although such is not required. For example, a relatively higher capacity can be desirable in an embodiment where one module 1081C applies energy to multiple arrays 700 (
Energy sources 206 described herein can be used in systems 100 described herein in both first life and second life applications. A first life of a source 206 is an original application in which source 206 is used. For example, the first life application is the first implementation in which sources 206 are put to use by the first customer of sources 206 after their original manufacture (and not refurbishment). The user of sources 206 in their first life will typically have received sources 206 from the manufacturer, distributor, or original equipment manufacturer (OEM). Batteries 206 used in a first life application will typically have the same electrochemistry (e.g., will have the same variant of lithium ion electrochemistry (e.g., LFP, NMC)) and will have the same nominal voltage and will have a capacity variation across the pack or system that is minimal (e.g., 5% or less). Use of an energy storage system with batteries 206 in their first life application will result in batteries 206 having a longer lifespan in that first life application, and upon removal from that first life application, the batteries 206 will be more similar in terms of capacity degradation than batteries from a first life application not using the energy storage system.
As used herein, a “second life” application refers to any application or implementation after the first life application (e.g., a second implementation, third implementation, fourth implementation, etc.) of source 206. A second life energy source refers to any energy source (e.g., battery or HED capacitor) implemented in that source's second life application.
An example of a first life application for batteries 206 is within an energy storage system for an EV. Then, at the end of that life (e.g., after 100,000 miles of driving, or after degradation of the batteries within that battery pack by a threshold amount), the batteries 206 can be removed from the battery pack, optionally subjected to refurbishing and testing, and then implemented in a second life application that can be, e.g., used within a stationary energy storage system (e.g., residential, commercial, or industrial energy buffering, EV charging station energy buffering, renewable source (e.g., wind, solar, hydroelectric), energy buffering, and the like) or another mobile energy storage system (e.g., battery pack for an electric car, bus, train, or truck). Similarly, the first life application can be a first stationary application and the second life application can be a stationary or mobile application.
For the second life application, sources 206 can be selected and/or utilized by system 100 to minimize (or at least reduce) any differences in initial capacity and nominal voltage. For example, sources 206 having a capacity difference of 5% or more can be included within system 100 and operated to provide energy for a load. In another example, an operator or automated system can select sources 206 for system 100 that have a capacity difference within a threshold amount, e.g., to reduce the initial capacity differences between sources of system 206. If modules 108 are compatible with both the first and second life application (e.g., with or without reconfiguration), modules 108 can be selected for the second life application based on the capacity difference of sources 206 of modules 108.
System 100 can adjust utilization of each source 206 individually such that sources 206 within system 100 or packs of system 100 are relatively balanced in terms of SOC or total charge (SOC times capacity) as the pack or system 100 is discharged, even though the sources 206 in system 100 can have widely varying capacities. Similarly, system 100 can maintain balance as the pack or system 100 is charged. Sources 206 can vary not only in terms of capacity but also in nominal voltage, power rating, electrochemical type (e.g., a combination of LFP and NMC batteries) and the like. Thus, system 100 can be used such that all modules 206 within system 100 or each pack of system 100 are second life energy sources (or such that a combination of first life and second life energy sources are used), having various combinations of different characteristics.
In one example, system 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having energy capacity variations of 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more, 30% or more, 5-30%, 10-30%, and/or 20-30%.
In another example, system 100 can include second energy life sources 206 (and optionally one or more first life energy sources 206) having energy capacity per mass density variations of 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more, 30% or more, 5-30%, 10-30%, and/or 20-30%.
In another example, system 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having peak power per mass density variations of 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more, 30% or more, 5-30%, 10-30%, and/or 20-30%.
In another example, system 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having nominal voltage variations of 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more, 30% or more, 5-30%, 10-30%, and/or 20-30%.
In another example, system 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having operating voltage range variations of 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more, 30% or more, 5-30%, 10-30%, and/or 20-30%.
In another example, system 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having maximum specified current rise time variations of 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more, 30% or more, 5-30%, 10-30%, and/or 20-30%.
In another example, system 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having specified peak current variations of 2% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more, 30% or more, 5-30%, 10-30%, and/or 20-30%.
A variation of X % (e.g., 5% or more, or 5 to 30%) can be met by a variation between the module 108 having the highest value for that parameter and the module 108 having the lowest value for that parameter within system 100. For example, a variation of 5% or more in capacity can be met by a system 100 where the module 108 with the lowest capacity source 206 has a capacity that is 95% or less than that of the module 108 with the highest capacity source 206. For each and every embodiment and parameter disclosed herein, the time at which the system 100 having one or more second life sources satisfies the X % variation condition in that parameter can be at installation of the system 100, at commissioning of the system 100, after replacement of one source 206 with another source 206, after operation of system 100 for 10 hours or more, after operation of system 100 for 100 hours or more, after operation of system 100 for 1000 hours or more, and/or after operation of system 100 for 10,000 hours or more. For example, a variation of capacity of 5% or more can occur after system 100 is operated for 1000 hours, even though the variation in capacity was not present at the time of commissioning. This reflects the capability of the embodiments of system 100 to continue to operate with and account for capacity differences between sources 206 that grow over time of operation.
In another example, system 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having variations of electrochemical type (e.g., lithium ion batteries with non-lithium ion batteries, or different lithium ion batteries (e.g., any combination of NMC, LFP, LTO, or other lithium ion battery-types).
System 100 can include second life energy sources 206 (and optionally one or more first life energy sources 206) having any combination of the characteristics provides in the preceding examples.
Example embodiments will now be described herein relating to fast charging techniques for energy sources using pulse heating and/or pulse charging techniques. The embodiments will be described primarily in the context of energy sources 206 that are batteries, although the embodiments are applicable to other energy source types as well (e.g., high energy density capacitors and fuel cells). The embodiments can be applied to charge a battery having a single cell, a battery having multiple cells (e.g., connected in series, parallel, or a combination thereof, sometimes referred to as a battery module), and systems (e.g., a battery pack) having multiple battery modules (e.g., connected in series, parallel, or a combination thereof.
Examples of battery types suitable for use with the present subject matter include solid state batteries, liquid electrotype based batteries, liquid phase batteries as well as flow batteries such as lithium (Li) metal batteries, Li ion batteries, Li air batteries, sodium ion batteries, potassium ion batteries, magnesium ion batteries, alkaline batteries, nickel metal hydride batteries, nickel sulfate batteries, lead acid batteries, zinc-air batteries, and others. Some examples of Li ion battery types include Li cobalt oxide (LCO), Li manganese oxide (LMO), Li nickel manganese cobalt oxide (NMC), Li iron phosphate (LFP), Li nickel cobalt aluminum oxide (NCA), and Li titanate (LTO).
While not required to be used with any particular configuration of energy storage system, the embodiments of system 100 described herein can particularly benefit from use with the present fast charging embodiments; When used with the embodiments of system 100 to charge energy sources 206 therein, converter 202 of each module 108 is independently controlled to apply a positive, zero, or negative pulse from power connection 110 to source 206. The AC or DC signal applied to power connection 110 can be fed back into the sources 206 in the reverse fashion to the process described herein for generating a superposition of all output pulses from all modules 108. Each converter 202 can be switched at frequencies greater than 100 Hz to apply pulses, e.g., of five milliseconds (ms) or less at 50% duty cycle. Longer or shorter pulse durations with different duty cycles can also be used. This pulsing capability allows the energy source to be charged and/or heated as will be described herein.
Converters 202 can be controlled using a control system applying a pulse width modulation technique, a hysteresis technique, or another technique that strives to utilize all modules equally over time. Each module 108 can monitor the status of the energy source(s) 206 of that module 108 (e.g., state of charge (SOC), temperature, voltage, current, etc.) and feedback this monitored information to control system 102, which can adjust charge utilization of each module 108 individually to maintain balance, or converge towards a balanced condition, of the chosen parameter or parameters to be balanced (e.g., SOC and/or temperature).
The cascaded topology of system 100 permits the charge voltage or charge current from the charge source to be divided amongst the energy sources as needed to implement charging schemes of varying complexity. For example, voltage (or current) can be applied in a pulsed manner where some sources 206 are charged at certain times and others are not, generally provided that the total voltage applied to sources 206 (and other charge sinks of the system) is equal to the DC or AC voltage supplied to system 100 by the charge source at that moment in time. The voltage and duration of the pulse applied (as well as the duration of the rest time between pulses) can be varied and timed based on the state of those sources 206 as monitored by each module 108 (e.g., monitor circuitry 208 and LCD 114). Thus the division of voltages between modules 108 allows both charging and resting of the sources 206 of the modules 108 as needed.
The embodiments can be used to charge sources 206 with varying degrees of granularity. For example, a battery module can be pulsed as a whole, e.g., one pulse can be applied for all of the cells making up that battery module. Alternatively, additional switching circuitry (e.g., in addition to the configurations shown for converter 202) can be included for each individual cell such that each cell of the battery module can be pulsed independently. For example, a system 100 having N battery modules each having M cells can be configured with NM (N multiplied by M) converters or switch circuits. Other levels of granularity are possible, such as the capability to pulse charge groups of cells within each battery module (e.g., the cells are divided into two groups each of which can be charged independently such that the system has 2N converters or switch circuits). Control of the switch circuitry for the various battery modules and/or cells can be performed by control system 102 communicatively coupled with system modules 108 (e.g., MCD 112 communicatively coupled with LCDs 114).
Provided herein are example embodiments related to pulse charging of energy sources at improved speeds to accomplish fast or rapid charging. The example embodiments pertain to the application of voltage or current pulses to a battery in order to raise the temperature of that battery through localized heating, the application of voltage or current pulses to the battery in order to charge the battery, the application of constant (non-pulsed) voltage or constant current to the battery in order to charge the battery at higher temperatures, the monitoring of the battery for degradatory conditions while charging, and any combination thereof. The embodiments described herein can enable stationary and mobile energy storage systems to be charged at a wide range of C rates provided certain voltage and temperature constraints are not exceeded for the battery cells. For example, the embodiments can allow an EV with 100 kilowatt hour (kWh) storage capacity to be charged from zero to 80% of capacity in 10 minutes (or less) without substantially degrading the capacity over the rated lifetime of the battery pack.
To provide more granular control, protocols 1100 can also be applied within a cascaded modular energy storage system 100 such as that described herein, where each module 108 includes a battery 206 that may be only a single cell or that may include two or more cells (e.g., between 2 and 100 cells), and the number of modules 108 can be two or greater (e.g., between 2 and 1000 modules 108). Converter 202 of each module 108 can be independently controlled as described herein such that protocols 1100 can be independently performed by each module 108 of system 100. For example, considering a battery pack having 12 modules 108, each having a battery 206 that includes 12 cells, protocols 1100 can be applied independently by each module 108 to charge each battery 206 having 12 cells in 15 minutes or less, and thus charge the entire battery pack in the same or similar time. Because the conditions of batteries 206 within system 100 will vary, and because the embodiments can adjust the charge rate based on feedback from each battery 206, the charge time for each battery 206 may vary. Some batteries 206 may be at 2-3% SOC while others are at or near 0% SOC or some percentage therebetween at the start of a charge cycle. Some batteries 206 may have higher capacities than others and will require longer times to reach the desired SOC. Some batteries 206 may, while charging, exhibit signs of degradation or other characteristics necessitating that the charge process be slowed.
In order to enable discussion of protocol 1100 in greater detail,
Applying a high current pulse to a battery cell can cause the cell to exhibit an overvoltage distributed between the cathode, anode, and the cell itself.
The voltage drop over the anode is an accumulation of the voltage (η*ohmic) due to ohmic resistance and the voltage (η*act) due to the electrochemical interface when the cell is not equilibrated, and the voltage (η*Nernst) attributed to the open circuit voltage change from diffusion when the cell is not equilibrated.
Referring back to
Preheating phase 1110 involves application of a preheating pulse signal 1112 as a train or sequence of pulses, where each pulse alternates from a charge pulse (negative current) to a discharge pulse (positive current) of equal or substantially equal duration, optionally with a time gap between application of the charge and discharge pulse pair.
Preheating phase 1110 can achieve local heating by raising the temperature of anode current collector 1205, cathode current collector 1207 and electrolyte 1209 (
f
AL
,f
CL
>f
preheat
>f
A Main
,f
A Side
,f
C Main
,f
C Side, (1)
where fAL is the characteristic frequency where the inductance on the anode begins to significantly impact current flow for the particular application given by (2), fCL is the characteristic frequency where the inductance on the cathode begins to significantly impact current flow for the particular application given by (3), fA Main is the characteristic frequency of the main reaction which is the intercalation reaction of lithium ions on the anode given by (4), fA Side is the characteristic frequency of side reactions on the anode given by (5), fC Main is the characteristic frequency of the main reaction which is the intercalation reaction of lithium ions on the cathode given by (6), and fC Side is the characteristic frequency of side reactions on the cathode given by (7).
f
AL<(Rohmic A)/2πLA (2)
f
CL<(Rohmic C)/2πLC (3)
f
A Main>1/[2π(RCT Main+RWarburg Main)CDL] (4)
f
A Side>1/[2π(RCT Side+RWarburg Side)CDL] (5)
f
C Main>1/[2π(RCT Main+RWarburg Main)CDL] (6)
f
C Side>1/[2π(RCT Side+RWarburg Side)CDL] (7)
In each of (1)-(7), frequencies selected to be further from the constraint can provide increased benefit. For example, selection of fpreheat to be substantially lower than fAL, fCL will permit the inductive voltage component to be suppressed to avoid voltage spikes.
Preheating signal 1112 may be at a single frequency, with each pulse having a rectangular or substantially rectangular form (as visualized in time domain). In other embodiments, preheating signals 1112 can be implemented in a more complex fashion having multiple frequency components, such as a primary pulse train and secondary pulses, in the frequency domain between one hertz (Hz) up to one megahertz (Mhz). The frequency of preheating signal 1112 is chosen such that it causes the voltage drop to occur primarily through the electrolyte impedance and the current collector impedance, and not through the charge transfer impedance. In various embodiments preheating signal 1112 has a frequency range between 100 Hz and 100 kilohertz (kHz).
Preheating phase 1110 causes a temperature increase at local regions within the battery cells by generating heat by way of the ohmic impedances to heat the active material while bypassing activation of electrochemical reactions such as side reactions (e.g., decomposition of the electrolyte, decomposition of the active, lithium plating) or main electrochemical reactions (e.g., lithiation). These reactions are preferably bypassed such that they do not substantially occur (within reasonable tolerances identified by those of ordinary skill in the art permitting prolonged functional operation in the respective commercial, research, or industrial application). Phase 1110 can be performed to warm the cell until the activation impedance and total impedance is small enough such that the overvoltage on the anode drives the electrochemical reaction and not lithium plating. Phase 1110 therefore permits rapid heating of the electrochemical interface and bulk material temperature control to permit subsequent charging without causing damage due to side reactions or material stress due to rapid degradation (e.g., lithiation or delithiation) of the anode and cathode material.
Preheating phase 1110 can be applied until all cells of source 206 reach a minimum temperature threshold, provided that no one cell exceeds a maximum temperature threshold. If a cell reaches the maximum threshold, then preheating phase 1110 can be slowed, or stopped, or protocol 1100 can transition to the next phase (first or second charging phases 1120, 1130) as described herein. Cell temperatures can be measured directly with a temperature sensor (e.g., infrared) or indirectly (e.g., temperature in a subgroup of cells or in proximity with cells). As an alternative, or in combination with direct sensing, temperature for one or more cells, including all cells, can be measured with one sensor (e.g., an infrared image of multiple cells). Temperature can also be inferred by use of a model or look up table with reference to other indirect metrics (e.g., voltage, current, impedance), optionally based on data collected from previously characterized cells. Temperature thresholds for this and other phases are preferably correlated to the internal temperature of the cell where the electrolyte and active material are located. Thus, if a battery cell surface temperature is measured (e.g., with a thermistor or optical device) then the threshold is set for the surface temperature that correlates to the desired internal cell temperature based on an estimation, lookup table, or model.
Preheating phase 1110 raises the temperature of battery 206 to a first temperature threshold, which in the example of
The C rate of the pulses applied during preheating phase 1110 can vary widely, and is primarily dependent on the ohmic characteristics, applied voltages, and thermal behavior of the cells during this phase. C rates up to 30 C and higher can be applied in phase 1110. Furthermore, while phase 1110 can be applied such that no net charging or discharging occurs, in other embodiments the length of the charge pulse can be slightly longer (e.g., 1-15%) than the length of the discharge pulse to begin charging the cells at a relatively low rate as compared to the subsequent phases. This can occur, for example, towards the transition from preheating phase 1110 to first charge phase 1120 as battery 206 is heating towards the transition threshold temperature or time. Thus phase 1110 can be divided into a first subphase 1114 where no charging occurs, and a second subsequent subphase 1116 after reaching a higher temperature where the charge pulse length is made longer than the discharge pulse length to commence charging but at a slower rate than the pulse charging second phase described below. An example embodiment of preheating signal 1112 applied during both subphases 1114 and 1116 is depicted in
The transition of phase 1110 to first charge phase 1120, or alternatively the transition of first subphase 1114 to second subphase 1116, can occur at a condition where pulse charging can occur at a high C rate for faster charging without causing a significant side reaction, such as lithium plating. In some embodiments, this condition can be such that the average current of the intended pulse charging rate times the Warburg impedance (RWarburg) does not result in a voltage that exceeds the overvoltage range for either electrode. In other embodiments, this condition that can govern transition to pulse charging can be when RWarburg is reduced to 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the total impedance for each electrode. For embodiments where preheating phase 1110 transitions directly to a constant current charging phase 1130 (without pulse charging phase 1120), the transition condition can, in some examples, be when the activation impedance drops to 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the total impedance for each electrode.
In some embodiments, preheating signal 1112 is applied while monitoring a temperature of the subject source 206 and monitoring a temperature of the exterior ambient environment around the subject source 206, e.g., the environment to which subject source 206 loses heat. The difference between the source temperature and that of the ambient environment can be monitored and compared to a threshold absolute difference (e.g., 20 or 30 degrees Celsius) or alternatively a gradient (e.g., a threshold rate at which the source temperature increases past the ambient temperature). This is to ensure that the temperature disparity between source and the ambient does not become so severe that the source undergoes thermally induced mechanical stresses to the level sufficient to cause damage. The preheating signal amplitude can be decreased, or the gap time between adjacent charge-discharge pulse pairs can be increased, or a wait period can be introduced where no signal is applied, if the threshold is neared, reached, or exceeded depending on the particular implementation. In some embodiments, preheat phase 1110 can be performed while all external cooling apparatuses (e.g., fans, liquid coolant circulation) are not simultaneously operated so as to minimize the temperature difference between ambient and source 206.
First charge phase 1120 is a pulse charging phase where a pulse charge signal is applied to battery 206. Phase 1120 allows faster charging at high C rates with a reduced activation overvoltage and with the occurrence of reduced side reactions as explained in greater detail herein.
The pulses applied in phase 1110 can have a voltage that exceeds the cutoff voltages (upper and lower) of energy-source 206. In-some embodiments, the amount that the phase 1110 pulses can exceed the cutoff voltage is limited by the breakdown voltage of the electrolyte. The pulses applied in phase 1120 can also have a voltage that exceeds the recommended cutoff voltages (upper and lower) of energy source 206. In some embodiments, the amount that the phase 1120 pulses can exceed the cutoff voltage is equal to or less than the pulse charge current times the remaining impedance for the electrode (that portion of the impedance not avoided by pulse charging, which is the ohmic impedance plus any remaining activation impedance).
Optimal frequency and duration 1124 of the applied pulse is dependent on the battery type. In many embodiments, a frequency (Fpulse) of pulse charge signal 1122 complies with equation (8):
f
pulse>1/(RCT·CDL). (8)
fpulse values above twice that of equation (8) substantially eliminate activation impedance and activation overvoltage (e.g., eliminate the RCT and η*act components of
Pulse charging can allow the charge current to be substantially increased because voltage drops over non-ohmic impedances are eliminated or minimized. In some embodiments, the non-ohmic Warburg impedance (RWarburg) and non-ohmic activation impedance (RCT) are periodically measured and fpulse is chosen such that the sum of the Warburg impedance and activation impedances exceeds a threshold proportion of the total impedance. For example, in pulse charging with twice the applied current as in constant current charging, and with a duty cycle of 50%, the sum of the non-ohmic impedances that are avoided is preferably over 50% of the total impedance. Stated differently the ohmic impedance is preferably less than 50% of the total impedance. The total impedance can be measured or can be based on a pre-programmed estimate corresponding to varying states of charge. The threshold proportion can be 50% of the total impedance, 60% of the total impedance, 70% of the total impedance, or others. Alternatively, fpulse can be chosen such that the Warburg impedance is above a proportion (e.g., 60%, 50%, 40%, or 30%) of the total impedance, and/or fpulse can be chosen such that the activation impedance is above a proportion (e.g., 60%, 50%, 40%, or 30%) of the total impedance.
Depending on the duty cycle the time average C rate can be larger or smaller to meet the desired target (e.g., 80% SOC within approximately nine minutes). The magnitude of the C rate itself is not a constraint insomuch as the applied C rate does not exceed the voltage and temperature constraints described herein, nor the chemical and physical constraints of the battery cell, and the electrical and physical constraints of the system being charged and the charger. Thus, time average C rates for the second phase can vary significantly across embodiments. In one example, the time average C rate for the pulse charging phase 1120 is from 4 C-8 C, although the present subject matter is not limited to such. For protocol 1100, time average C rates of 30 C and higher are within the scope of the present subject matter.
Pulse signal 1122 can be applied at a current magnitude such that each battery cell exhibits a voltage response that is greater than the open circuit voltage of the cell but less than an upper cut off voltage of the electrochemical interface voltage on the anode and on the cathode electrodes (excluding ohmic over voltages). In various embodiments, the pulses are applied such that each cell does not exceed the overvoltage range of the anode alone, the overvoltage range of the cathode alone, or the overvoltage range of the anode and cathode together. Pulse charging can drive the cell voltage to a higher voltage than constant current charging in the same (lower) temperature range as a result of the reduced activation overvoltage.
The optimal duration of phase 1120 is dependent on the battery type, and longer pulse charging phases can be used for chemistries that have more activation or activation that persists at higher temperatures. Pulse charging phase 1120 can continue until the activation impedance is reduced to 50% or less of the total initial impedance (e.g., as of the commencement of phase 1120). In other embodiments, phase 1120 can continue until the activation impedance is reduced to 40% or below, 30% or below, 20% or below, or 10% or below of the total impedance. Other constraints can also be determinative of when phase 1120 ends, such as cell temperature and cutoff voltage.
Referring back to
In the embodiment of
Second charging phase 1130 is a constant current charging phase where a constant current signal is applied to battery 206 without pulsing. Phase 1130 is intended for relatively higher temperatures at the electrochemical interface where that activation and diffusion-based impedances are reduced (e.g., the RCT, and RWarburg components of
The constant current can be applied at a relatively high time average C rate such as 4C-8C (or higher). With constant current, there will generally be no difference between time average C rate and the actual C rate when current is applied, but in some cases minor variation in current may make time average C rate the more relevant metric.
In some embodiments, during second charge phase 1130, the magnitude of the constant current charge signal can be varied as the charge process proceeds. For example, in some embodiments the magnitude of constant current charge signal 1132 can begin phase 1130 at a relatively high C rate, then progressively transition to lower C rate values as the charge process proceeds in order to avoid exceeding the overvoltage range as the SOC increases (see
Protocol 1100 is not required to execute all three phases 1110, 1120, and 1130. In some embodiments, first charge phase 1120 can be omitted and protocol 1100 can proceed immediately from pulse preheating phase 1110 to constant current charging phase 1130. In other embodiments, second charge phase 1130 can be omitted and protocol 1100 can proceed immediately from pulse preheating phase 1110 to first charge phase 1120 and subsequently end. In still other embodiments, pulse preheating phase 1110 can be omitted, for example, in cases where battery 206 is already sufficiently heated. Example embodiments with these and other variations to protocol 1100 are described with respect to
Protocol 1100 also include monitoring each battery 206 for indications of potentially degradatory conditions. This monitoring, which can be performed during any and all of phases 1110, 1120, and 1130, can include voltage and/or impedance response analysis and/or monitoring for an indication that lithium plating has occurred. For example, the voltage and impedance of each battery 206 can be monitored with voltage and impedance response analysis to detect an indication of accelerated or decelerated side reactions (e.g., see
A voltage response of battery 206 to signal 1402 can be monitored as shown in the middle plot 1410. A normal voltage response 1412 is shown at left for the example where no lithium plating has occurred, and a voltage response 1414 indicating that lithium plating has occurred is shown at right, specifically an indication that plated lithium has been stripped. If a lithium plating event has occurred then this becomes evident in the portion of voltage response 1414 to the discharge pulse 1406, typically a relatively rapid transition in the response 1414 from one voltage to another voltage while the discharge pulse is being applied at a generally constant magnitude. This rapid transition in voltage response 1414 is indicative of plated lithium being subsequently stripped. Thus the response is generated by stripping of lithium, and is thus indicative of lithium plating having occurred previous to the application of discharge pulse 1407.
The plating can be detected directly from the voltage response, or from a derivation 1422 of the voltage response as depicted in plot 1420 at bottom. The derivation of the voltage response produces a transition (e.g., a peak or spike, either positive or negative) at times where the voltage response undergoes a relatively significant nonlinear transition, such as where the current pulses are initiated and terminated 1424, and also where a lithium stripping event occurs as shown by 1426. In some embodiments, only the voltage response or derivation thereto with respect to the discharge pulse is monitored. If lithium plating is detected then a characteristic of the charging signal can be modified as described with respect to impedance monitoring above. Lithium plating detection 1400 can be performed intermittently during all three phases, during only preheating phase 1110, during only first charge phase 1120, during only second charge phase 1130, or any combination thereof. For example, monitoring routine 1400 can be performed once every 5 seconds, 10 seconds, 20 seconds, or any other desired interval. Routine 1400 can include the application of one pair of pulses (e.g., 1404 and 1405) or multiple pairs. The pulse length can range from 0.1 ms to 10 seconds, preferably on the order of 100 ms or less so as to minimally impact the charge time of routine 1400.
Referring back to
The battery cells used to collect the data of
The protocol embodiments described with respect to
In the example system configuration 2010 of
The example system configuration 2020 of
In the example configuration 2030 of
In the example configuration 2040 of
In the example configuration 2050 of
In the example configuration 2060 of
While not limited to such, configurations 2010, 2020, and 2030 may be particularly suitable for relatively lower voltage applications (e.g., 10 watt-hours to 20 kilowatt-hours (kWh)), while configurations 2040 and 2050 may be particularly suitable for relatively higher (moderate) voltage applications (e.g., 20 kWh to 100 kWh), and configuration 2060 may be particularly suitable for relatively higher voltage applications (e.g., 100 kWh and greater).
The embodiments described herein can also be used to charge an EV power train with the energy created from a regenerative braking system of the EV. For example, during braking the generated power can be applied to the power train as a pulse train, either by switching circuitry electrically located between the regenerative braking system and the electric power train (e.g., in the case of a conventional non-switchable serially connected battery pack) or with converters 202 integrated within modules 108 as in the case of a cascaded converter system 100. The management of the switching to generate the appropriate pulse train can be under the control of a control system of the EV, such as control system 102 (e.g., MCD 112).
Example Charging and Heating Embodiments Based on Impedance, Inductance, and/or Thermal Characteristic Information
The following example embodiments describe performance of preheating phase 1110 and/or pulse charging phase 1120 of protocol 1100 based on assessed impedance and/or inductance information of the subject one or more energy sources 206. In addition, or alternatively, preheating phase 1110 can be performed based on assessed thermal characteristics such as thermal impedance and/or thermal capacitance of the subject one or more energy sources 206. These embodiments can be performed by, or under the direction of, a controller 2101 which can include processing circuitry and memory and can be configured as a single device or multiple devices. Controller 2101 can be associated with any of the systems described herein, including those systems based on a modular cascaded system 100 and those that are not, such as the various configurations 2010-2060 described with respect to
At step 2104, controller 2101 can assess one or more impedances of the subject sources 206, including total impedance, ohmic impedance, and/or activation impedance. Impedance can be measured generally with one or more stimulus signals in any manner known to those of ordinary skill in the art. In some examples, impedance is measured by electrochemical impedance spectroscopy (EIS) using a voltage or current frequency stimulus pulse generator, data capturing circuitry and impedance estimation processing circuitry included with controller 2101. Total impedance, as well as activation and ohmic impedances can also be measured by application of a stimulus signal (e.g., a current pulse) and measurement of the resulting voltage response, including the total voltage drop and the voltage drop components η*ohmic and η*act corresponding to the ohmic impedance (Rohmic) and the activation impedance (RCT+RWarburg) respectively (see
At step 2106, controller 2101 can assess an inductance of the charging path between the charge source and the subject sources 206. Like impedance, inductance can be measured in any manner known to those of ordinary skill in the art. In some examples, inductance is measured by electrochemical impedance spectroscopy (EIS) using a voltage or current frequency sweep pulse generator, response data capturing circuitry and inductance estimation processing circuitry included with controller 2101. Total inductance can also be measured by application of a current pulse and measurement of the resulting voltage response, or alternatively with application of a voltage pulse and evaluation of the current response. Inductance can be measured at the terminals (e.g., a first node and a second node) where the charging signal is output from charge source 150 to the system containing the subject sources 206.
At step 2108, controller 2101 can assess one or more thermal aspects of the subject sources 206. This can include a measurement of the temperature of the subject sources 206, such as by using a temperature sensing device on, in, or in close proximity with the subject sources 206. This measured temperature can be indicative of an internal temperature of the subject sources 206. An external or ambient temperature can also or alternatively be measured, which is indicative of the temperature of the environmental surroundings of controller 2101. Furthermore, a thermal resistance and/or a thermal capacitance of the subject sources 206 can be measured. Thermal resistance can be measured by application of one or more preheating pulses to the subject sources 206 to generate a certain amount of local heating, and then measuring the temperature response of the subject sources 206. Based on the temperature increase response and time constant of increase, the capacity can be estimated. The thermal resistivities can be determined based on thermal circuit models or thermal finite element simulation based models as known in the art.
Steps 2102-2108 can be performed in any desired order and are not limited to the sequence shown in
In some embodiments one or more of the impedance, inductance, thermal resistance, and thermal capacitance of the subject sources 206 can be characterized in development or after manufacturing, and those characterized parameters can be utilized in selecting and programming the appropriate frequencies, currents (e.g., C rates), current limits, temperature limits, voltages, and/or voltage limits, for preheating phase 1110, pulse charging phase 1120, and/or charge phase 1130 (to the extent applicable). In such embodiments, the assessment of those parameters in one or more of steps 2104-2108 can be omitted.
In some embodiments, controller 2101 can be configured to recognize the subject sources 206 as a model type, class of products, or chemistry based on an identifier (e.g., bit string), and reference a data structure (e.g., a data array or look up table) containing the associated characteristics (e.g., impedance, inductance, thermal characteristics) for the subject sources 206 based on the model type or class, thereby avoiding the need to perform in field assessments of those parameters such as in steps 2104-2108. In some cases the data structure can include the parameters for performance of protocol 1100 (e.g., heating signal frequency, pulse charge signal frequency, currents (e.g., C rates), current limits, temperature limits, voltages, and/or voltage limits, for preheating phase 1110, pulse charging phase 1120, and/or charge phase 1130 (to the extent applicable)). Recognition of the model type, class, or chemistry can be performed by reading an identifier or other indication from a local memory associated with the source 206, such as a battery management system, or by retrieval from a cloud-based server (over a wired or wireless internet connection). Alternatively, the source 206 can have an identifier tag antenna that can be read by a local reader of controller 2101, such as using near field communication (NFC) or RFID. In another example, the type, class, or chemistry can be manually uploaded or input into controller 2101.
Instead of relying on model type or class, the subject sources can be characterized prior to deployment in the field, such as during the manufacturing or testing process prior to commercial distribution, and the characterized information (e.g., impedance, inductance, thermal characteristics) can be digitally stored and associated with the subject sources 206, such as in the local memory of a battery management system associated with the subject sources 206, or in a server located in a cloud network. The characterized information can be retrieved locally from the local memory (e.g., via a communication bus) or from a cloud-based server (e.g., over a wireless or wired internet connection) and utilized to determine the appropriate parameters for performance of protocol 1100 (e.g., frequencies, currents (e.g., C rates), current limits, temperature limits, voltages, and/or voltage limits, for preheating phase 1110, pulse charging phase 1120, and/or charge phase 1130 (to the extent applicable)). Retrieval from a cloud-based server can involve controller 2101 reading or receiving one or more serial numbers or other unique identifiers of the subject sources 206 (or a data location identifier) and communicating that identifying information to the cloud-based server, which can respond with the characterized information and/or protocol performance parameters. Instead of or in addition to communication of the characterized parameters, the protocol performance parameters (e.g., frequencies, currents (e.g., C rates), current limits, temperature limits, voltages, and/or voltage limits, for preheating phase 1110, pulse charging phase 1120, and/or charge phase 1130 (to the extent applicable)) can be communicated to controller 2101 over either the local communication connection or the wireless or wired internet connection.
At step 2110, controller 2101 can perform a validation or verification to determine whether the subject sources 206 are in a state suitable for performance of protocol 1100. Any one or more of the assessed parameters (total impedance, activation impedance, ohmic impedance, inductance, source temperature, exterior temperature, thermal resistance, thermal capacitance) can be compared to a validation condition, such as a minimum and/or maximum threshold limit (e.g., a threshold range) of acceptable values for that parameter. For example, it can be determined whether activation impedance falls within a threshold range of acceptable or permissible activation impedances, and if it does fall within that range, then the condition is satisfied and controller 2101 can proceed to assessment of the next parameter. This process can proceed until all parameters have been validated. If any one or more parameters violates the validation condition, then controller 2101 can determine not to perform the corresponding phase of protocol 1100. For example, if the thermal resistance is too high, then controller 2101 can determine not to perform preheating phase 1110, or if the activation impedance is too high, then controller 2101 can determine not to perform pulse charge phase 1120, and instead proceed with a constant current charge at a relatively low current.
At step 2112, controller 2101 can then select protocol settings (e.g., values, ranges, or limits) for performance of protocol 1100 based on the assessed parameters. The protocol settings can include a value or range (upper and lower limits) of acceptable values for fpreheat, fpulse, the current amplitude for application in a positive and negative preheat pulse 1112, the current for application in a charge pulse 1122, the voltage for application in a positive and negative preheat pulse 1112, the voltage amplitude for application in charge pulse 1122, and/or a duty cycle of the preheat or pulse signals 1112 and 1122. The protocol settings can also include acceptable values or ranges for monitored responses from source 206 during performance of protocol 1100, such as an acceptable voltage level in the voltage response 1212 (e.g., peak total voltage, anode overvoltage, cathode overvoltage), acceptable impedances (e.g., total impedance, activation impedance, ohmic impedance), a maximum source temperature, a maximum rate of rise of source temperature, and an acceptable concentration gradient (e.g., concentration overvoltages). Each phase 1110, 1120, and 1130 of protocol 1100 can have multiple different values or ranges for a particular setting, and can cycle through these values or ranges as controller 2101 progresses through the particular phase (e.g., iteratively increasing or decreasing applied current in pulses 1122 as controller 2101 progresses through phase 1120).
In one embodiment, controller 2101 causes the assessment of an impedance of the subject source 206 before or during preheating phase 1110, which is then used to determine a voltage or current amplitude for heating signal 1112. If the assessed impedance is greater than an impedance threshold, then a relatively low amplitude can be selected, or if preheating phase 1110 is already commenced, the amplitude of the heating signal can be decreased to slow the rate of heating. If the assessed impedance is less than the impedance threshold, then a relatively high amplitude can be selected, or if preheating phase 1110 is already commenced, the amplitude of the heating signal can be increased to accelerate heating.
At step 2114, controller 2101 can implement the one or more validated phases 1110, 1120, 1130 of protocol 1100 using the selected protocol settings. Each phase of protocol 1100 can be performed in its entirety with these settings, or the settings can be periodically adjusted as the phase progresses, such as to adjust for increasing SOC. Controller 2101 can perform assessment steps 2102, 2104, 2106, and/or 2108 periodically throughout each phase of protocol 1100. The assessed parameters can be used to repeat validation step 2110 and/or to revise the protocol settings. For example, while applying a preheat pulse train 1112, controller 2101 can periodically cause application of a current pulse 1214 and instruct measurement of the voltage response 1212 to assess equilibrated activation and ohmic overvoltages (or impedances) to assess whether pulse charging is suitable, and/or to update stored values for activation and/or ohmic impedances. Also, while applying charge pulses 1122, controller 2101 can periodically cause application of a current pulse 1214 (of the same or similar amperage) and instruct measurement of the voltage response 1212 to assess the activation voltage drop (n*act), and the ohmic voltage drop (η*ohmic). Controller 2101 can then adjust the applied current or voltage signal amplitudes and/or frequencies based on the assessed feedback in the particular phase. Method 2100 can continue until the subject sources 206 are adequately heated and/or charged.
Example Embodiments of Charging with Detection of Voltage Shifts Due to Concentration Changes
The embodiments described herein can be performed to charge the subject sources 206 while accounting for the voltage shifts due to concentration changes. These voltage shifts are due to the increase of the open circuit cell voltage due to lower concentration on the electrode (e.g., Nernst overvoltage) and the increase of the reaction rate losses due to lower concentration at the interface (e.g., activation overvoltage). Alleviation of the Nernst overvoltage requires back diffusion towards equilibrium and typically takes much longer than alleviation of the activation overvoltage.
The Nernstian overvoltage due to concentration shift (ηconc-Nernst) can be derived from the Nernst equation for a single reactant species (neglecting product accumulation) and is given by (9), where R is the universal gas constant (8.314 J K−1 mol−1), T is temperature in Kelvin, n is the quantity of electrons involved in the electrochemical reaction (e.g., lithium main reaction is a simple one electron transfer reaction), and F is the Faraday constant (number of coulombs per mole of electrons, 96485.33 C mol−1):
and the activation overvoltage due to concentration shift (ηconc-activation) can be derived from the Butler-Volmer equation and at high current density can be simplified as expressed in (10):
The two components of the concentration induced overvoltage are related by inverse of the term α, which is the charge transfer coefficient, dimensionless with typical values between 0.3-0.7 and dependent on the reversibility of the reaction. The total overvoltage due to concentration change (ηconc) is given by (11):
ηconc=ηconc-Nernst−ηconc-activation=(E*Nernst−E0Nernst)+(n*act−η0act). (11)
If ηconc is known, it can be used to verify that application of an overvoltage during pulse charging does not exceed the permissible anode and cathode overvoltage ranges. Values for E0Nernst, and η0act can be determined through characterization (as will be described below), or can be assessed in the field (e.g., measured while in use in an EV), during manufacturing or test prior to distribution, modeled through software, or based on a standard value for the source type or class. The values can then be stored or programmed into controller 2101.
The value for η*act can be measured in voltage response 1212 (see
While possible, measurement of the value for E*Nernst is difficult to perform during a charging phase due to the relatively long duration involved. However because ηconc-activation can be determined and is equivalent to the product of (1/α) and ηconc-Nernst, then an estimation of a can be used to calculate the value of ηconc-Nernst. Further, c0 is typically known (e.g., 1.0-1.5 mol for lithium ion batteries), which permits a calculation of the concentration gradient (c0/c*) using (9) or (10), which in turn allows the regulation of the charging process based on concentration gradient if desired.
Equilibrium impedance data structures (e.g., a data array or look up table) can be constructed with values for R0ohmic and R0CT at equilibrium as functions of SOC (e.g., 0-90%) and temperature (e.g., −20 to 50 degrees C.). A visual representation of an example look up table is shown below in Table 2. Each cross-referenced grid location (x1 through x80) can be populated with the corresponding value of R0ohmic and/or R0CT at that specific SOC and temperature. Here, SOC and temperature are delineated in increments of 10, but in other embodiments finer (or courser) increments of SOC and temperature can be used to provide the level of granularity desired for the implementation. The values of R0ohmic and R0CT can be determined by characterizing the subject source (or a representative source) using a current pulse and voltage response technique (see
The value for η0ohmic can be calculated by selecting the value of R0ohmic at the current (or nearest) values of SOC and temperature of the subject source 206 and multiplying by the current of the applied pulse 1214 which may vary (η0ohmic=IpulseR0ohmic(SOC,T)). The amperage of the applied current pulse 1214 can be the same or can be similar to the amperage of the charge current being used during the respective phase (e.g., pulse 1122). Similarly, the value for η0act can be calculated by selecting the value of R0act at the current (or nearest) values of SOC and temperature of the subject source 206 and multiplying by the current of the applied pulse 1214 (η0act=ImeasurementR0act(SOC,T)).
The equilibrium impedance data structures can be stored as data or program instructions in memory local to the subject sources (e.g., a BMS) or retrieved from a cloud server using the techniques described herein. In some embodiments, the system having sources 206 can perform assessment or characterization of the sources 206 in the field and use the data to construct or revise these data structures.
ηconc_activation(SOC)<f(SOC) (12)
ηconc_Nernst(SOC)<1/αf(SOC) (13)
ηconc(SOC)<[1+(1/α)]f(SOC) (14)
f(SOC)=[R′ηconc max anode(SOC)]/[1+(1/α)] (15)
where R′ is a ratio factor dependent on the distribution of the overall activation impedance between the anode and cathode. For example, an R′ value of two equates to impedances that are evenly distributed between anode and cathode. The value of R′ can be selected based on testing or modeling of the actual chemistries of the subject sources and their electrodes. Because f(SOC) is scaled by the term [1+(1/α)], the charge process can be regulated using only ηconc_activation and use of ηconc_Nernst is not required, though it can be used if desired in some embodiments. TABLE 3 includes example values for f(SOC) based on an R′ of two, a value of 0.5 for α, and values of 210 mV, 180 mV, and 85 mV for V1, V2, and V3.
The ηconc max anode values can be selected as desired for the implementation. For example, these values can be central tendency values (e.g., averages or medians) across each discrete SOC range, or can be minimums within the range so as to lessen the likelihood of an excessive anode overvoltage condition. Of course these values are merely examples and will vary with source chemistry, type, and age, and the like.
In other embodiments, f(SOC) can be based on concentration gradient (c0/c*), e.g., as determined using (9) or (10). The charge phase 1120 or 1130 can be performed and the concentration gradient can be periodically assessed and charging parameters adjusted to ensure that the gradient does not become too large.
Intermittently during the charge step 2402, controller 2101 can initiate an assessment step 2404 to determine ηconc_activation, which according to (10) is η*act minus η0act. The intermittent interval can be based on an elapsed time (e.g., every 10 seconds, 20 seconds, 30 seconds, etc.), based on the occurrence of a charge or temperature condition (e.g., every 1% change in SOC level, every one degree rise in temperature), based on the amount of change in applied voltage required to drive the desired current, or based on the amount of change of applied current based on a constant applied voltage (e.g., indicating a concentration change).
In an example embodiment, to determine ηconc_activation, the R0act(SOC,T) value can first be identified from the corresponding data structure (e.g., Table 2) using the SOC and temperature values that the subject source 206 is at (or is nearest), which can be assessed at the same time as step 2404 or estimated based on an earlier assessment of SOC and temperature. η0act can be determined by taking the product of this identified R0act(SOC,T) value and the current of an applied current pulse 1214. η*act can be determined in any of the manners described herein. For example, the R0ohmic(SOC,T) value can be identified from the corresponding data structure (e.g., Table 2) using the SOC and temperature values that the subject source 206 is at (or is nearest). η0ohmic can be determined by taking the product of this identified R0ohmic(SOC,T) value and the current of an applied current pulse 1214. η*ohmic can be assumed to be the same as η0ohmic (or scaled to be slightly different) given that the variation in ohmic voltage drop due to concentration change is small. This η*ohmic value can then be subtracted from the measured voltage drop during T_fall, with the resultant difference being η*act. Subtraction of η0act from η*act can then yield ηconc_activation.
At step 2406, controller 2101 can determine whether ηconc_activation indicates that the charge current should be adjusted. Controller 2101 can select the appropriate f(SOC) threshold value from a corresponding data structure (e.g., Table 3) based on the present SOC of the subject source 206, and compare this f(SOC) threshold value to ηconc_activation. If ηconc_activation exceeds the threshold value then this can be indicative of too high of a charge current applied (such as one that generates an overvoltage on the anode beyond the permissible range), and controller 2101 can determine to adjust one or more charging parameters, such as reducing the charge current, adjusting fpulse (if during phase 1120), or adjusting a duty cycle or pulse width of the charge pulse 1122 (if during phase 1120), to reduce the overvoltage generated on the anode and cathode. If ηconc_activation is the same as, or slightly below, the threshold value then this can be indicative of an appropriate amount of a charge current applied, and controller 2101 can determine to maintain the charging parameters without adjustment. If ηconc_activation is significantly below the threshold value then this can be indicative of too little charge current applied (such as there being additional overvoltage available on the anode without exceeding the permissible range), and controller 2101 can determine to adjust the one or more charging parameters, such as increasing the charge current, adjusting fpulse (if during phase 1120), or adjusting a duty cycle or pulse width of the charge pulse 1122 (if during phase 1120), to increase the overvoltage generated on the anode and cathode.
At 2408, controller can determine the amount of the adjustment and proceed back to charge step 2402. The amount of the adjustment can be set to a fixed value. The fixed value can be a relatively small value so as to conservatively adjust current during the charge process. Alternatively, controller 2101 can select an adjustment amount that is in proportion to the difference between ηconc_activation and the threshold f(SOC) value, e.g., scale the adjusted parameter by the amount of difference.
Method 2400 can iteratively perform pulse charging and ηconc_activation assessments and adjustments until the target SOC level is reached (step 2410), or until the appropriate transition condition is reached for transition from pulse charge phase 1120 to constant current charge phase 1130 as described with respect to protocol 1100 herein. Constant current charging 1130 can be performed with intermittent assessments of ηconc_activation and charge parameter adjustments (e.g., charge current) as described in steps 2404, 2406, and 2408. In this manner, method 2400 can proceed through either or both of charge phases 1120 and 1130 with high current until the subject sources reach the target SOC level.
Steps 2422, 2424, and 2426 are used to verify that the subject source 206 under equilibrium is in suitable condition for a high current fast pulse charging phase 1120, and may be omitted in certain embodiments if unnecessary or undesired. At step 2422, the subject source 206 temperature can be measured and preheating phase 1110 can be performed to raise the source 206 temperature, e.g., to a value at which there is R0ohmic and R0act data in the equilibrium impedance data structures. At step 2424, a measurement of η0ohmic and η0act can be performed by application of a current pulse 1214 and measurement of the voltage response 1212 across the T_rise (e.g., 50-100 ms). At step 2426, R0ohmic′ and R0act′ can be determined based on the measured 1L ohmic and η0act and the applied current and compared to the preexisting values for R0ohmic and R0act in the equilibrium impedance data structures (or alternatively the comparison can be of the corresponding ohmic and activation voltages). Based on the comparison, a condition for proceeding with fast charging is or is not validated. If the values are commensurate, then method 2420 can proceed towards high current fast charging at step 2430. If the newly measured R0ohmic′ and R0act′ values (or voltages) are significantly higher (e.g., above a threshold), then this can be indicative of significant aging in the subject source 206 and a normal current, slower charging procedure can be performed instead at 2428.
At step 2430, the subject source 206 temperature can be measured (again if desired) and preheating phase 1110 can be performed to raise the source 206 temperature to the desired starting temperature for pulse charge phase 1120 (or phase 1130). At step 2432, the pulse charge phase 1120 can be initiated or otherwise performed and can proceed with intermittent assessments of ηconc_activation at 2434. Controller 2101 can determine whether an adjustment to charging parameters should be made at step 2436, and the adjustment magnitude can be determined at step 2438, at which point method 2420 can revert to pulse charging at step 2432. Steps 2432, 2434, 2436, and 2438 are similar to steps 2402, 2404, 2406, and 2408 described with respect to
Method 2420 can iteratively perform pulse charging and ηconc_activation assessments and adjustments until the target SOC level is reached, or until the appropriate transition condition is reached for transition from pulse charge phase 1120 to constant current charge phase 1130. Constant current charging 1130 can be also performed with intermittent assessments of ηconc_activation and charge parameter adjustments (e.g., charge current) as described in steps 2404, 2406, and 2408. In this manner, method 2420 can proceed through either or both of charge phases 1120 and 1130 with high current until the subject sources reach the target SOC level, e.g., 80%, as shown in step 2440.
Referring back to step 2426, in some embodiments the equilibrium impedance data structures can be updated based on the newly collected data. For example, the reassessed values for R0ohmic′ and R0act′ can be compared to the corresponding two values in the equilibrium impedance data structure. A scaling factor SFohmic can be derived based on the proportional difference between R0ohmic′ and the R0ohmic value in the data structure, and this scaling factor can be used to scale all of the R0ohmic values in the data structure across SOC and temperature, such that R0ohmic′ (SOC, T)=SFohmic×R0ohmic (SOC, T). Similarly, a scaling factor SFact can be derived based on the proportional difference between R0act′ and the R0act value in the data structure, and this scaling factor can be used to scale all of the R0act values in the data structure across SOC and temperature, such that R0act′ (SOC, T)=SFact×R0act (SOC, T). In this manner the ohmic and activation impedances can be periodically updated over the lifetime of the subject sources 206 to ensure accuracy in staying within anode and cathode permissible overvoltage ranges.
Methods 2100, 2400 and 2420 can be performed for modular cascaded systems 100. The performance of these methods in a cascaded system 100 can entail the method's performance individually and discretely for each energy source within the system. Thus, for a system having N modules, the method 2100, 2400, 2420 can be performed N times to tailor the method for each specific energy source (e.g., based on the SOC, temperature, impedance, inductance, and/or thermal characteristics of the subject individual source). The N instances of the method can be performed concurrently with each other under the control of control system 102 (alone or in conjunction with a control unit of the accompanying charge source 150).
When performed within modular cascaded systems 100, the embodiments described herein can be used to charge all such modules of the systems, including modules 108-1 through 108-N of each array, and interconnection modules 108IC, for all such modules having one, two, or more energy sources therein.
While many of the embodiments are described herein in the context of a current controlled charge signal (e.g., an applied current pulse), all such embodiments can likewise be implemented with a voltage controlled charge signal (e.g., an applied voltage pulse).
All of the aforementioned embodiments pertaining to pulsed charging can be implemented according to a pulse width modulated control scheme or a hysteresis based control scheme as described herein, with additional constraints as to pulse length implemented where applicable so as not to violate pulse duration conditions of certain embodiments described herein.
All of the aforementioned embodiments pertaining to fast charging can likewise be used to discharge the system in a fast manner as well.
In all of the embodiments described herein, the primary energy source of each module of a particular system can have the same voltage (either standard operating voltage or nominal voltage). Such a configuration simplifies management and Construction of the system. The primary and second energy sources can also have the same voltage (standard or nominal). Other configurations can be implemented, such as those where primary energy sources of different modules of the same system have different voltages (standard or nominal), and those where the primary and secondary energy sources of a module have different voltages (standard or nominal). Still other configurations can be implemented, where primary energy sources of modules of a system have primary energy source batteries that are different chemistries, or where modules of the system have a primary energy source battery of a first chemistry, and a secondary energy source battery of a second chemistry. The modules that differ from each other can be based on placement in the system (e.g., modules within a phase array are different than the IC module(s)).
Various aspects of the present subject matter are set forth below, in review of, and/or in supplementation to, the embodiments described thus far, with the emphasis here being on the interrelation and interchangeability of the following embodiments. In other words, an emphasis is on the fact that each feature of the embodiments can be combined with each and every other feature unless explicitly stated or taught otherwise.
In a first group of embodiments, a method of charging an energy source is provided, the method including: applying a charge signal to an energy source such that a concentration shift occurs within the energy source; measuring a voltage response to a current pulse applied to the energy source; determining, from the voltage response, an activation overvoltage due to the concentration shift; and determining whether to adjust a parameter of the charge signal based, at least in part, on the activation overvoltage due to the concentration shift.
In some embodiments of the first group, the measured voltage response is a voltage drop occurring after termination of the current pulse over a time period (T_fall). The measured voltage response can include a first voltage drop due to ohmic loss (η*ohmic) and a second voltage drop due to activation loss (η*act). The time period can be 150 milliseconds or less. The activation overvoltage due to concentration shift (ηconc-activation) can be determined by: subtracting the first voltage drop due to ohmic loss from the measured voltage response to yield the second voltage drop due to activation loss; and subtracting an equilibrium voltage loss due to activation loss (η0act) from the second voltage drop due to activation loss to yield the activation overvoltage due to concentration shift. The method can include determining the first voltage drop due to ohmic loss based on an equilibrium voltage loss due to ohmic loss (η0ohmic). The method can include determining the equilibrium voltage loss due to ohmic loss from an equilibrium ohmic impedance (R0ohmic) stored in memory. A plurality of equilibrium ohmic impedances can be stored in memory with associated state of charge values and/or temperature values.
In some embodiments of the first group, the method can include determining the equilibrium voltage loss due to activation loss from an equilibrium activation impedance (R0CT) stored in memory. A plurality of equilibrium activation impedances can be stored in memory with associated state of charge values and/or temperature values. The equilibrium ohmic impedances and equilibrium activation impedances are stored in at least one data structure. The at least one data structure can be a data array or a look up table. The method can include assessing at least one of a state of charge and temperature of the energy source and referencing the memory with the assessed at least one state of charge and/or temperature to determine the equilibrium ohmic impedance and equilibrium activation impedance. Both the state of charge and temperature can be assessed and used in referencing the memory.
In some embodiments of the first group, the method includes adjusting the parameter of the charge signal. The parameter can be at least one of: a charge current amperage, a frequency of pulses of the charge signal, a duty cycle of pulses of the charge signal, or a duration of pulses of the charge signal.
In some embodiments of the first group, determining whether to adjust a parameter of the charge signal based, at least in part, on the activation overvoltage due to the concentration shift, includes: comparing the activation overvoltage due to concentration shift (ηconc-activation) with a threshold (f(SOC)). The method can include increasing the charge current amperage if the activation overvoltage is less than the threshold. The method can include decreasing the charge current amperage if the activation overvoltage exceeds the threshold. The method can include maintaining the charge current amperage unadjusted if the activation overvoltage is commensurate with the threshold. The method can include determining the threshold. Determining the threshold can include selecting a threshold based on a present state of charge of the energy source. The method can include referencing a data structure having a plurality of thresholds each associated with one or more state of charge levels. The threshold accounts for both activation loss due to concentration shift (η*act) and Nernstian loss due to concentration shift (η*Nernst). The threshold can be based on a permissible range of anode overvoltage or a maximum anode overvoltage. The threshold can be a voltage value.
In some embodiments of the first group, the method can include: determining at least one of an updated equilibrium ohmic impedance and an updated equilibrium activation impedance; comparing the at least one of the updated equilibrium ohmic impedance and the updated equilibrium activation impedance to a corresponding at least one preexisting equilibrium ohmic impedance and preexisting equilibrium activation impedance; and determining whether to apply the charge signal. If the at least one of the updated equilibrium ohmic impedance and the updated equilibrium activation impedance is within a range of the corresponding at least one preexisting equilibrium ohmic impedance and preexisting equilibrium activation impedance, then the method can include determining to apply the charge signal. The method can include: assessing a temperature of the energy source; and preheating the energy source to a target temperature, prior to determining the at least one of the updated equilibrium ohmic impedance and the updated equilibrium activation impedance.
In some embodiments of the first group, the method includes: assessing a temperature of the energy source; preheating the energy source to a target temperature; performing a validation assessment to determine whether to proceed to charging. The validation assessment can include: measuring a parameter of the energy source at the target temperature; comparing the measured parameter to a pre-existing version of the parameter; and determining whether to proceed to charging.
In some embodiments of the first group, the applied charge signal is either a plurality of charge pulses or a constant current charge signal.
In some embodiments of the first group, the energy source is a lithium ion battery cell.
In some embodiments of the first group, the energy source is a battery module including a plurality of lithium ion cells connected together in a series and/or parallel fashion.
In some embodiments of the first group, the energy source is a battery of an electric vehicle.
In a second group of embodiments, a system configured to charge an energy source is provided, the system including: the energy source; and a controller configured to: control application of a charge signal to the energy source such that a concentration shift occurs within the energy source; control measurement of a voltage response to a current pulse applied to the energy source; determine, from the voltage response, an activation overvoltage due to the concentration shift in the energy source; and determine whether to adjust a parameter of the charge signal based, at least in part, on the activation overvoltage due to the concentration shift.
In some embodiments of the second group, the controller can be configured to determine the activation overvoltage by: subtraction of a first voltage drop due to ohmic loss from the measured voltage response to yield a second voltage drop due to activation loss; and subtraction of an equilibrium voltage loss due to activation loss from the second voltage drop due to activation loss to yield the activation overvoltage due to concentration shift. The controller can be configured to determine the first voltage drop due to ohmic loss based on an equilibrium voltage loss due to ohmic loss. The controller can be configured to determine the equilibrium voltage loss due to ohmic loss from an equilibrium ohmic impedance stored in a memory of the controller. A plurality of equilibrium ohmic impedances can be stored in the memory with associated state of charge values and/or temperature values.
In some embodiments of the second group, the controller can be configured to determine the equilibrium voltage loss due to activation loss from an equilibrium activation impedance stored in the memory.
In some embodiments of the second group, the controller can be configured to control assessment of at least one of a state of charge and temperature of the battery module and reference the memory with the assessed at least one state of charge and/or temperature to determine the equilibrium ohmic impedance and equilibrium activation impedance.
In some embodiments of the second group, the controller can be configured to adjust the parameter of the charge signal.
In some embodiments of the second group, the controller can be configured to compare the activation overvoltage due to concentration shift with a threshold to determine whether to adjust a parameter of the charge signal. The controller can be configured to determine the threshold. The controller can be configured to select the threshold based on a present state of charge of the energy source.
In some embodiments of the second group, the controller can be configured to: determine at least one of an updated equilibrium ohmic impedance and an updated equilibrium activation impedance; compare the at least one of the updated equilibrium ohmic impedance and the updated equilibrium activation impedance to a corresponding at least one preexisting equilibrium ohmic impedance and preexisting equilibrium activation impedance; and determine whether to apply the charge signal.
In some embodiments of the second group, the controller can be configured to: cause assessment of a temperature of the battery module; control application of a preheating signal to the battery module to raise the battery module to a target temperature; and perform a validation assessment to determine whether to charge the battery module. To perform the validation assessment, the controller can be configured to: control of a measurement of a parameter of the energy source at the target temperature; compare the measured parameter to a pre-existing version of the parameter; and determine whether to charge the energy source based on the comparison.
In some embodiments of the second group, the charge signal is either a plurality of charge pulses or a constant current charge signal.
In some embodiments of the second group, the energy source includes a lithium ion battery cell.
In some embodiments of the second group, the controller includes processing circuitry and memory having a plurality of instructions that, when executed by the processing circuitry, cause the processing circuitry to execute the steps of the method, or cause the steps of the method to be performed.
In a third group of embodiments, a system configured to charge an energy source is provided, the system including: a plurality of converter modules, each converter module including a converter and a battery module coupled with the converter, the battery module having a plurality of battery cells connected in series and/or parallel, where the plurality of converter modules are coupled together in at least one array configured to generate a voltage including a superposition of output signals from each of the converter modules; and a control system configured to: control application of a charge signal to each battery module such that a concentration shift occurs within the battery cells of the battery module; control measurement of a voltage response to a current pulse applied to each battery module; determine, from the voltage response, an activation overvoltage due to the concentration shift in the battery cells of the battery module; and determine whether to adjust a parameter of the charge signal based, at least in part, on the activation overvoltage due to the concentration shift.
In some embodiments of the third group, the measured voltage response is a voltage drop occurring after termination of the current pulse over a time period. The measured voltage response can include a first voltage drop due to ohmic loss and a second voltage drop due to activation loss. The time period can be 150 milliseconds or less. The control system can be configured to determine the activation overvoltage by: subtraction of the first voltage drop due to ohmic loss from the measured voltage response to yield the second voltage drop due to activation loss; and subtraction of an equilibrium voltage loss due to activation loss from the second voltage drop due to activation loss to yield the activation overvoltage due to concentration shift. The control system can be configured to determine the first voltage drop due to ohmic loss based on an equilibrium voltage loss due to ohmic loss. The control system can be configured to determine the equilibrium voltage loss due to ohmic loss from an equilibrium ohmic impedance stored in a memory of the control system. A plurality of equilibrium ohmic impedances are stored in the memory with associated state of charge values and/or temperature values. The control system can be configured to determine the equilibrium voltage loss due to activation loss from an equilibrium activation impedance stored in the memory. The memory stores a plurality of equilibrium activation impedances with associated state of charge values and/or temperature values. The memory stores at least one data structure having the equilibrium ohmic impedances and equilibrium activation impedances. The at least one data structure can be a data array or a look up table. The control system can be configured to control assessment of at least one of a state of charge and temperature of the battery module and reference the memory with the assessed at least one state of charge and/or temperature to determine the equilibrium ohmic impedance and equilibrium activation impedance. The control system can be configured to assess both the state of charge and temperature.
In some embodiments of the third group, the control system can be configured to adjust the parameter of the charge signal. The parameter can be at least one of: a charge current amperage, a frequency of pulses of the charge signal, a duty cycle of pulses of the charge signal, or a duration of pulses of the charge signal.
In some embodiments of the third group, the control system can be configured to compare the activation overvoltage due to concentration shift with a threshold to determine whether to adjust a parameter of the charge signal. The control system can be configured to instruct increase of the charge current amperage if the activation overvoltage is less than the threshold. The control system can be configured to instruct decrease of the charge current amperage if the activation overvoltage exceeds the threshold. The control system can be configured to instruct maintenance of the charge current amperage if the activation overvoltage is commensurate with the threshold. The control system can be configured to determine the threshold. The control system can be configured to select a threshold based on a present state of charge of the energy source. The control system can be configured to reference a data structure including a plurality of thresholds each associated with one or more state of charge levels. The threshold can account for both activation loss due to concentration shift and Nernstian loss due to concentration shift. The threshold can be based on a permissible range of anode overvoltage. The threshold can be a voltage value.
In some embodiments of the third group, the control system can be configured to: determine at least one of an updated equilibrium ohmic impedance and an updated equilibrium activation impedance; compare the at least one of the updated equilibrium ohmic impedance and the updated equilibrium activation impedance to a corresponding at least one preexisting equilibrium ohmic impedance and preexisting equilibrium activation impedance; and determine whether to apply the charge signal. The control system can be configured to determine to apply the charge signal if the at least one of the updated equilibrium ohmic impedance and the updated equilibrium activation impedance is within a range of the corresponding at least one preexisting equilibrium ohmic impedance and preexisting equilibrium activation impedance. The control system can be configured to: cause measurement of a temperature of the battery module; and control application of a preheating signal to the battery module to raise the battery module to a target temperature.
In some embodiments of the third group, the control system can be configured to: cause assessment of a temperature of the battery module; control application of a preheating signal to the battery module to raise the battery module to a target temperature; perform a validation assessment to determine whether to charge the battery module. To perform the validation assessment, the control system can be configured to: control of a measurement of a parameter of the energy source at the target temperature; compare the measured parameter to a pre-existing version of the parameter; and determine whether to charge the energy source based on the comparison.
In some embodiments of the third group, the charge signal can be either a plurality of charge pulses or a constant current charge signal.
In some embodiments of the third group, the battery cells are lithium ion battery cells.
In some embodiments of the third group, the plurality of converter modules are configured to supply power to a motor of an electric vehicle.
In a fourth group of embodiments, a method of heating of an energy source is provided, the method including: determining an inductance and/or an impedance of an energy source by application of at least one stimulus signal to the energy source; determining a frequency for a heating signal based on the determined inductance and/or impedance of the energy source; and applying the heating signal to the energy source at the frequency.
In some embodiments of the fourth group, the heating signal can be configured to heat the energy source without substantially charging the energy source.
In some embodiments of the fourth group, the heating signal includes a series of pulses of alternating polarity.
In some embodiments of the fourth group, the heating signal does not apply a net charge to the energy source.
In some embodiments of the fourth group, the inductance is determined, and the inductance is based on a measurement across at least a first node and a second node, and the inductance includes the inductance of the energy source and conductive paths between the first node and the second node. The inductance can be determined with either spectroscopy or by the application of a current pulse and measurement of a voltage response.
In some embodiments of the fourth group, the energy source can be a battery pack including a plurality of battery cells, and the inductance includes the inductance of the battery cells, conductive paths between the battery cells, and conductive paths between measurement nodes and one or more of the battery cells.
In some embodiments of the fourth group, the method can be performed for a system having a plurality of converter modules, each converter module including a converter and the energy source coupled with the converter, the energy source being a battery module having a plurality of battery cells connected in series and/or parallel, where the plurality of converter modules are coupled together in at least one array configured to generate a voltage including a superposition of output signals from each of the converter modules. The method can include: determining an inductance and/or an impedance of each energy source of the system by application of at least one stimulus signal to each energy source; for each energy source, determining a frequency for a heating signal based on the determined inductance and/or impedance of each energy source; and for each energy source, applying the heating signal to each energy source at the frequency determined for that energy source.
In some embodiments of the fourth group, the impedance can be determined and the impedance can be a total impedance of the energy source.
In some embodiments of the fourth group, the method includes determining the activation impedance and total impedance of the energy source.
In some embodiments of the fourth group, the frequency can be determined such that it exceeds a minimum frequency based on the impedance, and such that it does not exceed a maximum frequency based on the inductance. Both the inductance and impedance are determined and used to select the frequency. The frequency can be selected from a data structure based on the determined inductance and impedance. The data structure can be a look up table.
In a fifth group of embodiments, a method of charging of an energy source is provided, the method including: determining an inductance and/or an impedance of an energy source by application of at least one stimulus signal to the energy source; determining a frequency for a charging signal based on the determined inductance and/or impedance of the energy source; and applying the charging signal to the energy source at the frequency.
In some embodiments of the fifth group, the charging signal includes a plurality of charge pulses.
In some embodiments of the fifth group, the inductance is determined, and the inductance is based on a measurement across a first node and a second node, and the inductance includes the inductance of the energy source and conductive paths between the first node and the second node. The inductance can be determined with either spectroscopy or by the application of a current pulse and measurement of a voltage response.
In some embodiments of the fifth group, the energy source can be a battery pack having a plurality of battery cells, and the inductance includes the inductance of the battery cells, conductive paths between the battery cells, and conductive paths between measurement nodes and one or more of the battery cells.
In some embodiments of the fifth group, the method can be performed for a system including a plurality of converter modules, each converter module having a converter and the energy source coupled with the converter, the energy source being a battery module having a plurality of battery cells connected in series and/or parallel, where the plurality of converter modules are coupled together in at least one array configured to generate a voltage including a superposition of output signals from each of the converter modules. The method can include: determining an inductance and/or an impedance of each energy source of the system by application of at least one stimulus signal to each energy source; for each energy source, determining a frequency for a charging signal based on the determined inductance and/or impedance of each energy source; and for each energy source, applying the charging signal to each energy source at the frequency determined for that energy source.
In some embodiments of the fifth group, the impedance is determined and the impedance is a total impedance of the energy source.
In some embodiments of the fifth group, the method includes determining the activation impedance and total impedance of the energy source.
In some embodiments of the fifth group, the frequency can be determined such that it exceeds a minimum frequency based on the impedance, and such that it does not exceed a maximum frequency based on the inductance. Both the inductance and impedance are determined and used to select the frequency. The frequency can be selected from a data structure based on the determined inductance and impedance. The data structure can be a look up table.
In a sixth group of embodiments, a method of charging of an energy source is provided, the method including: assessing a plurality of impedances of the energy source where the plurality of impedances includes a total impedance and a non-ohmic impedance; and applying a charge signal to the energy source, where the charge signal includes pulses at a frequency that maintains the non-ohmic impedances above a threshold proportion of the total impedance.
In some embodiments of the sixth group, the threshold proportion can be 50%.
In some embodiments of the sixth group, the threshold proportion can be 60%.
In some embodiments of the sixth group, the non-ohmic impedance includes an activation impedance, and a Warburg impedance.
In some embodiments of the sixth group, the charge signal can be applied at a time average C rate of two or greater.
In some embodiments of the sixth group, the charge signal can be applied at a 50% duty cycle.
In some embodiments of the sixth group, the charge signal can be applied at a 40-60% duty cycle.
In a seventh group of embodiments, a method of heating an energy source is provided, the method including: assessing an impedance of the energy source during a preheating phase of the energy source, where the preheating phase includes applying a heating signal at a first frequency to the energy source; determining a second frequency for the heating signal based on the assessed impedance; and applying the heating signal at the second frequency to the energy source.
In some embodiments of the seventh group, the heating signal can be configured to heat the energy source without substantially charging the energy source.
In some embodiments of the seventh group, the heating signal includes a series of pulses of alternating polarity.
In some embodiments of the seventh group, the heating signal does not apply a net charge to the energy source.
In an eighth group of embodiments, a method of charging in a system is provided, where the system includes a plurality of converter modules, each converter module including a converter and an energy source coupled with the converter, the energy source being a battery module having a plurality of battery cells connected in series and/or parallel, where the plurality of converter modules are coupled together in at least one array configured to generate a voltage including a superposition of output signals from each of the converter modules, the method including: assessing, for each energy source individually, an impedance the energy source during a pulse charge phase of the system, where the pulse charge phase includes applying pulse charge signals to the energy sources; determining an adjusted frequency for a pulse charge signal of at least one energy source based on the assessed impedance for that energy source; and applying the pulse charge signal at the adjusted frequency to the at least one energy source.
In some embodiments of the eighth group, the impedance can be a total impedance of the energy source.
In some embodiments of the eighth group, assessing, for each energy source individually, an impedance the energy source includes assessing the activation impedance and total impedance for each energy source. The method can include determining the adjusted frequency for the pulse charge signal of at least one energy source based on the assessed activation and total impedances for that energy source.
In a ninth group of embodiments, a method related to charging of an energy source is provided, the method including: assessing a parameter of an energy source; identifying a frequency corresponding to the assessed parameter by reference to a data structure; and applying a signal at the identified frequency to the energy source, where the signal can be configured to either: charge the energy source; or heat the energy source without substantially charging the energy source.
In some embodiments of the ninth group, the parameter can be an impedance of the energy source.
In some embodiments of the ninth group, the parameter can be a identifier for the energy source.
In a tenth group of embodiments, a method related to charging of an energy source is provided, the method including: assessing a parameter, where the parameter is a state of charge of an energy source, an impedance of the energy source, a temperature of the energy source, or a temperature external to the energy source; determining an amplitude of a heating signal based on at least the assessed parameter; and applying the heating signal at the amplitude to the energy source.
In some embodiments of the tenth group, the parameter can be an impedance of the energy source, and determining the amplitude of the heating signal based on at least the assessed impedance includes decreasing the amplitude if the assessed impedance is greater than an impedance threshold.
In some embodiments of the tenth group, the parameter can be an impedance of the energy source, and determining the amplitude of the heating signal based on at least the assessed impedance includes increasing the amplitude if the assessed impedance is less than an impedance threshold.
In some embodiments of the tenth group, the energy source includes a lithium ion battery cell.
In some embodiments of the tenth group, the energy source can be a battery module including a plurality of battery cells connected in serial and/or parallel.
In some embodiments of the tenth group, the method can be performed in a system including a control system and a plurality of cascaded converter modules and energy sources, where the method can be performed independently for each energy source and concurrently by the plurality of converter modules.
In an eleventh group of embodiments, a method of heating an energy source is provided, the method including applying an electrical heating signal to the energy source, where the electrical heating signal includes a sequence of alternating charge and discharge pulses at a frequency that heats an ohmic portion of the energy source without substantially heating a non-ohmic portion of the energy source.
In some embodiments of the eleventh group, the energy source includes a lithium ion cell.
In some embodiments of the eleventh group, the electrical heating signal can be applied while monitoring a temperature of the energy source and a temperature of an environment exterior to the energy source. The electrical heating signal can be applied such that a gradient between the temperature of the energy source and an environment exterior to the energy source is maintained within a threshold limit. The threshold limit can be 30 degrees Celsius or the threshold limit can be 20 degrees Celsius.
In some embodiments of the eleventh group, the method can be performed without simultaneously cooling the energy source with a cooling apparatus.
In a twelfth group of embodiments, a method related to charging an energy source is provided, the method including: assessing the charge level of a subject energy source to be charged; assessing at least one of an impedance of the energy source or an inductance of a charge path including the energy source; selecting a protocol setting for performance of a heating and/or charging protocol on the subject source based on the assessed impedance and/or inductance; and performing the protocol on the subject source.
In some embodiments of the twelfth group, the impedance is assessed, and the method includes assessing at least one of a total impedance, activation impedance, or ohmic impedance of the subject source. The impedance can be measured with electrochemical impedance spectroscopy. The impedance can be measured by application of a stimulus signal and measurement of a voltage response.
In some embodiments of the twelfth group, the inductance is assessed.
In some embodiments of the twelfth group, the method can include assessing at least one thermal aspect of the subject source. The at least one thermal aspect can be a temperature of the subject source or a temperature of an ambient environment external to the subject source. The at least one thermal aspect can be a thermal resistance or a thermal capacitance of the subject source. The thermal resistance is assessed, and the thermal resistance is assessed by application of one or more preheating pulses to the subject sources to generate an amount of local heating from which thermal resistance is determined.
In some embodiments of the twelfth group, the method can include recognizing an identifier of a model type, product class, or chemistry of the subject source. The method can include: referencing a data structure including a parameter of the recognized model type, product class, or chemistry of the subject source; and selecting the protocol setting based on the parameter. The method can include selecting the protocol setting by reference to a data structure including the protocol setting for the identifier of the model type, product class, or chemistry of the subject source. The method can include sending the identifier of the recognized model type, product class, or chemistry of the subject source to a cloud based server and receiving a parameter of the subject source or a protocol setting from the cloud based server.
In some embodiments of the twelfth group, the method can include: reading an identifier of the subject source; sending the identifier to a cloud-based server; and receiving a parameter of the subject source or a protocol setting from the cloud-based server.
In some embodiments of the twelfth group, the method can include reading a parameter of the subject source or a protocol setting from a local memory of the subject source.
In some embodiments of the twelfth group, the method can include performing a validation whether a preheating phase and/or charging phase can be performed on the subject source. The validation can include comparing a parameter of the subject source with a validation condition. The parameter can be an activation impedance.
In some embodiments of the twelfth group, selecting the protocol setting includes selecting at least one of: a value or a range for a frequency of a heating signal, a value or a range for a frequency of a pulse charging signal, a value or a range for current or voltage amplitude for the heating signal, a value or a range for current or voltage amplitude for the pulse charging signal, a duty cycle of the heating signal, a duty cycle of the pulse charging signal, a pulse width of the heating signal, or a pulse width of the pulse charging signal.
In some embodiments of the twelfth group, the method can include performing a preheating phase of the protocol on the subject source.
In some embodiments of the twelfth group, the method can include performing a pulse charging phase of the protocol on the subject source.
In some embodiments of the twelfth group, the method can include performing a constant current charging phase of the protocol on the subject source.
In some embodiments of the twelfth group, the protocol includes preheating the subject source, pulse charging the subject source, and constant current charging the subject source.
In some embodiments of the twelfth group, the subject source can be a battery module within an electric vehicle.
In some embodiments of the twelfth group, the method can be performed by or under the direction of a controller or control system.
In some embodiments of the twelfth group, the subject source includes a lithium ion battery cell.
In some embodiments of the twelfth group, the subject source can be a battery module having a plurality of lithium ion battery cells connected in series and/or parallel.
The term “module” as used herein refers to one of two or more devices or subsystems within a larger system. The module can be configured to work in conjunction with other modules of similar size, function, and physical arrangement (e.g., location of electrical terminals, connectors, etc.). Modules having the same function and energy source(s) can be configured identical (e.g., size and physical arrangement) to all other modules within the same system (e.g., rack or pack), while modules having different functions or energy source(s) may vary in size and physical arrangement. While each module may be physically removable and replaceable with respect to the other modules of the system (e.g., like wheels on a car, or blades in an information technology (IT) blade server), such is not required. For example, a system may be packaged in a common housing that does not permit removal and replacement any one module, without disassembly of the system as a whole. However, any and all embodiments herein can be configured such that each module is removable and replaceable with respect to the other modules in a convenient fashion, such as without disassembly of the system.
The term “master control device” is used herein in a broad sense and does not require implementation of any specific protocol such as a master and slave relationship with any other device, such as the local control device.
The term “output” is used herein in a broad sense, and does not preclude functioning in a bidirectional manner as both an output and an input. Similarly, the term “input” is used herein in a broad sense, and does not preclude functioning in a bidirectional manner as both an input and an output.
The terms “terminal” and “port” are used herein in a broad sense, can be either unidirectional or bidirectional, can be an input or an output, and do not require a specific physical or mechanical structure, such as a female or male configuration.
Processing circuitry can include one or more processors, microprocessors, controllers, and/or microcontrollers, each of which can be a discrete or stand-alone chip or distributed amongst (and a portion of) a number of different chips. Any type of processing circuitry can be implemented, such as, but not limited to, personal computing architectures (e.g., such as used in desktop PC's, laptops, tablets, etc.), programmable gate array architectures, proprietary architectures, custom architectures, and others. Processing circuitry can include a digital signal processor, which can be implemented in hardware and/or software. Processing circuitry can execute software instructions stored on memory that cause processing circuitry to take a host of different actions and control other components.
Processing circuitry can also perform other software and/or hardware routines. For example, processing circuitry can interface with communication circuitry and perform analog-to-digital conversions, encoding and decoding, other digital signal processing, multimedia functions, conversion of data into a format (e.g., in-phase and quadrature) suitable for provision to communication circuitry, and/or can cause communication circuitry to transmit the data (wired or wirelessly).
Processing circuitry can also be adapted to execute the operating system and any software applications, and perform those other functions not related to the processing of communications transmitted and received.
Computer program instructions for carrying out operations in accordance with the described subject matter may be written in any combination of one or more languages, including computer and programming languages. A non-exhaustive list of examples includes hardware description languages (HDLs), SystemC, C, C++, C#, Objective-C, Matlab, Simulink, SystemVerilog, SystemVHDL, Handel-C, Python, Java, JavaScript, Ruby, HTML, Smalltalk, Transact-SQL, XML, PHP, Golang (Go), “R” language, and Swift, to name a few.
Memory, storage, and/or computer readable media can be shared by one or more of the various functional units present, or can be distributed amongst two or more of them (e.g., as separate memories present within different chips). Memory can also reside in a separate chip of its own.
To the extent the embodiments disclosed herein include or operate in association with memory, storage, and/or computer readable media, then that memory, storage, and/or computer readable media are non-transitory. Accordingly, to the extent that memory, storage, and/or computer readable media are covered by one or more claims, then that memory, storage, and/or computer readable media is only non-transitory. The terms “non-transitory” and “tangible” as used herein, are intended to describe memory, storage, and/or computer readable media excluding propagating electromagnetic signals, but are not intended to limit the type of memory, storage, and/or computer readable media in terms of the persistency of storage or otherwise. For example, “non-transitory” and/or “tangible” memory, storage, and/or computer readable media encompasses volatile and non-volatile media such as random access media (e.g., RAM, SRAM, DRAM, FRAM, etc.), read-only media (e.g., ROM, PROM, EPROM, EEPROM, flash, etc.) and combinations thereof (e.g., hybrid RAM and ROM, NVRAM, etc.) and variants thereof.
It should be noted that all features, elements, components, functions, and steps described with respect to any embodiment provided herein are intended to be freely combinable and substitutable with those from any other embodiment. If a certain feature, element, component, function, or step is described with respect to only one embodiment, then it should be understood that that feature, element, component, function, or step can be used with every other embodiment described herein unless explicitly stated otherwise. This paragraph therefore serves as antecedent basis and written support for the introduction of claims, at any time, that combine features, elements, components, functions, and steps from different embodiments, or that substitute features, elements, components, functions, and steps from one embodiment with those of another, even if the following description does not explicitly state, in a particular instance, that such combinations or substitutions are possible. It is explicitly acknowledged that express recitation of every possible combination and substitution is overly burdensome, especially given that the permissibility of each and every such combination and substitution will be readily recognized by those of ordinary skill in the art.
As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
While the embodiments are susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that these embodiments are not to be limited to the particular form disclosed, but to the contrary, these embodiments are to cover all modifications, equivalents, and alternatives falling within the spirit of the disclosure. Furthermore, any features, functions, steps, or elements of the embodiments may be recited in or added to the claims, as well as negative limitations that define the inventive scope of the claims by features, functions, steps, or elements that are not within that scope.
This application claims the benefit of, and priority to, U.S. Provisional Application No. 63/325,509, filed Mar. 30, 2022, which is incorporated by reference herein in its entirety and for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63325509 | Mar 2022 | US |
