Patent Application
20220190619
The subject matter described herein relates generally to pulsed charging of energy sources in energy storage systems used in both mobile and stationary applications.
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 battery pack or rack 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 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, it is well known that lengthy charge times for electric vehicles (EVs) are a major factor limiting their wide spread adoption. 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. For these and other reasons, needs exist for improved systems, devices, and methods for fast or rapid charging of electrical energy storage systems.
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 to drive 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 C 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 certain 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 an energy source and switch circuitry capable of applying current in a pulsed manner for preheating and/or charging. Embodiments for monitoring the energy source to detect potentially degradatory conditions such as uneven lithiation and lithium plating are also disclosed.
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. It is also to be understood that 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 charging and discharging modular energy systems, it is first useful to describe these underlying systems 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 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.
In describing embodiments herein, reference may be made to a particular stationary application (e.g., grid, micro-grid, data centers, cloud computing environments) or mobile application (e.g., an electric car). Such references are made for ease of explanation and do not mean that a particular embodiment is limited for use to only that particular mobile or stationary application. Embodiments of systems providing power to a motor can be used in both mobile and stationary 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.
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, from which system 102 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, 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, MDC 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.
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 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 (system 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
Module 108 can include one or more energy sources and a power electronics converter and, if desired, an energy buffer.
Converter 202 can be 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. The fuel cell can be a single fuel cell, multiple fuel cells connected in series or parallel, or a fuel cell module. Two or more energy sources can be included in each module, and the two or more sources can include two batteries of the same or different type, two capacitors of the same or different type, two fuel cells of the same or different type, one or more batteries combined with one or more capacitors and/or fuel cells, and one or more capacitors combined with one or more fuel cells.
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. Examples of fuel cells 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 type (e.g., each can be a battery), or a different type (e.g., a first source can be a battery and a second source can be an HED capacitor, or a first source can be a battery having a first type (e.g., NMC) and a second source can be a battery having a second type (e.g., LFP).
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 node 1 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
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 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 realtively 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 systems 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 108IC. 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 108IC 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 108IC 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 108IC 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 108IC 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 108IC can be electrically connected with each other module 108IC by way of I/O ports 3 and 4, which are coupled with the energy source 206 of each module 108IC as described with respect to module 108C of
Each module 108IC 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 108IC applies energy to multiple arrays 700 (
Example embodiments will now be described herein relating to fast charging techniques for energy sources using pulse preheating 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 having multiple battery modules (e.g., connected in series, parallel, or a combination thereof, sometimes referred to as a battery pack).
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 fast or rapid charging of energy sources at improved speeds. 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,
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
preheat>>1/(RCT*CDL). (1)
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 1 hertz (Hz) up to 1 megahertz (Mhz). In various embodiments preheating signal 1112 has a frequency range between 100 Hz and 100 kilohertz (kHz). The frequency of preheating signal 1112 causes the voltage drop to occur primarily by action of the electrolyte impedance and the current collector impedance, and thus the voltage of preheating signal 1112 can lead to cathode and anode voltages that exceed their relative cut off overvoltages at both relatively low and relatively high states of charge.
Preheating phase 1110 causes a temperature increase at local regions within the battery cells by targeting 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 warms the cell until the activation impedance and total impedance is small enough so 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 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 fast 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.
First charge phase 1120 is a pulse charging phase where a pulse charge signal is applied to battery 206. Phase 1120 allows fast 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 cutoff voltages (upper and lower) of energy source 206. In some embodiments, the amount that the phase 1120 pulses can exceed the cut off voltage is equal to or less than the pulse charge current times the activation impedance for the electrode.
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 (2):
F
pulse>1/(RCT*CDL). (2)
Fpulse values above twice that of equation (2) substantially eliminate activation impedance and activation overvoltage (e.g., eliminate the VA and RCT components of
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 overvoltages.
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 VA, RCT, VNernst, and RWarburg components of
The constant current can be applied at a relatively high time average C rate such as 4 C-8 C (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
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).
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 many embodiments, a method for charging an energy source is provided, the method including: applying a preheating signal including a sequence of alternating charge and discharge energy pulses to the energy source such that the temperature of the energy source increases; and then applying a charging signal to the energy source such that the charge of the energy source increases.
In some embodiments, the preheating signal is applied until the energy source reaches a first temperature, and the charging signal is applied after the energy source reaches the first temperature.
In some embodiments, the preheating signal is applied for a first time duration, and the charging signal is applied after the first time duration.
In some embodiments, the preheating signal has a frequency such that no electrochemical storage reaction nor side reaction takes place in the energy source.
In some embodiments, the energy source is a lithium ion battery and the preheating signal has a frequency greater than one kilohertz.
In some embodiments, the preheating signal has a frequency such that electrochemical charge transfer of a main storage reaction and side reactions of the energy source are bypassed. The method where the electrochemical charge transfer can be bypassed by the interface capacities of electrodes of the energy source to an electrolyte of the energy source.
In some embodiments, the charging signal includes a plurality of charge pulses. The method where the plurality of charge pulses can have pulse durations less than or equal to ten milliseconds, less than or equal to five milliseconds, or less than or equal to two milliseconds. The method where the energy source can have an open circuit voltage and an upper cutoff voltage, and where the plurality of charge pulses can be at a voltage between the open circuit voltage and the upper cutoff voltage.
In some embodiments, the charging signal is a first charging signal including a plurality of pulses, the method can further include: applying a second charging signal to the energy source after applying the first charging signal, where the second charging signal can be a constant current charging signal. The method where the preheating signal can be applied until the energy source reaches a first temperature, the first charging signal can be applied until the energy source reaches a second temperature, and the second charging signal can be applied after the energy source reaches the second temperature. The method where the first temperature can be 25 degrees Celsius or higher, or between 25 degrees and 40 degrees Celsius. The method where the second temperature can be 45 degrees Celsius or higher, or between 45 degrees and 55 degrees Celsius. The method where the first charging signal can be applied until the energy source reaches a first state of charge, and the second charging signal can be applied after the energy source reaches the first state of charge. The method where the second charging signal can be applied until the energy source reaches a state of charge of 95% or higher. The method where the energy source can have a state of charge of 5% or less at a first time that the first charging signal is applied, where the energy source can have a state of charge of 75% or greater at a second time after the second charging signal is applied, and where the difference between the first time and the second time can be ten minutes or less. The method where the preheating signal can be applied for two minutes or less before application of the first charging signal.
In some embodiments, the energy source is a battery including lithium, the method can further include monitoring the energy source for lithium plating. The method where monitoring the energy source for lithium plating can include determining whether a voltage response of the energy source to application of a charge pulse followed by a discharge pulse including a lithium stripping signature. The method where monitoring the energy source for lithium plating can include: applying a charge pulse immediately followed by a discharge pulse to the energy source; performing a derivation of a voltage response to at least the discharge pulse; and determining whether the derivation includes a lithium stripping signature. The method where monitoring the energy source for lithium plating can be performed intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the method can further include monitoring an impedance of the energy source for an indication of degradation. The method can further include adjusting application of the charging signal in response to the monitored impedance. The method where monitoring an impedance of the energy source can be performed intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the energy source is a battery cell.
In some embodiments, the energy source is a battery module including a plurality of battery cells.
In some embodiments, the charging signal includes a plurality of charge pulses, and application of the preheating signal is stopped and application of the charging signal is commenced when a Warburg impedance of an electrode of the energy source is 20% or less of the total impedance of the electrode.
In some embodiments, the charging signal includes a plurality of charge pulses, and application of the preheating signal is stopped and application of the charging signal is commenced when a Warburg impedance of an electrode of the energy source is 10% or less of the total impedance of the electrode.
In some embodiments, the charging signal includes a plurality of charge pulses, and application of the preheating signal is stopped and application of the charging signal is commenced when a Warburg impedance of an electrode times an average current of the charging signal is less than an available overvoltage of the electrode.
In some embodiments, the charging signal is a constant current charging signal, and application of the preheating signal is stopped and application of the charging signal is commenced when an activation impedance of an electrode of the energy source is 20% or less of the total impedance of the electrode.
In some embodiments, the charging signal is a constant current charging signal, and application of the preheating signal is stopped and application of the charging signal is commenced when an activation impedance of an electrode of the energy source is 10% or less of the total impedance of the electrode.
In some embodiments, application of the first charging signal is stopped and application of the second charging signal is commenced when an activation impedance of an electrode of the energy source is 50% or less of the total impedance of the electrode.
In some embodiments, application of the first charging signal is stopped and application of the second charging signal is commenced when an activation impedance of an electrode of the energy source is 20% or less of the total impedance of the electrode.
In some embodiments, application of the first charging signal is stopped and application of the second charging signal is commenced when an activation impedance of an electrode of the energy source is 10% or less of the total impedance of the electrode.
In some embodiments, the pulse preheating signal is applied at a voltage greater than an upper cutoff voltage and a lower cutoff voltage of the energy source.
In some embodiments, the charging signal includes a plurality of charge pulses at peak voltages greater than a cutoff voltage of the energy source.
In many embodiments, a system configured to charge an energy source is provided, the system including: a control system configured to: (a) control switch circuitry to apply a preheating signal to an energy source such that a temperature of the energy source increases until the energy source satisfies a condition, where the preheating signal includes a sequence of alternating charge and discharge energy pulses; and (b) control the switch circuitry to apply a charging signal to the energy source after the energy source satisfies the condition.
In some embodiments, the control system includes processing circuity communicatively coupled with a memory, where the memory stores instructions that, when executed by the processing circuitry, cause the control system to perform steps (a) and (b).
In some embodiments, the control system is further configured to detect when the energy source satisfies the condition or receive an indication that the energy source satisfied the condition.
In some embodiments, the condition is a temperature condition, the control system being configured to control switch circuitry to apply the preheating signal until the energy source reaches a first temperature, and to apply the charging signal after the energy source reaches the first temperature.
In some embodiments, the control system is configured to control switch circuitry to apply the preheating signal for a first time duration, and to apply the charging signal after the first time duration.
In some embodiments, the preheating signal has a frequency configured to prevent an electrochemical storage reaction and side reaction from occurrence in the energy source.
In some embodiments, the energy source is a lithium ion battery and the preheating signal has a frequency greater than one kilohertz.
In some embodiments, the preheating signal has a frequency configured to bypass electrochemical charge transfer of a main storage reaction and side reactions of the energy source.
In some embodiments, the charging signal includes a plurality of charge pulses.
In some embodiments, the plurality of charge pulses have pulse durations less than or equal to ten milliseconds. The system where the plurality of charge pulses can have pulse durations less than or equal to five milliseconds or less than or equal to two milliseconds. The system where the energy source can have an open circuit voltage and an upper cutoff voltage, and where the plurality of charge pulses are at a voltage between the open circuit voltage and the upper cutoff voltage.
In some embodiments, the charging signal is a first charging signal including a plurality of pulses, and where the control system is configured to control switch circuitry to apply a second charging signal to the energy source after application of the first charging signal, where the second charging signal is a constant current charging signal. The system where the control system can be configured to control switch circuitry to apply the preheating signal until the energy source reaches a first temperature, to apply the first charging signal until the energy source reaches a second temperature, and to apply the second charging signal after the energy source reaches the second temperature. The system where the first temperature can be 25 degrees Celsius or higher, or between 25 degrees and 40 degrees Celsius. The system where the second temperature can be 45 degrees Celsius or higher, or between 45 degrees and 55 degrees Celsius. The system where the control system is configured control switch circuitry to apply the first charging signal until the energy source reaches a first state of charge, and to apply the second charging signal after the energy source reaches the first state of charge. The system where the control system can be configured to control switch circuitry to apply the second charging signal until the energy source reaches a state of charge of 95% or higher.
In some embodiments, the energy source is a battery including lithium, and where the control system is configured to monitor the energy source for lithium plating. The system where the control system can be configured to determine whether a voltage response of the energy source to application of a charge pulse is followed by a discharge pulse that includes a lithium stripping signature.
In some embodiments, the control system is configured to: control switch circuitry to apply a charge pulse to the energy source immediately followed by a discharge pulse; perform a derivation of a voltage response to at least the discharge pulse; and determine whether the derivation includes a lithium stripping signature. The system where the control system can be configured to monitor the energy source for lithium plating intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the control system is configured to monitor an impedance of the energy source for an indication of degradation. The system where the control system can be configured to control switch circuitry to adjust application of the charging signal in response to the monitored impedance. The system where the control system can be configured to monitor an impedance of the energy source intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the energy source is a battery cell.
In some embodiments, the energy source is a battery module including a plurality of battery cells.
In many embodiments, a method of charging a plurality of energy sources within an energy storage system is provided, where the energy storage system includes a plurality of modules connected together in cascaded fashion, each of the plurality of modules including an energy source and switch circuitry, where the energy storage system is configured to generate AC power with a superposition of output signals generated by the plurality of modules, the method including: applying, by the switch circuitry of each module, a preheating signal including a sequence of alternating charge and discharge energy pulses to the energy source of each module such that the temperature of the energy source of each module increases; and then applying, by the switch circuitry of each module, a charging signal to the energy source of each module.
In some embodiments, the preheating signal is applied until the energy source reaches a first temperature, and the charging signal is applied after the energy source reaches the first temperature.
In some embodiments, the energy source includes a plurality of cells, and the preheating signal is applied until all cells reach a first minimum temperature or until at least one cell reaches a maximum temperature.
In some embodiments, the preheating signal is applied for a first time duration, and the charging signal is applied after the first time duration.
In some embodiments, the charging signal includes a plurality of charge pulses. The method where the plurality of charge pulses can have pulse durations less than or equal to ten milliseconds, less than or equal to five milliseconds, or less than or equal to two milliseconds. The method where the energy source of each module can have an open circuit voltage and an upper cutoff voltage, and where the plurality of charge pulses are at a voltage between the open circuit voltage and the upper cutoff voltage.
In some embodiments the charging signal is a first charging signal including a plurality of charge pulses, the method can further include : applying, by the switch circuitry of each module, a second charging signal to the energy source of each module after applying the first charging signal, where the second charging signal is a constant current charging signal. The method where the preheating signal can be applied until the energy source reaches a first temperature, the first charging signal can be applied until the energy source reaches a second temperature, and the second charging signal can be applied after the energy source reaches the second temperature. The method where the first temperature can be 25 degrees Celsius or higher, or between 25 degrees and 40 degrees Celsius. The method where the second temperature can be 41 degrees Celsius or higher, or between 41 degrees and 60 degrees Celsius. The method where the first charging signal can be applied until the energy source reaches a first state of charge, and the second charging signal can be applied after the energy source reaches the first state of charge. The method where the second charging signal can be applied until the energy source reaches a state of charge of 95% or higher. The method where the energy source can have a state of charge of 5% or less at a first time that the first charging signal is applied, where the energy source can have a state of charge of 75% or greater at a second time after the second charging signal is applied, and where the difference between the first time and the second time can be ten minutes or less. The method where the preheating signal can be applied for two minutes or less before application of the first charging signal.
In some embodiments, the energy source of each module is a battery including lithium, the method can further include monitoring the energy source of each module for lithium plating. The method where monitoring the energy source of each module for lithium plating can include determining whether a voltage response of the energy source to application of a charge pulse followed by a discharge pulse includes a lithium stripping signature. The method where monitoring the energy source of each module for lithium plating can include: applying a charge pulse immediately followed by a discharge pulse to the energy source; performing a derivation of a voltage response to at least the discharge pulse; and determining whether the derivation includes a lithium stripping signature. The method where monitoring the energy source of each module for lithium plating can be performed intermittently during a charging phase of the energy source of each module where the charging signal is applied. The method can further include monitoring an impedance of the energy source at each module for an indication of degradation. The method can further include adjusting application of the charging signal in response to the monitored impedance. The method where monitoring an impedance of the energy source at each module can be performed intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the energy source is a battery cell.
In some embodiments, the energy source is a battery module including a plurality of battery cells.
In many embodiments, an energy storage system is provided, including: a plurality of modules connected together in cascaded fashion, each of the plurality of modules including an energy source and switch circuitry, where the energy storage system is configured to generate AC power with a superposition of output signals generated by the plurality of modules, where the energy storage system is configured to, for each module: (a) control the switch circuitry to apply a preheating signal to the energy source such that a temperature of the energy source increases until the energy source reaches a first temperature, where the preheating signal includes a sequence of alternating charge and discharge energy pulses; and (b) control the switch circuitry to apply a charging signal to the energy source when the energy source is at or above the first temperature.
In some embodiments, the system can further include a control system configured to perform (a) and (b). The system where the control system can include a master control device and a plurality of local control devices associated with the plurality of modules, where the master control device is communicatively coupled with the plurality of local control devices, and where the plurality of local control devices are configured to output switching control signals to the switch circuitry of the plurality of modules.
In some embodiments, the system can further include processing circuity communicatively coupled with a memory, where the memory stores instructions that, when executed by the processing circuitry, cause the system to perform (a) and (b).
In some embodiments, the system can be configured to control switch circuitry to apply the preheating signal until the energy source reaches a first temperature, and to apply the charging signal after the energy source reaches the first temperature.
In some embodiments, the system can be configured to control switch circuitry to apply the preheating signal for a first time duration, and to apply the charging signal after the first time duration.
In some embodiments, the preheating signal has a frequency configured to prevent an electrochemical storage reaction and side reaction from occurrence in the energy source.
In some embodiments, the energy source is a lithium ion battery and the preheating signal has a frequency greater than one kilohertz.
In some embodiments, the preheating signal has a frequency configured to bypass electrochemical charge transfer of a main storage reaction and side reactions of the energy source.
In some embodiments, the charging signal includes a plurality of charge pulses. The system where the energy source has an open circuit voltage and an upper cutoff voltage, and where the plurality of charge pulses are at a voltage between the open circuit voltage and the upper cutoff voltage.
In some embodiments, the charging signal is a first charging signal including a plurality of pulses, and where the control system is configured to control switch circuitry to apply a second charging signal to the energy source after application of the first charging signal, where the second charging signal is a constant current charging signal. The system where the control system can be configured to control switch circuitry to apply the preheating signal until the energy source reaches a first temperature, to apply the first charging signal until the energy source reaches a second temperature, and to apply the second charging signal after the energy source reaches the second temperature. The system where the control system can be configured control switch circuitry to apply the first charging signal until the energy source reaches a first state of charge, and to apply the second charging signal after the energy source reaches the first state of charge. The system where the control system can be configured to control switch circuitry to apply the second charging signal until the energy source reaches a state of charge of 95% or higher.
In some embodiments, the energy source is a battery including lithium, and where the control system is configured to monitor the energy source for lithium plating. The system where the control system can be configured to determine whether a voltage response of the energy source to application of a charge pulse followed by a discharge pulse includes a lithium stripping signature.
In some embodiments, the control system is configured to: control switch circuitry to apply a charge pulse to the energy source immediately followed by a discharge pulse; perform a derivation of a voltage response to at least the discharge pulse; and determine whether the derivation includes a lithium stripping signature. The system where the control system can be configured to monitor the energy source for lithium plating intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the control system is configured to monitor an impedance of the energy source for an indication of degradation. The system where the control system can be configured to control switch circuitry to adjust application of the charging signal in response to the monitored impedance. The system where the control system is configured to monitor an impedance of the energy source intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, every energy source is a battery cell.
In some embodiments, every energy source is a battery module including a plurality of battery cells.
In some embodiments, the plurality of modules is a first plurality of modules, and the system further includes: a second plurality of modules connected together in cascaded fashion, each of the second plurality of modules including an energy source and switch circuitry, where the energy storage system is configured to generate AC power with a superposition of output signals generated by the second plurality of modules; and a third plurality of modules connected together in cascaded fashion, each of the third plurality of modules including an energy source and switch circuitry, where the energy storage system is configured to generate AC power with a superposition of output signals generated by the third plurality of modules, where the AC power includes three phase AC power. The system where the system can be configured to power a motor of an automotive electric vehicle.
In many embodiment, a method of charging an energy source is provided, the method including: applying a preheating signal including a sequence of alternating charge and discharge energy pulses to the energy source such that the temperature of the energy source increases, where the preheating signal is at a frequency that passes through a double layer capacitance of the energy source.
In some embodiments, the double layer capacitance includes a double layer capacitance of an anode of the energy source and a double layer capacitance of a cathode of the energy source.
In some embodiments, the preheating signal does not substantially charge the energy source.
In some embodiments, the preheating signal is applied for a first time duration such that the energy source is heated without being substantially charged, and then the preheating signal is applied for a second time duration such that the energy source is heated and charged. Durations of the charge energy pulses can be incrementally increased during the second time duration relative to the discharge energy pulses.
In some embodiments, the energy source is a battery cell.
In some embodiments, the energy source is a battery module including a plurality of battery cells.
In some embodiments, the preheating signal is applied until the energy source reaches a first temperature, and the charging signal is applied after the energy source reaches the first temperature.
In some embodiments, the preheating signal is applied for a first time duration, and the charging signal is applied after the first time duration.
In some embodiments, the preheating signal has a frequency such that no electrochemical storage reaction nor side reaction takes place in the energy source.
In some embodiments, the energy source is a lithium ion battery and the preheating signal has a frequency greater than one kilohertz.
In some embodiments, the preheating signal has a frequency such that electrochemical charge transfer of a main storage reaction and side reactions of the energy source are bypassed. The method where the electrochemical charge transfer can be bypassed by the interface capacities of electrodes of the energy source to an electrolyte of the energy source.
In many embodiments, a method of monitoring a battery including lithium for the occurrence of lithium plating is provided, the method including: applying a charge pulse followed by a discharge pulse to the battery; and determining whether a voltage response of the battery to application of the charge pulse followed by the discharge pulse includes a lithium stripping signature.
In some embodiments, where determining whether the voltage response includes a lithium stripping signature includes: performing a derivation of the voltage response of the battery to at least the discharge pulse; and determining whether the derivation includes a lithium stripping signature. The method where the lithium stripping signature can be a transition in the derivation while the discharge pulse is applied.
In some embodiments, where determining whether the voltage response includes a lithium stripping signature includes determining whether a variation in the voltage response during application of the discharge pulse is greater than a threshold.
In some embodiments, the method is performed intermittently during a charging phase of the battery.
In some embodiments, the battery includes a single battery cell.
In some embodiments, the battery includes a plurality of battery cells.
In many embodiments, a method of charging an energy source is provided, the method including: applying a first charging signal comprising charge pulses to the energy source, wherein a duration of each charge pulse is less than ten milliseconds; determining when the energy source satisfies a transition condition; and applying a second charging signal to the energy source after determining satisfaction of the transition condition, wherein the second charging signal is a constant current charging signal.
In some embodiments, the duration of each charge pulse is less than or equal to five milliseconds.
In some embodiments, the duration of each charge pulse is less than or equal to two milliseconds.
In some embodiments, the energy source has an open circuit voltage and an upper cutoff voltage, and the charge pulses are at a voltage between the open circuit voltage and the upper cutoff voltage.
In some embodiments, the transition condition is a state of charge threshold.
In some embodiments, the energy source is a battery comprising lithium, the method further including monitoring the energy source for lithium plating.
In some embodiments, monitoring the energy source for lithium plating includes determining whether a voltage response of the energy source to application of a charge pulse followed by a discharge pulse comprises a lithium stripping signature.
In some embodiments, monitoring the energy source for lithium plating includes: applying a charge pulse immediately followed by a discharge pulse to the energy source; performing a derivation of a voltage response to at least the discharge pulse; and determining whether the derivation comprises a lithium stripping signature.
In some embodiments, monitoring the energy source for lithium plating is performed intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the method further includes monitoring an impedance of the energy source for an indication of degradation.
In some embodiments, the method further includes adjusting application of the charging signal in response to the monitored impedance.
In some embodiments, monitoring an impedance of the energy source is performed intermittently during a charging phase of the energy source where the charging signal is applied.
In some embodiments, the transition condition is when an activation impedance of an electrode of the energy source is 50% or less of the total impedance of the electrode.
In some embodiments, the transition condition is when an activation impedance of an electrode of the energy source is 20% or less of the total impedance of the electrode.
In some embodiments, the transition condition is when an activation impedance of an electrode of the energy source is 10% or less of the total impedance of the electrode.
In some embodiments, the charge pulses are at peak voltages greater than a cutoff voltage of the energy source.
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 otherwise or logically implausible.
Processing circuitry can include one or more processors, microprocessors, controllers, and/or microcontrollers, each of which can be a discrete chip or distributed amongst (and a portion of) a number of different chips. 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 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.
Memory 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 be a separate chip of its own. Memory is non-transitory, and can be volatile (e.g., RAM, etc.) and/or non-volatile memory (e.g., ROM, flash memory, F-RAM, etc.).
Computer program instructions for carrying out operations in accordance with the described subject matter may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, JavaScript, Smalltalk, C++, C#, Transact-SQL, XML, PHP or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program instructions may execute entirely on the user's computing device (e.g., reader) or partly on the user's computing device. The program instructions may reside partly on the user's computing device and partly on a remote computing device or entirely on the remote computing device or server, e.g., for instances where the identified frequency is uploaded to the remote location for processing. In the latter scenario, the remote computing device may be connected to the user's computing device through any type of network, or the connection may be made to an external computer.
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.
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 later-developed variants thereof.
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. 63/084,352, filed Sep. 28, 2020, and U.S. Provisional Application No. 63/119,504, filed Nov. 30, 2020, both of which are incorporated by reference herein in their entireties and for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63119504 | Nov 2020 | US | |
| 63084352 | Sep 2020 | US |
