Electrochemical energy storage devices (e.g., batteries) comprising multiple cells, battery modules, or battery packs are used in many applications including, but not limited to, electric and hybrid vehicle applications, backup or emergency power systems, renewable energy systems, consumer electronics, and medical devices, amongst many others. Certain energy storage systems may implement active cell balancing circuits. However, such systems are rarely used due to their high complexity, large dimensions, large number of parts, and high costs. It is therefore desirable to provide energy storage systems with active cell balancing electronic circuits and control methods that are easy to implement, efficient, flexible, effective, have low number of parts/components and that are inexpensive.
Example systems, methods and apparatuses for providing voltage or state of charge (SOC) balancing and state-of-energy/power management and balancing are described herein.
Embodiments of the present disclosure provide active cell balancing electronic systems, components, and control methods. In some embodiments, two inductors, or a split inductor, and two switches, are used to balance four cells, modules, or packs. In some embodiments, only two inductors, or a split inductor, and only two switches, are used to balance four cells. In various examples, the components of the active cell balancing system (e.g., two switches and two inductors) are relatively small in size/volume and relatively inexpensive for the functionality it can realize. For example, the active cell balancing system may be configured to handle the current or processing of energy needed to balance a plurality of cells (or modules or packs) without handling the current or energy that is drawn from the plurality of cells by a load being powered by the plurality of cells. In some examples, a controller that allows for continued operation at the same or desired voltage level and balancing operation with any number of disconnected cells is provided. In some examples, a controller that allows for controlling the balancing current to achieve highest efficiency during cell balancing is provided. This can be accomplished, for example, by adjusting a value of the balancing current and/or the regulated or open circuit voltage.
In accordance with some embodiments of the present disclosure, an adaptive power system is provided. The adaptive power system can include a plurality of power sources; a state-of-charge (SOC) circuit including a plurality of switches and at least one inductor, wherein the plurality of switches includes first and second switches; and a controller operably coupled to plurality of switches, the controller being configured to operate the plurality of switches in a first mode and a second mode to balance a respective SOC of each of the plurality of power sources.
In some implementations, the plurality of power sources includes four power sources or less. Alternatively, the plurality of power sources includes three power sources or less. Alternatively, the plurality of power sources includes two power sources or less.
In some implementations, the system can further include at least one open circuit terminal that corresponds to a disconnected power source. Optionally, the controller is configured to compensate for the disconnected power source to operate the plurality of switches to generate a regulated voltage between the at least one open circuit terminal while balancing the respective SOC of each of the plurality of power sources.
Optionally, the plurality of power sources includes first, second, third, and fourth power sources. In some implementations, the first and second power sources are connected in series, the third and fourth power sources are connected in series, and the series-connected first and second power sources are connected in parallel with the series-connected third and fourth power sources.
In some implementations, the plurality of switches includes only the first and second switches.
In some implementations, the plurality of switches includes only two switches for each set of four power sources.
In some implementations, the first mode is a switching mode, the controller being configured to turn the plurality of switches ON and OFF in the switching mode. Optionally, the controller is configured to select a duty cycle for the switching mode, the duty cycle controlling an amount of charge transfer among the plurality of power sources. Optionally, the first mode is configured to balance the respective SOC of one or more vertically-connected power sources of the plurality of power sources.
In some implementations, the second mode is a non-switching mode, the controller being configured to maintain the plurality of switches OFF in the non-switching mode. Optionally, the second mode is configured to balance the respective SOC of one or more horizontally-connected power sources of the plurality of power sources.
In some implementations, the controller is further configured to monitor a respective voltage and/or SOC of each of the plurality of power sources. Optionally, the controller is further configured to alternate between the first and second modes responsive to the respective voltage and/or SOC of each of the plurality of power sources. Optionally, the controller is further configured to set a current value of the at least one inductor responsive to the respective voltage and/or SOC of each of the plurality of power sources. In some implementations, the controller is optionally further configured to set a current value of the at least one inductor to maximize efficiency and/or minimize power loss.
In some implementations, the at least one inductor is a center-tapped inductor or coupled inductors.
In some implementations, the at least one inductor is a plurality of inductors. Optionally, the plurality of inductors are first and second inductors. Optionally, the plurality of inductors share a magnetic core.
In some implementations, the SOC circuit further includes a first wiring for electrically connecting the plurality of switches to the plurality of power sources. In some implementations, the system further includes a load circuit including a second wiring and a load, the second wiring for electrically connecting the load to the plurality of power sources. Optionally, the first wiring is distinct from the second wiring. Optionally, the first wiring is configured to carry a SOC balancing current. Optionally, the second wiring is configured to carry a load current or a charging current.
In some implementations, the plurality of power sources are energy storage devices such as batteries. Optionally, each of the batteries is a battery cell or a battery pack.
In some implementations, the plurality of power sources are super/ultra capacitors, direct current (DC) micro grids, or photovoltaic (PV) cells.
In accordance with some embodiments of the present disclosure, another adaptive power system in described herein. The adaptive power system can include: a plurality of power sources, wherein the plurality of power sources includes four power sources or less; a state-of-charge (SOC) circuit consisting essentially of: two switches corresponding to the plurality of power sources, at least one inductor corresponding to the plurality of power sources, and a wiring for electrically connecting the two switches and the at least one inductor to the plurality of power sources; and a controller operably coupled to the two switches, the controller being configured to operate the two switches in a first mode and a second mode to balance a respective SOC of each of the plurality of power sources.
In accordance with some embodiments of the present disclosure, another adaptive power system in described herein. The adaptive power system can include: a plurality of power sources including a set of four power sources; a state-of-charge (SOC) circuit consisting essentially of: two switches corresponding to the set of four power sources, at least one inductor corresponding to the set of four power sources, and a wiring for electrically connecting the two switches and the at least one inductor to the set of four power sources; and a controller operably coupled to the two switches, the controller being configured to operate the two switches in a first mode and a second mode to balance a respective SOC of each of the set of four power sources.
In accordance with some embodiments of the present disclosure, another adaptive power system in described herein. The adaptive power system can include: a plurality of power sources; a state-of-charge (SOC) circuit including a plurality of switches and at least one inductor, wherein the plurality of switches includes first and second switches; and a controller operably coupled to plurality of switches, the controller being configured to operate the plurality of switches in a first mode and a second mode to balance a respective terminal or open circuit voltage of each of the plurality of power sources.
In accordance with some embodiments of the present disclosure, another adaptive power system in described herein. The adaptive power system can include: a plurality of power sources; at least one open circuit terminal that corresponds to a disconnected/not present power source; a state-of-charge (SOC) circuit including a plurality of switches and at least one inductor, wherein the plurality of switches includes first and second switches; and a controller operably coupled to plurality of switches, the controller being configured to compensate for the disconnected power source to operate the plurality of switches to generate a regulated voltage between the at least one open circuit terminal while balancing a respective SOC of each of the plurality of power sources.
In accordance with some embodiments of the present disclosure, another adaptive power system in described herein. The adaptive power system can include: a plurality of power sources; a state-of-charge (SOC) circuit including a plurality of switches and at least one inductor, wherein the plurality of switches includes first and second switches; and a controller operably coupled to plurality of switches, the controller being configured to operate the plurality of switches in a first mode and a second mode to maximize efficiency and/or minimize power loss.
Other systems, methods, features and/or advantages will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features and/or advantages be included within this description and be protected by the accompanying claims.
The components in the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding parts throughout the several views.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure. As used in the specification, and in the appended claims, the singular forms “a,” “an,” “the” include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. The terms “optional” or “optionally” used herein mean that the subsequently described feature, event or circumstance may or may not occur, and that the description includes instances where said feature, event or circumstance occurs and instances where it does not. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, an aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. While implementations will be described for a battery, it will become evident to those skilled in the art that the implementations are not limited thereto, but are applicable for other energy storage devices such as a supercapacitor or another type of electrochemical device or semiconductor device, among others.
Systems and methods for balancing SOC or state-of-energy of a plurality of power sources are described herein. It is important to balance SOC or state-of-energy, particularly during charging and discharging operations, to avoid or minimize risks of overcharging/discharging, damage, destruction, or fire. In implementations described herein, the SOC or state-of-energy balancing schemes are active, i.e., energy is transferred between power sources in the system. Optionally, in some implementations, energy is transferred to the load or from another source, which in addition to energy transfer between power sources. This is in contrast to passive schemes where energy is merely dissipated via resistors. An example power source is an energy storage device such as a battery or other electrochemical device or non-electrochemical device (e.g., supercapacitor or solar cell). A battery may refer to a battery cell or a plurality of battery cells (e.g., a battery pack or a battery module). As used herein, state-of-energy (or power) is a measure of how much energy (or power) is available or can be drawn from the source (or supplied/taken by one or more loads). For example, the amount of energy that is available from a solar panel under given irradiance level, from a battery, from a capacitor, or from a power grid, among others. Balancing can be for state of charge, state of energy, voltages, a currents, or for the amount of energy or power drawn from a source or consumed by a load. Additionally, balancing can be to make the above quantities equal, or it can be to make their values non-equal to predetermined values (for example, one value is double of the other value). As used herein, the term state of charge (SOC) refers to a measure of the level of charge of an energy storage device. SOC can be expressed as a ratio of the current level of charge of the energy storage device to its capacity. In some implementations, SOC may be estimated by measuring voltage of the energy storage device. It should be understood that energy storage devices are provided only as example power sources. This disclosure contemplates that the systems and methods described herein may be used with other power sources, which may include, but are not limited to, a supercapacitor, an ultracapacitor, a direct current (DC) microgrid (to balance state-of-power, energy, voltage, or current), or a photovoltaic (PV) cell to balance state-of-power, energy, voltage, or current).
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As described herein, the system 100 of
The system described herein can operate with one, two, three, or four batteries present out of the four batteries (i.e., can operate with any number of cells) as described in more detail herein. For example,
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As illustrated, in Mode 12, switches SA and SB are switching and are complementary (or optionally share a common OFF time) to balance Battery X1 and Battery X2, and/or Battery Y1 and Battery Y2, and/or to maintain balance SOC or voltages between X1, X2, Y1, and Y2. The amount of charge transferred between the batteries is a function of the duty cycle (the ratio between the ON time and the switching period). Mode 12 is also referred to herein as the switching mode. As further illustrated, in Mode XY, switches SA and SB are OFF and therefore not switching to balance the SOC between X1 and Y1 and between X2 and Y2. When switches SA and SB are OFF, X1 and Y1 become connected in parallel and X2 and Y2 become connected in parallel due to the existence of the inductor(s) which act as a wire/short circuit connecting the middle point between X1 and X2 to the middle point between Y1 and Y2. Mode XY is also referred to herein as the non-switching mode.
The controller can alternate between Mode 12 and Mode XY such that the desired SOC or voltage balancing is achieved. Mode 12 transfers charge vertically, i.e., between vertically-connected batteries. Mode 12 therefore balances the SOC or voltage between vertically-connected Battery X1 and Battery X2 and/or between vertically-connected Battery Y1 and Battery Y2. Mode XY transfers charge horizontally, i.e., between horizontally-connected batteries (in parallel when the switches are not switching). Mode XY therefore balances the SOC or voltage between horizontally-connected Battery X1 and Battery Y1 and/or between horizontally-connected Battery X2 and Battery Y2. Alternating between Mode 12 and Mode XY effectively allows this system to transfer charges between all four batteries using the two switches and the inductor(s).
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If ΔVm+1,m is larger than the voltage difference threshold value ΔVTh, the inductor current is commanded by the controller to be positive by setting the value of μ to +1 in order to transfer charge from Battery “m+1” to Battery “m.” If ΔVm+1,m is smaller than −ΔVTh, the inductor current is commanded by the controller to be negative by setting the value of μ to −1 in order to transfer charge from Battery “m” to Battery “m+1.” If the voltage difference is between −ΔVTh and ΔVTh, the value of μ is maintained at its current value until the voltage difference reaches one of the other limits (ΔVTh or −ΔVTh).
While the switches (see SA, SB) can be kept operating all the time, the switches can optionally be disabled once the balanced condition is reached in order to save some power loss. This ensures that the SOC circuit is only active when there is a voltage or SOC imbalance in the system. The balanced condition is reached when all voltage differences between all battery cells in the battery pack are between −ΔVTh and ΔVTh at the same time. The enable/disable logic 810A is shown in the top portion of
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While the switches (see SA, SB) can be kept operating all the time, the switches can optionally be disabled once the balanced condition is reached in order to save some power loss. This ensures that the SOC circuit is only active when there is a voltage or SOC imbalance in the system. The balanced condition is reached when all voltage differences or SOC differences between all battery cells in the battery pack satisfy the condition |V1−V2|<ΔVsmall or |SOC1−VOC2|<ΔSOCsmall. The enable/disable logic 810B is shown in
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In some embodiments, one or more of the batteries (or any device, system, or network that can source and sink power/current) can be a photovoltaic (PV) solar cell or panel such that it can charge the other batteries (or any device, system, or network that can source and sink power/current) and/or provide the energy needed for balancing operations. Example applications include any device, system, or equipment that requires energy storage to operate such as Electric and Hybrid Vehicles, backup or emergency power systems, renewable energy systems, consumer electronics, and medical systems, among many others. In some embodiments, the batteries can also be any device, system or network that can supply and source power/current. For example, each of the batteries shown in the diagrams could be replaced by a DC micro-grid or a supercapacitor/ultracapacitor.
In another embodiment, instead of balancing the terminal voltages of the batteries (V1 through Vm, or Vx1 through Vxm, or Vy1 through Vym, where m is the number of batteries), the controller can extract and balance the open circuit voltages (Voc1 through Vocm) of the battery cells (since they are more accurate representation of the SOC values). To balance open circuit voltages of battery cells, the voltage drop across the series resistance Rs of each battery cell needs to be compensated for.
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It should be appreciated that the logical operations described herein with respect to the various figures may be implemented (1) as a sequence of computer implemented acts or program modules (i.e., software) running on a computing device (e.g., the computing device described in
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In its most basic configuration, computing device 1500 typically includes at least one processing unit 1506 and system memory 1504. Depending on the exact configuration and type of computing device, system memory 1504 may be volatile (such as random access memory (RAM)), non-volatile (such as read-only memory (ROM), flash memory, etc.), or some combination of the two. This most basic configuration is illustrated in
Computing device 1500 may have additional features/functionality. For example, computing device 1500 may include additional storage such as removable storage 1508 and non-removable storage 1510 including, but not limited to, magnetic or optical disks or tapes. Computing device 1500 may also contain network connection(s) 1516 that allow the device to communicate with other devices. Computing device 1500 may also have input device(s) 1514 such as a keyboard, mouse, touch screen, etc. Output device(s) 1512 such as a display, speakers, printer, etc. may also be included. The additional devices may be connected to the bus in order to facilitate communication of data among the components of the computing device 1500. All these devices are well known in the art and need not be discussed at length here.
The processing unit 1506 may be configured to execute program code encoded in tangible, computer-readable media. Tangible, computer-readable media refers to any media that is capable of providing data that causes the computing device 1500 (i.e., a machine) to operate in a particular fashion. Various computer-readable media may be utilized to provide instructions to the processing unit 1506 for execution. Example tangible, computer-readable media may include, but is not limited to, volatile media, non-volatile media, removable media and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. System memory 1504, removable storage 1508, and non-removable storage 1510 are all examples of tangible, computer storage media. Example tangible, computer-readable recording media include, but are not limited to, an integrated circuit (e.g., field-programmable gate array or application-specific IC), a hard disk, an optical disk, a magneto-optical disk, a floppy disk, a magnetic tape, a holographic storage medium, a solid-state device, RAM, ROM, electrically erasable program read-only memory (EEPROM), flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices.
In an example implementation, the processing unit 1506 may execute program code stored in the system memory 1504. For example, the bus may carry data to the system memory 1504, from which the processing unit 1506 receives and executes instructions. The data received by the system memory 1504 may optionally be stored on the removable storage 1508 or the non-removable storage 1510 before or after execution by the processing unit 1506.
It should be understood that the various techniques described herein may be implemented in connection with hardware or software or, where appropriate, with a combination thereof. Thus, the methods and apparatuses of the presently disclosed subject matter, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computing device, the machine becomes an apparatus for practicing the presently disclosed subject matter. In the case of program code execution on programmable computers, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. One or more programs may implement or utilize the processes described in connection with the presently disclosed subject matter, e.g., through the use of an application programming interface (API), reusable controls, or the like. Such programs may be implemented in a high-level procedural or object-oriented programming language to communicate with a computer system. However, the program(s) can be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language and it may be combined with hardware implementations.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
This application claims the benefit of U.S. provisional patent application No. 63/420,832, filed on Oct. 31, 2022, and titled “ADAPTIVE POWER SYSTEMS AND CONTROL METHODS WITH STATE-OF-CHARGE OR STATE-OF-ENERGY/POWER BALANCING,” the disclosure of which is expressly incorporated herein by reference in its entirety.
Number | Date | Country | |
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63420832 | Oct 2022 | US |