Battery imbalance diagnosis based on reference electrode

Abstract

Techniques for battery imbalance diagnosis based on reference electrodes are provided. In an embodiment, the technique includes determining a state of health of a battery cell pack, determining a state of health of a battery cell in the battery cell pack, determining a battery cell imbalance of the battery cell pack based on a comparison of the state of health of the battery cell pack and the state of health of the battery cell, and generating an alarm signal or a control signal based on the battery cell imbalance.

Description

Technical Field

[0001] The present invention relates to battery cells, and more particularly, to detecting unbalanced degradation of individual battery cells in a battery pack. Background Art

[0002] Conventional battery packs typically include individual cells that degrade at different rates. Despite the degradation of some individual cells, the battery pack can still provide energy to the load. However, using a battery pack containing degraded cells can reduce performance and reliability. Summary of the invention

[0003] In an exemplary embodiment, a method for diagnosing and mitigating battery imbalance is provided. The method includes determining a state of health of a battery cell group; determining a state of health of a battery cell in the battery cell group; determining a battery cell imbalance of the battery cell group based on a comparison of the state of health of the battery cell group and the state of health of the battery cell; and generating an alarm signal or a control signal based on the battery cell imbalance.

[0004] In addition to one or more features described herein, determining a state of health of the battery cell group includes measuring a first set of voltages between cathodes and anodes of a plurality of battery cells in the battery cell group and comparing changes in the first set of voltages to changes in a state of charge of the battery cell group.

[0005] In addition to one or more features described herein, determining the state of health of a battery cell includes: discharging the battery cell group to a target state of charge range based on an expected failure cause of the battery cell group; measuring a second group of voltages of battery cells in the battery cell group within the target state of charge range when it is determined that an initial diagnostic condition is met; determining a metric of the second group of voltages; and determining the state of health of the battery cell based on the metric.

[0006] In addition to one or more features described herein, the initial diagnostic condition includes (i) a voltage change of the battery cell group below a voltage threshold, or (ii) a current of the battery cell group below a current threshold.

[0007] In addition to one or more features described herein, the second set of voltages includes a potential difference across the battery cell group, a potential difference between a reference electrode and a cathode of a battery cell, or a potential difference between a reference electrode and an anode of a battery cell.

[0008] In addition to one or more features described herein, the metrics include statistical variance and mean of voltages corresponding to state of health data points for various battery cell cycles.

[0009] In addition to one or more features described herein, determining a state of health of the battery cell includes using the metric as an index into a predetermined state of health table, and wherein the state of health table includes a mapping between the metric, battery cell cycles, and state of health values.

[0010] In another exemplary embodiment, a system is provided to diagnose and mitigate battery imbalance. The system includes a battery cell group, a processor, and a memory or storage device including an algorithm or computer instructions, which when executed by the processor performs operations including: determining a state of health of the battery cell group; determining a state of health of the battery cells in the battery cell group; determining a battery cell imbalance of the battery cell group based on a comparison of the state of health of the battery cell group and the state of health of the battery cells; and generating an alarm signal or a control signal based on the battery cell imbalance.

[0011] In addition to one or more features described herein, determining a state of health of the battery cell group includes measuring a first set of voltages between cathodes and anodes of a plurality of battery cells in the battery cell group and comparing changes in the first set of voltages to changes in a state of charge of the battery cell group.

[0012] In addition to one or more features described herein, determining the state of health of a battery cell includes: discharging the battery cell group to a target state of charge range based on an expected failure cause of the battery cell group; measuring a second group of voltages of battery cells in the battery cell group within the target state of charge range when it is determined that an initial diagnostic condition is met; determining a metric of the second group of voltages; and determining the state of health of the battery cell based on the metric.

[0013] In addition to one or more features described herein, the initial diagnostic condition includes (i) a voltage change of the battery cell group below a voltage threshold, or (ii) a current of the battery cell group below a current threshold.

[0014] In addition to one or more features described herein, the second set of voltages includes a potential difference across the battery cell group, a potential difference between a reference electrode and a cathode of a battery cell, or a potential difference between a reference electrode and an anode of a battery cell.

[0015] In addition to one or more features described herein, the metrics include statistical variance and mean of voltages corresponding to state of health data points for various battery cell cycles.

[0016] In addition to one or more features described herein, determining a state of health of the battery cell includes using the metric as an index into a predetermined state of health table, and wherein the state of health table includes a mapping between the metric, battery cell cycles, and state of health values.

[0017] In yet another exemplary embodiment, a computer-readable storage medium having computer-readable program code embodied therein is provided for diagnosing and mitigating battery imbalance. The computer-readable program code is executable by one or more computer processors to perform operations including: determining a state of health of a battery cell group; determining a state of health of a battery cell in the battery cell group; determining a battery cell imbalance of the battery cell group based on a comparison of the state of health of the battery cell group and the state of health of the battery cells; and generating an alarm signal or a control signal based on the battery cell imbalance.

[0018] In addition to one or more features described herein, determining a state of health of the battery cell group includes measuring a first set of voltages between cathodes and anodes of a plurality of battery cells in the battery cell group and comparing changes in the first set of voltages to changes in a state of charge of the battery cell group.

[0019] In addition to one or more features described herein, determining the state of health of a battery cell includes: discharging the battery cell group to a target state of charge range based on an expected failure cause of the battery cell group; measuring a second group of voltages of battery cells in the battery cell group within the target state of charge range when it is determined that an initial diagnostic condition is met; determining a metric of the second group of voltages; and determining the state of health of the battery cell based on the metric.

[0020] In addition to one or more features described herein, the initial diagnostic condition includes (i) a voltage change of the battery cell group below a voltage threshold, or (ii) a current of the battery cell group below a current threshold.

[0021] In addition to one or more features described herein, the second set of voltages includes a potential difference across the battery cell group, a potential difference between a reference electrode and a cathode of a battery cell, or a potential difference between a reference electrode and an anode of a battery cell.

[0022] In addition to one or more features described herein, the metric includes a statistical variance and mean of voltages corresponding to state of health data points for various battery cell cycles, and determining the state of health of the battery cell includes using the metric as an index into a predetermined state of health table, and wherein the state of health table includes a mapping between the metric, the battery cell cycles, and the state of health values.

[0023] The above features and advantages and other features and advantages of the present disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, advantages and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0025] Figure 1A vehicle according to an embodiment is shown;

[0026] Figure 2 A battery cell group diagnostic environment according to one embodiment is shown;

[0027] Figure 3 shows a computing environment according to an embodiment;

[0028] Figure 4 A flow chart showing a method of determining a state of health of a battery cell including a reference electrode according to an embodiment; and

[0029] Figure 5 A flow chart of a method of diagnosing an imbalance in a battery cell group according to an embodiment is shown. DETAILED DESCRIPTION

[0030] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or use. It should be understood that in all figures, corresponding reference numerals represent the same or corresponding parts and features. As used herein, the term "module" refers to one or more algorithms, instruction sets, software applications or other computer-readable program codes that can be executed by a processor to perform the functions, operations or processes described herein.

[0031] Embodiments of the present disclosure improve battery cell diagnostic systems by providing a reference electrode and a diagnostic module configured to diagnose battery degradation (e.g., increased internal impedance due to aging) of a battery cell in a battery cell group. The diagnostic module can determine the degradation based on the health state of the battery cell group and the health state of the battery cells in the battery cell group. In one embodiment, the diagnostic module determines the health state of the battery cell through a reference electrode inserted into the battery cell.

[0032] One benefit of the disclosed embodiments is reducing safety risks by diagnosing degradation of individual batteries in a battery cell group and generating alarms or control signals that can be used to mitigate usage of the degraded battery cells.

[0033] Figure 1 A vehicle 100 is shown according to one embodiment. The vehicle 100 includes a body 102 that may support a powertrain 104, a propulsion system 110, a controller 130, and other systems of the vehicle 100 described herein.

[0034] In one embodiment, the vehicle 100 is an electric vehicle (EV) or a hybrid electric vehicle (HEV). In the illustrated embodiment, the vehicle 100 is a HEV that is partially powered by a power system 104, which includes a plurality of interconnected battery cells. The power system 104 can be electrically coupled to at least one electric motor assembly of a propulsion system 110. In one embodiment, the power system 104 is electrically coupled to a direct current (DC) converter module 106 (e.g., a DC-DC converter) and an inverter module 108 (e.g., a traction power inverter unit). The inverter module 108 can include a plurality of inverters that convert a DC signal from the power system 104 into a three-phase alternating current (AC) signal to drive the electric motor of the propulsion system 110. The power system 104 can also be electrically coupled to vehicle electronic systems, such as an audio system, a display system, a navigation system, a temperature control system, etc.

[0035] The propulsion system 110 may include an internal combustion engine (ICE) system 112 and at least one electric motor assembly (e.g., a first electric motor 114 and a second electric motor 116). Each component of the propulsion system 110 may be configured to drive at least one wheel 120 of the vehicle 100 via a drivetrain coupled to a front axle or a rear axle coupled to a respective set of front and rear wheels 120.

[0036] In one embodiment, the controller 130 is configured to diagnose the power system 104 and control the propulsion system 110 or other systems of the vehicle 100. The controller 130 Figure 2 and Figure 3 Techniques for diagnosing the powertrain system 104 are discussed in greater detail in Figure 4 and Figure 5 discussed in.

[0037] Figure 2 A battery cell group diagnostic environment 200 is shown according to one embodiment. In the illustrated embodiment, the battery cell group diagnostic environment 200 includes a battery cell group (battery cell 202 1-N ), anode connection 208 1-N , Reference electrode connection 216 1-N 、Cathode connection 222 1-N and controller 130. In one embodiment, battery cell 202 1-N It is a lithium-ion battery cell.

[0038] like Figure 2 As shown, the battery cell 202 1 The battery cell 202 may include an anode 204, an anode tab 206, a separator 210, a current collector (not shown), a reference electrode 212, a reference electrode tab 214, a cathode 218, and a cathode tab 220. 1-NSimilar components and operations may be included.

[0039] In one embodiment, the anode 204 is a 1 The cathode 218 is a lower potential terminal of the battery cell 202 including a carbon graphite layer storing lithium atoms. 1 The higher potential terminal includes lithium metal oxide.

[0040] When there is an available path for electrons to move to cathode 218, the potential difference between anode 204 and cathode 218 causes the electrons to separate from the lithium atoms of anode 204 and move along the available path to cathode 218. For example, electrons can move from anode 204 to controller 130 (via first current collector, anode tab 206, and anode connection 208). 1 ), and then moves from the controller 130 to the cathode 218 (via the cathode connection 222 1 , cathode terminal tab 220 and a second current collector).

[0041] The separator 210 may include a semi-permeable insulator that is not conductive and an electrolyte material or solution that allows lithium ions to pass through while blocking electrons. In one embodiment, solvent molecules in the electrolyte combine with lithium ions that pass through the separator 210 and form a solid electrolyte interface (SEI) at the anode 204. The SEI prevents direct contact between the electrolyte and the electrons, thereby preventing the electrons from degrading the electrolyte. In this way, the separator 210 allows lithium ions to move between the anode 204 and the cathode 218 to neutralize the accumulation of electrons at the cathode 218.

[0042] In the illustrated embodiment, each battery cell 202 1-N In one embodiment, the reference electrode 212 is inserted into the battery cell 202 at the separator 210. 1 The reference electrode 212 may or may not contact components of the separator 210 and does not interfere with the function or operation of the separator 210. In addition, the potential of the reference electrode 212 is independent of the potential changes of the anode 204 and the cathode 218. For example, when the battery cell 202 1 When charged, the potentials of anode 204 and cathode 218 may change while the potential of reference electrode 212 remains constant.

[0043] The controller 130 may be configured to measure the voltage of the battery cell 202 via the anode tab 206 , the reference electrode tab 214 , and the cathode tab 220 . 1 As used herein, the battery cell 202 1The potential difference between the anode 204 and the cathode 218 may be referred to as V Cell1 Battery cell 202 2-N The corresponding potential differences can be referred to as V Cell2 To V CellN In general, the battery cell group (i.e., the battery cell 202 1-N ) can be called V CG .

[0044] The potential difference between the reference electrode 212 and the anode 204 may be referred to as V RA1 The potential difference between cathode 218 and reference electrode 212 may be referred to as V RC1 The term "reference electrode voltage" or V R1 Can be used for reference V RA1 or V RC1 Battery cell 202 2-N The corresponding reference electrode voltages can be referred to as V R2 To V RN .

[0045] In one embodiment, the controller 130 diagnoses the battery cells 202 in the battery cell group. 1-N The imbalance degradation. Figure 3 Controller 130 is further described in .

[0046] The controller 130 can be based on the V CG and V R1-RN The technique for determining the state of health of a battery cell including a reference electrode is as follows: Figure 4 Further described in .

[0047] For identifying battery cell 202 1-N The technique of unbalancing in may depend on the number of reference electrodes included in the battery cell group. Figure 5 Techniques for identifying imbalances are further described in .

[0048] Figure 3 FIG. 3 shows a computing environment 300 according to an embodiment. In the embodiment shown, the computing environment 300 includes a controller 130, a network 330, and a unit 202. 1-N .

[0049] In one embodiment, the controller 130 includes a processor 302, which obtains instructions and data from a memory 304 or a storage device 308 via a bus 322. Not all components of the controller 130 are shown. The controller 130 is typically under the control of an operating system (OS) suitable for performing or supporting the functions or processes disclosed herein. The processor 302 is a programmable logic device that performs instructions, logic, and mathematical processing, and may represent one or more CPUs. The processor may execute one or more algorithms, instruction sets, or applications in the memory 304 or the storage device 308 to perform the functions or processes described herein.

[0050] Memory 304 and storage 308 may represent hard drives, solid-state drives, flash memory devices, optical media, etc. Storage 308 may also include structured storage (e.g., databases). In addition, memory 304 and storage 308 may be considered to include storage physically located elsewhere. For example, memory 304 and storage 308 may be physically located on another computer that is communicatively coupled to controller 130 via bus 322 or network 330.

[0051] The controller 130 can be connected to other computers (eg, controllers, distributed databases, servers, or network hosts) or the battery unit 202 via the network interface 320 and the network 330. 1-N . The network 330 may include, for example, any combination of a bus, a physical transmission cable, an optical transmission fiber, or wireless transmission. In one embodiment, the network 330 includes a router, a firewall, a switch, a gateway computer, an edge server, a local area network, a wide area network, or a wireless network. The network may also include a vehicle controller area network (CAN) or a transmission control protocol (TCP) bus. The network interface 320 may be any type of network communication device that allows the controller 130 to communicate with other components of the computer and computing environment 300 via the network 330.

[0052] In the illustrated embodiment, the memory 304 includes a diagnostic module 306. In one embodiment, the diagnostic module 306 represents one or more algorithms, sets of instructions, software applications, or other computer readable program codes that are executable by the processor 302 to perform the functions, operations, or processes described herein.

[0053] In one embodiment, the diagnostic module 306 measures the battery cell (eg, V Cell1-N and V R1-N) and stores the voltage as battery cell data 312 in storage device 308. Diagnostic module 306 may also determine a metric based on the voltage and use the metric to estimate the state of health. The metric may be stored as battery cell data 312. The state of health may be stored in storage device 308 as state of health data 310. Diagnostic module 306 may then use state of health data 310 to determine a battery cell imbalance in the battery cell group. The operation of diagnostic module 306 is described herein. Figure 4-5 Detailed description is given in further detail in .

[0054] Figure 4 A flow chart of a method 400 of determining a state of health of a battery including a reference electrode is shown according to an embodiment. The method 400 begins at block 402 .

[0055] At block 404, the diagnostic module 306 discharges the battery cell group to a target state of charge (SOC) range. The target SOC range may be determined based on expected fault causes that increase the impedance of the battery cell group. Examples of fault causes may include cell plating degradation, electrolyte degradation, solid electrolyte interface (SEI) growth, separator degradation, etc.

[0056] Each fault cause may have a different detectability within different target SOC ranges. In addition, the potentials at the anode 204, reference electrode 212, and cathode 218 may each have different sensitivities to different fault causes. Therefore, a target SOC range may be selected based on the expected fault cause, and the battery cell group may be discharged to the target SOC range to provide a clear distinction between the potentials measured at the anode 204, reference electrode 212, or cathode 218 at different cycle counts. The potential at the anode 204, reference electrode 212, or cathode 218 may indicate the impedance of the battery cell group.

[0057] For example, as described above, solvent molecules in the electrolyte may combine with lithium ions and form SEI growth at the anode 204. SEI growth at the anode 204 may be an indicator of battery degradation. In one embodiment, the SEI may change the composition of the anode 204 so that the potential of the anode 204 at different cycles deviates at a low SOC range (e.g., 0.4V-0.6V) within a target voltage range (e.g., 2.5V-3V). Therefore, the method 400 may measure the voltage at the target SOC range to improve the battery cell 202 of the battery cell group. 1-N Diagnosis of degeneration.

[0058] At block 406, the diagnostic module 306 determines whether an initial diagnostic condition is satisfied. In one embodiment, the diagnostic condition includes at least one of: (i) a voltage change of the battery cell group below a voltage threshold, or (ii) a current of the battery cell group below a current threshold. The voltage threshold may represent a voltage value that ensures a stable voltage of the battery cell group (e.g., the voltage threshold may be on the order of 0.1V or less). The current threshold may represent a current value that ensures a small current or lack of current through the battery cell group (e.g., the threshold may be on the order of 0.1A or less).

[0059] When it is determined that the initial diagnostic conditions are not met, the method 400 proceeds to block 404 where the method 400 is performed as described above. However, when it is determined that the initial diagnostic conditions are met, the method 400 proceeds to block 408 .

[0060] At block 408, the diagnostic module 306 measures a set of voltages for each battery cell in the battery cell group under the target SOC range. In one embodiment, the set of voltages includes a potential difference (e.g., V Cell1-N , collectively referred to as V CG ), and the potential difference between the reference electrode and the anode or cathode of each battery cell (e.g., V RA1-N or V RC1-N , collectively referred to as V R1-N ).

[0061] At block 410, the diagnostic module 306 determines a metric for the group of voltages. In one embodiment, the metric includes a statistical variance and a mean for the group of voltages. For example, the metric may include the variance of the battery cell 202. 1-N In multiple measurements of V Cell1-N or V R1-N The variance and mean of .

[0062] At block 412, the diagnostic module 306 determines a state of health (SOH) based on the metrics. In one embodiment, the SOH of a battery cell represents the remaining useful life of the battery cell (e.g., internal impedance value, expected number of remaining life cycles, remaining charge percentage, etc.) as a ratio of the current condition of the battery cell to an ideal condition of the battery cell.

[0063] The diagnostic module 306 may determine the SOH of each battery cell in the battery cell group by using the metric as an index into a predetermined SOH table that maps the metric to the battery cell 202. 1-N The progressive life cycle of each battery cell 202 1-N The SOH table can be created by a calibration process that records the SOH from the battery cell 202 1-NThe SOH table can be stored in the storage device 308 as health status data 310. In this way, the battery cell 202 can be determined. 1-N SOH, used to Figure 5 The method 400 ends at block 414 .

[0064] Figure 5 A flow chart of a method 500 of diagnosing an imbalance in a battery cell group is shown according to an embodiment. The method 500 begins at block 502 .

[0065] At block 504, the diagnostic module 306 determines the state of health of the battery cell group. As used herein, the SOH of the battery cell group may be referred to as the SOH CG .

[0066] In one embodiment, the diagnostic module 306 measures the battery cell 202 1-N V between the cathode and anode Cell1-N And V Cell1-N The change in SOC is compared with the change in SOC of the battery cell group to determine the SOH CG When the battery cell 202 1-N This process may be performed when at least one of the battery cells 202 includes a reference electrode. 1-N When a reference electrode is included, the diagnostic module 306 uses a method similar to Figure 4 The process discussed in Determining SOH CG , the process determines that each battery cell 202 1-N SOH (commonly referred to as SOH CG ).

[0067] At block 506, the diagnostic module 306 determines the health status of the battery cells in the battery cell group. In a first non-limiting example, when the battery cell group includes only one reference electrode (e.g., when the battery cell 202 1 The battery cell 202 includes a reference electrode. 2-N When no reference electrode is included), the diagnostic module 306 uses a method similar to Figure 4 The process discussed in the foregoing is used to determine the SOH of a battery cell having a reference electrode (battery cell 202 1 SOH C1 ).

[0068] In a second non-limiting example, when at least two battery cells (e.g., battery cell 202 1-2 ) includes a reference electrode, and at least one battery cell (e.g., battery cell 202 N) does not include a reference electrode, the diagnostic module 306 uses Figure 4 The SOH of the battery cell with the reference electrode (respectively, the battery cell 202) is determined by a process similar to the process discussed in 1 and battery unit 202 2 SOH C1 and SOH C2 ). The diagnostic module 306 can then CG The SOH of the cell without the reference electrode (e.g., cell 202) is determined by multiplying the number of cells in the cell group, subtracting the SOH of the cell with the reference electrode, and dividing the remainder by the number of cells without the reference electrode. 3-N SOH C3-CN ). The resulting SOH represents the SOH of the battery cell without the reference electrode.

[0069] For example, when there are three battery cells in the battery cell group (eg, battery cell 202 including the reference electrode 1-2 and a battery cell 202 not including a reference electrode N ), SOH CN It can be determined as follows: SOH CN =(3*SOH CG –SOH C1 –SOH C2 ) / 1. In another example, when there are 5 battery cells in the battery cell group (eg, the battery cell 202 including the reference electrode 1-3 and a unit 202 not including a reference electrode 4-N ), SOH C4 and SOH CN It can be determined as follows: SOH C4 =SOH CN =(5*SOH CG –SOH C1 –SOH C2 –SOH C3 ) / 2.

[0070] In a third non-limiting example, when all of the battery cells 2021-N include a reference electrode, the diagnostic module 306 uses a method similar to Figure 4 The process discussed in the foregoing is used to determine the SOH of a battery cell (battery cell 202 1-N SOH C1-CN ).

[0071] At block 508 , the diagnostic module 306 determines whether there is a cell imbalance in the battery cell group. In one embodiment, the cell imbalance indicates degradation of the battery cells in the battery cell group (eg, degraded components due to aging, extreme temperatures, rapid charging, thermal cycling, etc.).

[0072] Continuing with the first example of block 506 (when the battery cell group includes only one reference electrode), when the SOH of the battery cell group (SOH CG ) is not equal to the SOH of the cell with the reference electrode (SOH C1 ), the diagnostic module 306 determines that there is a battery cell imbalance in the battery cell group. An imbalance threshold (T I ) acts as a buffer to eliminate the impact of small changes in SOH on the diagnosis. In other words, the SOH of the battery cell with the reference electrode (SOH C1 ) is expected to reflect the SOH of the battery cell group (SOH CG ). That is, the expected SOH C1 and SOH CG have similar remaining useful lives. Therefore, when SOH CG –SOH C1 >T I When SOH is , there is a difference in the remaining useful life of the battery cell group and the individual battery cells. Therefore, the diagnostic module 306 can determine that at least one battery cell in the battery cell group is unbalanced. However, when SOH is CG –SOH C1 <T I , the diagnostic module 306 determines that there is no imbalance in the battery cell group.

[0073] In this example, the diagnostic module 306 can identify a battery cell (eg, battery cell 202) having a reference electrode. 1 ) when including cell imbalance. However, when other cells (e.g., cell 202 2-N ), the diagnostic module 306 may identify that a cell imbalance exists in the battery cell group without determining which cell includes the imbalance.

[0074] Continuing with the second example of block 506 (when at least two but not all of the cells in the battery cell group include a reference electrode), when the SOH (SOH CG ) exceeds the SOH (SOH) of any single battery in the battery cell group C1-CN ), the diagnostic module 306 determines that there is a battery cell imbalance in the battery cell group. An imbalance threshold (T I ) as a buffer to eliminate the impact of small changes in SOH on diagnosis. In other words, the SOH (SOH) of each battery cell is expected to C1-CN ) reflects the SOH of the battery cell group (SOH CG ). As mentioned earlier, SOH represents the remaining useful life of a battery cell. Therefore, when SOH CG– Any SOH C1-CN >T I When the remaining service life of the corresponding battery cell is greater than the given SOH CG Therefore, in this case, the diagnostic module 306 can determine that there is an imbalance in the battery cell group due to the corresponding battery cell. However, when the SOH CG – Any SOH C1-CN <T I , the diagnostic module 306 may determine that there is no imbalance in the battery cell group.

[0075] According to a third example, the process described in the second example can also be used to diagnose cell imbalance when all cells include a reference electrode.

[0076] When it is determined that there is no cell imbalance, the method 500 proceeds to block 504 where the method 500 determines the SOH as described above. CG However, upon determining that cell imbalance does exist, method 500 proceeds to block 510 .

[0077] At block 510 , the diagnostic module 306 generates an alarm signal or a control signal based on the cell imbalance.

[0078] In one embodiment, the diagnostic module 306 sends an alert signal to a user of the battery cell pack. For example, if the battery cell pack is used in a vehicle, the diagnostic module 306 can send an alert signal to a display of the vehicle. The display can then display a warning of a battery cell imbalance diagnosis to the user, as well as a warning of potential dangers associated with battery cell imbalance.

[0079] In one embodiment, the diagnostic module 306 transmits the control signal to another controller that controls the use of the battery cell group. For example, if the battery cell group is used in a device, the diagnostic module 306 can send a control signal to the controller, which can shut down the device to prevent further use of the battery cell group. In another example, the diagnostic module 306 can transmit the control signal to a battery management system that disconnects the single battery cell that includes the imbalance so that the battery cell group can be used without the contribution from the battery cell that includes the imbalance. The method ends at box 512.

[0080] The terms "one" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced items. The term "or" means "and / or", unless the context clearly indicates otherwise. References to "an aspect" throughout the specification mean that a particular element (e.g., feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in any suitable manner in various aspects.

[0081] When an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0082] Unless otherwise indicated herein, all test standards are the most recent standards in effect as of the filing date of the present application or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0083] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0084] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from the scope thereof. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the disclosure without departing from the essential scope of the disclosure. Therefore, it is intended that the disclosure is not limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A vehicle power control system, comprising: Battery cell group; processor; as well as A memory or storage device including an algorithm or computer instructions that, when executed by a processor, performs operations including: Determining the health status of a battery cell group; determining a state of health of battery cells in a battery cell group; determining a battery cell imbalance of the battery cell group based on a comparison of a health state of the battery cell group and a health state of the battery cell; as well as An alarm signal or a control signal is generated based on the battery cell imbalance.

2. The vehicle power control system according to claim 1, wherein: Determining the health status of the battery cell group includes: measuring a first set of voltages between cathodes and anodes of a plurality of battery cells in the battery cell group; and The change in the first group voltage is compared to the change in the state of charge of the battery cell group.

3. The vehicle power control system according to claim 1, wherein: Determining the health status of the battery cell includes: discharging the battery cell group to a target state of charge range; When it is determined that the initial diagnostic condition is satisfied, measuring a second group of voltages of battery cells in the battery cell group within a target state of charge range; determining a metric for a second set of voltages; and A state of health of the battery cell is determined based on the metric.

4. The vehicle power control system according to claim 3, wherein: The initial diagnostic condition includes: (i) a voltage change of the battery cell group that is below a voltage threshold, or (ii) a current of the battery cell group that is below a current threshold.

5. The vehicle power control system according to claim 3, wherein: The second set of voltages includes a potential difference across the battery cell group, a potential difference between a reference electrode and a cathode of the battery cell, or a potential difference between a reference electrode and an anode of the battery cell.

6. The vehicle power control system according to claim 3, wherein: The metrics include statistical variance and mean of voltages corresponding to state-of-health data points for various battery cell cycles.

7. The vehicle power control system according to claim 3, wherein: Determining the state of health of the battery cell includes using the metric as an index into a predetermined state of health table, and wherein the state of health table includes a mapping between the metric, battery cell cycles, and state of health values.

8. A computer-readable storage medium having computer-readable program code embodied therein, the computer-readable program code being executable by one or more computer processors to perform operations comprising: determining the health status of a battery cell group; determining a state of health of battery cells in a battery cell group; determining a battery cell imbalance of the battery cell group based on a comparison of the health status of the battery cell group and the health status of the battery cells; and An alarm signal or a control signal is generated based on the battery cell imbalance.

9. The computer-readable storage medium of claim 8, wherein: Determining the health status of the battery cell group includes: measuring a first set of voltages between cathodes and anodes of a plurality of battery cells in the battery cell group; and The change in the first group voltage is compared to the change in the state of charge of the battery cell group.

10. The computer-readable storage medium of claim 8, wherein: Determining the health status of the battery cell includes: discharging the battery cell group to a target state of charge range; When it is determined that the initial diagnostic condition is satisfied, measuring a second group of voltages of battery cells in the battery cell group within a target state of charge range; determining a metric for a second set of voltages; and A state of health of the battery cell is determined based on the metric.

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