Method, system and device for determining full charge capacity and health status of battery pack

Abstract

The present invention relates to a method for determining the full charge capacity of a battery pack, including: obtaining a first state of charge value of a battery cell at a first state of charge correction moment; calculating a net cumulative charge amount from the first state of charge correction moment to the full charge moment; obtaining a voltage-capacity curve of a fully charged battery cell from the start of the end of charging to the full charge moment, and the fully charged battery cell reaches a first full charge voltage at the full charge moment; obtaining a second voltage of an undercharged battery cell at the full charge moment; based on the voltage-capacity curve and the second voltage, obtaining a capacity difference between the undercharged battery cell at the full charge moment and when it reaches the first full charge voltage; dividing the capacity difference by the actual full charge capacity to calculate a state of charge difference; subtracting the state of charge difference of the undercharged battery cell from the second state of charge value of the fully charged battery cell to calculate the second state of charge value of the undercharged battery cell at the full charge moment; obtaining a state of charge change amount; calculating the full charge capacity; and obtaining the full charge capacity of the battery pack according to the calculated full charge capacity.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly relates to a method for determining the full charge capacity of a battery pack, a method for determining the health status of a battery pack, a battery management system, and an electrical device. Background Art

[0002] In the field of batteries, the full charge capacity (FCC) is usually used as the standard capacity to indicate the accurate remaining capacity of the battery. In this case, the remaining capacity represents the relative state of charge (RSOC) as a percentage of the full charge capacity. The full charge capacity represents the maximum rechargeable capacity of the battery, and it will show a certain attenuation during the operation of the battery, which is mainly related to the usage time of the battery, the number of charge and discharge cycles, the operating conditions, and the ambient temperature. Therefore, during the use of the battery, it is necessary to correct the full charge capacity of the battery.

[0003] Currently, the full charge capacity of the battery is often obtained by dividing the change in the charge and discharge power by the change in the state of charge (SOC) of the battery. However, the accuracy of the real-time estimated SOC is not enough, so it is necessary to use the static open circuit voltage (OCV) of the battery to determine the accurate SOC according to the OCV-SOC curve after the battery is static. Summary of the Invention

[0004] The present application realizes that in order to obtain an accurate full charge capacity currently, it is necessary to obtain two relatively accurate SOCs at least at two SOC correction times to obtain the change in SOC to estimate the full charge capacity of the battery. On the one hand, for some types of batteries (for example, lithium iron phosphate batteries), there is a wide plateau region in the open circuit voltage-state of charge curve of the battery and the SOC cannot be corrected according to the OCV-SOC curve in the plateau region, so the opportunity to correct the SOC is less. On the other hand, in a battery pack, there are individual differences between batteries. When one battery is in the opportunity to correct the SOC, another battery may be in the plateau region of the OCV-SOC curve, so the full charge capacity of all batteries cannot be estimated. Therefore, the opportunity to update the full charge capacity of the battery pack is less.

[0005] In view of the above deficiencies in the prior art, the purpose of the present application is to provide a method for determining the full charge capacity of a battery pack, a method for determining the State Of Health (SOH) of a battery pack, a Battery Management System (BMS), and an electrical device, so as to provide more opportunities to correct the full charge capacity of the battery pack and improve the accuracy of the full charge capacity of the battery pack.

[0006] To achieve the above purpose, the first aspect of the present application provides a method for determining the full charge capacity of a battery pack, the method comprising:

[0007] Obtaining a first state of charge value of a battery cell in the battery pack at a first state of charge correction moment;

[0008] Calculating a net cumulative charge amount from the first state of charge correction moment to the full charge moment of the battery pack;

[0009] Obtaining a voltage-capacity curve of a fully charged battery cell from the starting moment at the end of charging to the full charge moment, where the fully charged battery cell is the battery cell in the battery pack that reaches a first full charge voltage at the full charge moment;

[0010] Obtaining a second voltage of an undercharged battery cell other than the fully charged battery cell in the battery pack at the full charge moment;

[0011] Based on the voltage-capacity curve and the second voltage of the undercharged battery cell, obtaining a capacity difference between the undercharged battery cell at the full charge moment and when the undercharged battery cell reaches the first full charge voltage;

[0012] Dividing the capacity difference of the undercharged battery cell by the actual full charge capacity of the undercharged battery cell to calculate a state of charge difference between the undercharged battery cell at the full charge moment and at the first full charge voltage;

[0013] Obtaining a second state of charge value of the fully charged battery cell at the full charge moment;

[0014] Subtracting the state of charge difference of the undercharged battery cell from the second state of charge value of the fully charged battery cell to calculate the second state of charge value of the undercharged battery cell at the full charge moment;

[0015] Obtaining the differences between the second state of charge values and the first state of charge values of the fully charged battery cell and the undercharged battery cell respectively as the state of charge change amounts of the fully charged battery cell and the undercharged battery cell;

[0016] Dividing the net cumulative charge amount by the state of charge change amount to calculate the full charge capacities of the fully charged battery cell and the undercharged battery cell; and

[0017] Obtain the full charge capacity of the battery pack based on the calculated full charge capacities of the fully charged cells and the undercharged cells.

[0018] In the above embodiments, in order to obtain a relatively accurate SOC, obtain the SOC at the state of charge correction moment. Specifically, correct the SOC of the battery at the first state of charge correction moment and obtain the relatively low first relatively accurate SOC of the battery.

[0019] In addition, in the above embodiments, by comparing the dynamic voltage curve shapes of each cell during the charging process, self-learn the voltage curve shape characteristics, so that all the cells in the battery pack can obtain another relatively accurate SOC that is relatively high and required for capacity estimation through the dynamic voltage. Therefore, it is not necessary to let the battery stand still twice to obtain the SOC differences of all the cells. In addition, for some cells in the OCV-SOC platform region, the SOC differences can also be calculated. Therefore, the SOC differences of all the cells can be calculated, and then the full charge capacities of all the cells can be estimated, and there are more opportunities to update the full charge capacity of the battery pack in the case of cell series connection.

[0020] In an embodiment of the present application, when the cells are connected in series with each other, the step of obtaining the full charge capacity of the battery pack includes: taking the minimum capacity among the calculated full charge capacities of the cells in the battery pack as the full charge capacity of the battery pack. Those skilled in the art should understand that this embodiment is a preferred embodiment when the cells are in series connection. When the cells are in different connection modes, the full charge capacity of the battery pack can be determined according to the calculated full charge capacities of the cells according to the specific connection mode.

[0021] If steps are stated in sequence in this specification or claims, this does not necessarily mean that the embodiments or aspects are limited to the stated sequence. On the contrary, it is conceivable that the steps can also be executed in a different sequence or in parallel with each other, unless one step is based on another step, and the step that absolutely needs to be established must be executed subsequently (however, this will become clear in individual cases). Therefore, the stated sequence can be a preferred embodiment.

[0022] In some embodiments, based on the static open circuit voltage-state of charge curve of the cells in the battery pack and the voltage when the battery pack meets the standing condition, obtain the static state of charge values of the cells in the battery pack. When the maximum value among the static state of charge values of the cells in the battery pack is lower than a preset state of charge threshold, the static state of charge value is the first state of charge value and the moment of obtaining the static state of charge value is the first state of charge correction moment.

[0023] In this embodiment, the SOC below the low-end SOC threshold is taken as the first corrected SOC of the battery cell, and by performing the correction only when the maximum SOC among all battery cells reaches the low-end SOC threshold, it is ensured that all battery cells are below the low-end SOC threshold. In some embodiments, the low-end SOC threshold is within the low SOC range with a relatively large slope in the OCV-SOC curve of the battery cell. In one embodiment, the low-end SOC threshold is 20%. By taking the SOC below the low-end SOC threshold as the first corrected SOC of the battery cell, the SOC difference of almost the full range is measured, so the accuracy of the full charge capacity obtained therefrom is relatively high.

[0024] In addition, in some embodiments, the static condition of the battery pack is that the current of the battery pack is less than the current threshold for a duration exceeding the time threshold, where the current threshold and the time threshold are obtained through actual tests. In actual tests, when the current is less than or equal to the current threshold, the voltage differences under the same SOC condition are within the allowable accuracy range. In one embodiment, the allowable accuracy range is 3 mV. In addition, in actual tests, when the current less than or equal to the current threshold lasts for a certain time, the voltage no longer changes significantly with time, and this time is the time threshold for meeting the static condition.

[0025] In some embodiments, the step of obtaining the capacity difference of the undercharged battery cell includes:

[0026] Substituting the second voltage of the undercharged battery cell into the voltage-capacity curve to obtain the remaining capacity value of the fully charged battery cell at the second voltage; and

[0027] Subtracting the remaining capacity value of the fully charged battery cell at the second voltage from the remaining capacity value of the fully charged battery cell at the first full charge voltage to obtain the capacity difference of the undercharged battery cell.

[0028] Since the voltage-capacity curves of each battery cell are approximately the same at the end of charging, the capacity difference between the undercharged battery cell at two voltages is approximately the same as the capacity difference between the fully charged battery cell at the same two voltages. Then, by dividing this capacity difference by the actual full charge capacity of the undercharged battery cell, the state of charge difference between the undercharged battery cell at the full charge moment (at this time, the voltage of the undercharged battery cell is lower than the first full charge voltage) and at the first full charge voltage can be calculated. As described above, the relatively accurate second state of charge of the undercharged battery cell can be calculated through this state of charge difference.

[0029] In some embodiments, the method includes updating the actual full charge capacity of the battery cell in the battery pack with the calculated full charge capacity of the battery cell.

[0030] In some embodiments, the battery cells in the battery pack meet the conditions at the end of charging when the voltage of the cell exceeds a preset voltage threshold. Judging whether it is at the end of charging through voltage is relatively simple and can save computing resources.

[0031] In other embodiments, the battery cells in the battery pack meet the conditions at the end of charging when the rate of change of the voltage of the cell over time or over the state of charge exceeds a preset voltage change rate threshold.

[0032] In some embodiments, the net cumulative charge is calculated according to the ampere-hour integration method.

[0033] In some embodiments, based on the corrected full charge capacity obtained by correcting the full charge capacity of the fully charged cell last time and according to the ampere-hour integration method, the real-time remaining capacity value of the fully charged cell is calculated in real time.

[0034] The second aspect of the present application provides a method for determining the health status of a battery pack, the method comprising:

[0035] Dividing the current full charge capacity of the battery pack determined by the method for determining the full charge capacity of the battery pack according to the first aspect above by the rated full charge capacity of the battery pack to obtain the health status of the battery pack.

[0036] The third aspect of the present application provides a battery management system, the battery management system comprising:

[0037] At least one processor; and

[0038] A memory connected to the at least one processor;

[0039] Wherein the memory stores instructions, when the instructions are executed by the at least one processor, the instructions cause the at least one processor to execute the method for determining the full charge capacity of the battery pack according to the first aspect above and / or the method for determining the health status of the battery pack according to the second aspect above.

[0040] The fourth aspect of the present application provides an electrical device, the electrical device comprising: a battery pack; and the battery management system according to the third aspect above. The battery can be used as the power source of the device or as the energy storage unit of the device. The device can be but is not limited to mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. The device can select the battery according to its usage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To more clearly illustrate the technical solutions of the present application, the accompanying drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the accompanying drawings described below are only some implementation solutions of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on the accompanying drawings.

[0042] Figure 1 The flowchart of a method for determining the full charge capacity of a battery pack according to an embodiment of the present application is illustrated;

[0043] Figure 2 The schematic diagram of the static OCV-SOC curve of a lithium iron phosphate battery according to an embodiment of the present application is illustrated;

[0044] Figure 3 The schematic diagram of the voltage-capacity curve for calculating the SOC difference at the full charge moment according to an embodiment of the present application is illustrated;

[0045] Figure 4 The flowchart of a method for determining the health status of a battery pack according to an embodiment of the present application is illustrated;

[0046] Figure 5 is a schematic diagram of a battery management system according to an embodiment of the present application; and

[0047] Figure 6 is a schematic diagram of an electrical device including a battery management system according to an embodiment of the present application. Detailed Description of Specific Embodiments

[0048] The embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0049] Figure 1 The flowchart of a method for determining the full charge capacity of a battery pack according to an embodiment of the present application is illustrated. As Figure 1 shown, in step 102, the first state of charge value of each battery cell in the battery pack at the first state of charge correction moment is obtained. In some embodiments of the present application, the first state of charge value of the battery cell is corrected in the low SOC region. When correcting the SOC according to the open circuit voltage method, it is required to correct in the section where the static OCV-SOC curve has a certain slope, because when the slope of the static OCV-SOC curve approaches zero, the same voltage may correspond to a relatively large SOC range, and the voltage sampling error or other voltage errors caused by other reasons may bring large SOC fluctuations. Therefore, the accuracy of the SOC obtained in this way is too low. Taking the lithium iron phosphate battery as an example, further referring to Figure 2, the static OCV-SOC curve of the lithium iron phosphate battery has two relatively wide plateau regions in the range of 30%-80%. As described above, the SOC cannot be corrected by the open circuit voltage method in the plateau region.

[0050] However, after the battery is discharged to a lower SOC, the slope of the OCV-SOC curve is no longer so gentle, and the SOC can be corrected by the open circuit voltage method. During charge and discharge, the flow of current through the battery causes the concentration of certain ions near the electrode to change due to the electrode reaction, and the rate of ion diffusion in the battery body solution cannot catch up to make up for this change, resulting in a concentration gradient of ions, that is, a concentration difference gradient between the solution near the electrode and the battery body solution, causing the electrode potential to deviate from the equilibrium electrode potential, resulting in the polarization of the battery; that is, overpotentials are generated at the positive and negative electrodes of the battery, causing the voltage of the battery to deviate from the actual voltage. By standing still, this concentration difference can be eliminated, and the electrode can be restored to the equilibrium potential.

[0051] Specifically, in some embodiments of the present application, when the current of the battery is less than the current threshold for more than the time threshold, the battery is completely depolarized and meets the standing condition; at this time, the static voltage value of each battery cell in the battery pack is obtained, and according to Figure 2 the OCV-SOC curve in, the SOC of each battery cell is determined. Only when the SOC of all battery cells is in the low-end region with a large slope in the OCV-SOC curve, the SOC of each battery cell is corrected according to the SOC obtained from the OCV-SOC curve. In one embodiment, the low-end SOC threshold of the low-end region with a large slope is 20%.

[0052] It should be understood that correcting the first state of charge value of the battery cells in the battery pack in the low-end SOC region is a preferred embodiment of the present application. Those skilled in the art can think of using the SOC value corrected by other SOC correction opportunities as the first state of charge value. For example, in some embodiments, the first state of charge correction moment can be selected in the region with a large slope between the two plateau regions in the OCV-SOC curve. In some embodiments, the first state of charge correction moment is selected in the region where the voltage change per 1% change in SOC exceeds 3 mV between the two plateau regions in the OCV-SOC curve.

[0053] In step 104, obtain the voltage-capacity curve of the fully charged cell from the starting moment at the end of charging to the full charge moment, where the fully charged cell is the cell in the battery pack that reaches the first full charge voltage at the full charge moment. In some embodiments, the first full charge voltage is a constant value obtained from offline calibration tests. Additionally, in some embodiments, based on the corrected full charge capacity obtained from the previous correction of the fully charged cell and according to the ampere-hour integration method, the real-time remaining capacity value of the fully charged cell is calculated in real time. By the calculated real-time remaining capacity value and the measured voltage, the voltage-capacity curve can be obtained, and such a voltage-capacity curve is as shown in Figure 3 the curve in. In some embodiments, each cell meets the condition at the end of charging when the voltage of the cell exceeds a preset voltage threshold. In other embodiments, each cell meets the condition at the end of charging when the rate of change of the voltage of the cell with respect to time or state of charge exceeds a preset voltage change rate threshold.

[0054] As Figure 3 shown, due to the individual differences between the cells, after the series-connected cells have accumulated the same amount of charge, their respective voltages are different. Figure 1 The method exemplified in is exactly using this characteristic of approximate waveform shape. In step 106, obtain the second voltage of the uncharged cells other than the fully charged cell in the battery pack at the full charge moment; in step 108, obtain the second state of charge value of the fully charged cell at the full charge moment; in step 110, calculate the net cumulative charge amount from the first state of charge correction moment to the full charge moment of the battery pack. Net cumulative charge amount = cumulative charge amount during charging - cumulative discharge amount during discharging; specifically, the net cumulative charge amount is calculated according to the ampere-hour integration method, that is, the cumulative charge amount during charging is the time integral of the charging current and the cumulative discharge amount during discharging is the time integral of the discharge current. Those skilled in the art should understand that steps 104-110 can be executed simultaneously or in different orders successively.

[0055] In step 112, substitute the second voltage of each uncharged cell into the voltage-capacity curve to obtain the capacity difference of each uncharged cell at the full charge moment and the capacity when the uncharged cell reaches the first full charge voltage. Specifically, referring again to Figure 3 , the solid line is the voltage-capacity curve of the fully charged cell at the end of charging, and the dotted line is the voltage-capacity curve of the uncharged cell at the end of charging. The shape characteristics of the two curves are similar. Therefore, by substituting the second voltage of the uncharged cell into the voltage-capacity curve, the remaining capacity value of the fully charged cell at the second voltage can be obtained, and by subtracting the remaining capacity value of the fully charged cell at the second voltage from the remaining capacity value of the fully charged cell at the first full charge voltage, the capacity difference of the fully charged cell can be obtained, and this capacity difference is almost equal to the corresponding capacity difference of the uncharged cell.

[0056] In step 114, for each undercharged cell, divide the capacity difference by the actual full charge capacity of the undercharged cell to calculate the state of charge difference of each undercharged cell at the full charge moment and at the first full charge voltage.

[0057] Subsequently, in step 116, subtract the state of charge difference of each undercharged cell from the second state of charge value of the fully charged cell to calculate the second state of charge value of each undercharged cell at the full charge moment.

[0058] In step 118, obtain the difference between the second state of charge value and the first state of charge value of each cell in the battery pack as the state of charge change amount of each cell.

[0059] In step 120, divide the net cumulative charge amount by the state of charge change amount of each cell to calculate the full charge capacity of each cell.

[0060] In the case of series-connected cells, in step 122, take the minimum capacity among the calculated full charge capacities of all cells in the battery pack as the full charge capacity of the battery pack.

[0061] Figure 1 The method exemplified utilizes the characteristic that the voltage-capacity curve shapes of each cell are approximately similar at the end of charging, enabling all cells in the battery pack to obtain the SOC change amount corresponding to the voltage difference between the dynamic voltage and the full charge voltage based on the dynamic voltage, thereby enabling the acquisition of another relatively accurate SOC, that is, the relatively large SOC required for estimating the full charge capacity. Therefore, on the one hand, it is not necessary to let the battery stand still twice to obtain the difference between two relatively accurate SOCs. On the other hand, for some cells in the OCV-SOC platform region, it is also possible to calculate the difference between two relatively accurate SOCs, and thus it is possible to calculate the difference between two relatively accurate SOCs of all cells, and further estimate the full charge capacity of all cells. In addition, in the case of series-connected cells, this method has more opportunities to update the full charge capacity of the battery pack.

[0062] In some embodiments, the method for determining the full charge capacity of a battery pack may further include: updating the actual full charge capacity of each cell with the calculated full charge capacity of each cell.

[0063] Figure 4 Illustrates a flowchart of a method for determining the health status of a battery pack according to an embodiment of the present application. As Figure 4 shown, in step 402, the current full charge capacity of the battery pack determined according to the method described in the reference Figure 1 Subsequently, in step 404, divide the current full charge capacity by the rated full charge capacity of the battery pack to obtain the health status of the battery pack.

[0064] Based on the same inventive concept, please refer to Figure 5 , in an embodiment of the present application, a battery management system 500 is further provided, including: at least one processor 501; and a memory 502 communicatively connected to the processor 501; wherein, the memory 502 stores instructions executable by the processor, and when the instructions are executed by the processor 501, the instructions cause the processor 501 to be capable of executing the method for correcting the state of charge of the battery provided by the embodiment of the present application.

[0065] Wherein, the processor 501 and the memory 502 are directly or indirectly electrically connected to realize data transmission or interaction. For example, these components can be electrically connected through one or more communication buses or signal buses. The method for correcting the state of charge of the battery respectively includes at least one software function module that can be stored in the memory 502 in the form of software or firmware.

[0066] The processor 501 can be an integrated circuit chip with signal processing capabilities. The processor 501 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor, an application-specific integrated circuit, a field-programmable gate array, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiment of the present application. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0067] The memory 502 can store various software programs and modules, such as the program instructions / modules corresponding to the method and device for correcting the state of charge of the battery provided by the embodiment of the present application. The processor 501 executes various functional applications and data processing by running the software programs and modules stored in the memory 502, that is, the method in the embodiment of the present application is realized.

[0068] The memory 502 can include but is not limited to a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc.

[0069] Each embodiment and specific example in the foregoing method for correcting the state of charge of a battery are equally applicable to Figure 5 the battery management system 500 shown. Through the detailed description of the foregoing method for correcting the state of charge of a battery, those skilled in the art can clearly know Figure 5 the implementation method of the battery management system 500 in, so for the sake of brevity of the specification, it will not be elaborated herein.

[0070] In addition, the present application also provides a device, which includes: a battery; and as Figure 5 shown in the battery management system. The battery can be used as the power source of the device or as the energy storage unit of the device. The device can be but is not limited to a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc. The device can select a battery according to its usage requirements.

[0071] Figure 6 is a device as an example. The device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. As another example of the device, it can be a mobile phone, a tablet computer, a laptop computer, etc.

[0072] Although the present invention has been described with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for determining the full charge capacity of a battery pack, the method comprising: Obtaining a first state of charge value of a battery cell in the battery pack at a first state of charge correction moment; Calculating a net cumulative charge amount from the first state of charge correction moment to the full charge moment of the battery pack; Obtaining a voltage-capacity curve of a fully charged battery cell between the starting moment at the end of charging and the full charge moment, where the fully charged battery cell is the battery cell in the battery pack that reaches a first full charge voltage at the full charge moment; Obtaining a second voltage of an undercharged battery cell other than the fully charged battery cell in the battery pack at the full charge moment; Based on the voltage-capacity curve and the second voltage of the undercharged battery cell, obtaining a capacity difference of the undercharged battery cell between the full charge moment and the moment when the undercharged battery cell reaches the first full charge voltage; Dividing the capacity difference of the undercharged battery cell by the actual full charge capacity of the undercharged battery cell to calculate a state of charge difference of the undercharged battery cell between the full charge moment and the moment at the first full charge voltage; Obtaining a second state of charge value of the fully charged battery cell at the full charge moment; Subtracting the state of charge difference of the undercharged battery cell from the second state of charge value of the fully charged battery cell to calculate a second state of charge value of the undercharged battery cell at the full charge moment; Obtaining a difference between the second state of charge value and the first state of charge value of the fully charged battery cell as a state of charge change amount of the fully charged battery cell; Obtaining a difference between the second state of charge value and the first state of charge value of the undercharged battery cell as a state of charge change amount of the undercharged battery cell; Dividing the net cumulative charge amount by the state of charge change amount of the fully charged battery cell and the state of charge change amount of the undercharged battery cell respectively to calculate the full charge capacity of the fully charged battery cell and the undercharged battery cell; And Obtaining the full charge capacity of the battery pack according to the calculated full charge capacities of the fully charged battery cell and the undercharged battery cell.

2. The method according to claim 1, wherein a static state of charge value of a battery cell in the battery pack is obtained based on a static open-circuit voltage-state of charge curve of the battery cell in the battery pack and a voltage when the battery pack meets a static condition, and when a maximum value among the static state of charge values of the battery cells in the battery pack is lower than a preset state of charge threshold, the static state of charge value is the first state of charge value and the moment of obtaining the static state of charge value is the first state of charge correction moment.

3. The method according to claim 1, wherein the step of obtaining the capacity difference of the undercharged battery cell comprises: Substituting the second voltage of the undercharged battery cell into the voltage-capacity curve to obtain a remaining capacity value of the fully charged battery cell at the second voltage; And Subtracting the remaining capacity value at the second voltage from the remaining capacity value of the fully charged battery cell at the first full charge voltage to obtain the capacity difference of the undercharged battery cell.

4. The method according to any one of claims 1 to 3, wherein the method comprises: Update the actual full charge capacity of the battery cell in the battery pack with the calculated full charge capacity of the battery cell in the battery pack.

5. The method according to any one of claims 1 to 3, wherein the battery cell in the battery pack satisfies the condition at the end of charging when the voltage of the battery cell exceeds a preset voltage threshold.

6. The method according to any one of claims 1 to 3, wherein the battery cell in the battery pack satisfies the condition at the end of charging when the rate of change of the voltage of the battery cell with respect to time or state of charge exceeds a preset voltage change rate threshold.

7. The method according to any one of claims 1 to 3, wherein the net cumulative charge amount is calculated according to the ampere-hour integration method.

8. The method according to any one of claims 1 to 3, wherein the real-time remaining capacity value of the fully charged battery cell is calculated in real time based on the corrected full charge capacity obtained by correcting the full charge capacity of the fully charged battery cell last time and according to the ampere-hour integration method.

9. A method for determining the health status of a battery pack, the method comprising: Dividing the current full charge capacity of the battery pack determined by the method for determining the full charge capacity of the battery pack according to any one of claims 1 to 8 by the rated full charge capacity of the battery pack to obtain the health status of the battery pack.

10. A battery management system, the battery management system comprising: At least one processor; And A memory connected to the at least one processor; Wherein the memory stores instructions that, when executed by the at least one processor, cause the at least one processor to execute the method for determining the full charge capacity of the battery pack according to one of claims 1-8 and / or the method for determining the health status of the battery pack according to claim 9.

11. An electrical device, the electrical device comprising: A battery pack; And The battery management system according to claim 10.

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