Battery balancing method, device, computer equipment, storage medium and program product

Abstract

The present application relates to a battery equalization method, device, computer equipment, storage medium and program product, which are applied in the field of battery technology. The method includes: obtaining the voltage change curve of each battery cell in the battery module when it is charged to the cut-off state, and determining the first reference battery cell in the battery module from multiple batteries in the battery module based on the voltage change curve of each battery cell; determining the first state of charge difference between the first reference battery cell in the battery module and other batteries in the battery module based on the voltage change curve of the first reference battery cell in the battery module; in the case of multiple battery modules, determining the second state of charge difference between any two adjacent battery modules; based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module, equalizing each battery cell in each battery module.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery balancing method, device, computer equipment, storage medium and program product. Background Art

[0002] In order to avoid the situation where the battery capacity cannot be effectively released due to the difference in the state of charge (SOC) between the cells in the battery module, the cells in the battery module can be balanced so that the SOC of each cell is consistent or the SOC difference is within an acceptable range. This helps to control the depth of battery charge and discharge, prevent overcharge and overdischarge of the battery, improve the available capacity and safety of the battery, and extend the battery life.

[0003] Generally, when balancing the cells, the imbalance of the cells can be eliminated by balancing a small amount each time and multiple times. However, this method has the problem of low balancing efficiency and low balancing accuracy. Summary of the invention

[0004] Based on this, it is necessary to provide a battery balancing method, device, computer equipment, storage medium and program product that can improve the balancing efficiency and accuracy in response to the above technical problems.

[0005] In the first aspect, the present application provides a battery balancing method. The method includes: obtaining the voltage change curve of each battery cell in the battery module when it is charged to the cut-off state, and determining the first reference battery cell in the battery module from the multiple batteries in the battery module based on the voltage change curve of each battery cell; determining the first state of charge difference between the first reference battery cell in the battery module and other batteries in the battery module based on the voltage change curve of the first reference battery cell in the battery module; in the case of multiple battery modules, for any two adjacent battery modules, determining the second state of charge difference between the two adjacent battery modules; based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module, balancing each battery cell in each battery module.

[0006] In the above embodiment, when one of the cells in the battery module is used as the first reference cell, the difference in state of charge between the first reference cell and other cells in the battery module can be calculated in real time based on the voltage change curve of the first reference cell, thereby avoiding the situation where the balancing accuracy is not high due to reliance on the OCV-SOC curve, and the balancing accuracy can be improved; moreover, when the difference in state of charge corresponding to each cell is known, the state of charge between the cells can be made consistent or the difference in state of charge is within an acceptable range through one balancing, and there is no need to perform multiple balancing, which can improve the balancing efficiency; moreover, on the basis of considering the difference in state of charge between the cells in a single battery module, when the number of battery modules is multiple, by further considering the difference in state of charge between adjacent battery modules, thereby, combining the difference in state of charge between the cells in a single battery module and the difference in state of charge between adjacent battery modules, each cell in each battery module is balanced, and the balancing accuracy can be improved.

[0007] In one embodiment, for any two adjacent battery modules, determining a second state of charge difference between the two adjacent battery modules includes: for any two adjacent battery modules, determining a temperature difference between the two adjacent battery modules; and determining a second state of charge difference between the two adjacent battery modules when the temperature difference is within a preset range.

[0008] In the above embodiment, by considering the temperature difference, the unsatisfactory balancing effect caused by ignoring the module temperature of the battery module can be avoided, so that the determined second state of charge difference will not produce errors due to the module temperatures of the two battery modules, thereby improving the accuracy of the determined second state of charge difference.

[0009] In one embodiment, the second state of charge difference between adjacent battery modules includes: a state of charge difference between first reference battery cells of two adjacent battery modules.

[0010] In the above embodiment, on the basis of considering the difference in charge state between the battery cells in a single battery module, by further considering the difference in charge state between the first reference battery cells in adjacent battery modules, the difference in charge state between the battery cells in all battery modules can be considered as a whole, and the balancing accuracy can be improved when balancing the battery cells in each battery module.

[0011] In one embodiment, a method for determining a state of charge difference between first reference cells of two adjacent battery modules includes: determining, for any two adjacent battery modules, a boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules; and determining a state of charge difference between the first reference cells of two adjacent battery modules based on the boundary state of charge difference between the two adjacent battery modules and a first state of charge difference corresponding to each cell in the two adjacent battery modules.

[0012] In the above embodiment, for any two adjacent battery modules, by determining the boundary state of charge difference between the boundary cells of adjacent modules in the two adjacent battery modules, the state of charge difference between the cells in the two adjacent battery modules can be associated with each other with the boundary state of charge difference as the medium, so that the balancing accuracy can be improved when the cells are balanced while considering the state of charge difference between the cells between the two battery modules as a whole.

[0013] In one embodiment, the voltage change curve includes N voltage rising curve segments; determining the boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules, including: for each module boundary cell, determining a first curve segment from the N voltage rising curve segments of the module boundary cell, wherein the difference in state of charge between the two ends of the first curve segment of the module boundary cell is the largest; from the first curve segments corresponding to the adjacent module boundary cells, determining the module boundary cell with the largest voltage at the start time of the first curve segment as the first boundary cell, and determining the remaining module boundary cells as the second boundary cells; determining a first mapping relationship between the maximum voltage matching the first boundary cell and the state of charge difference; wherein the first mapping relationship is obtained based on the divided sub-curve segments when the first curve segment of the first boundary cell is divided according to the first preset state of charge interval; based on the first mapping relationship, determining the state of charge difference matching the voltage at the end time of the first curve segment of the second boundary cell as the boundary state of charge difference between the adjacent module boundary cells of the two adjacent battery modules.

[0014] In the above embodiment, for adjacent module boundary cells, a first mapping relationship between the maximum voltage and the charge state difference is obtained by taking one of the module boundary cells as a reference, and then when the boundary charge state difference between adjacent module boundary cells of two adjacent battery modules is determined based on the first mapping relationship, the determination efficiency can be improved.

[0015] In one embodiment, based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module, each battery cell in each battery module is balanced, including: based on the state of charge difference between the first reference battery cells of all two adjacent battery modules, a second reference battery cell is determined from a plurality of first reference battery cells; based on the first state of charge difference corresponding to each battery cell in each battery module and the state of charge difference between the first reference battery cells of all two adjacent battery modules, a third state of charge difference between the second reference battery cell and each battery cell in each battery module is determined; based on the third state of charge difference corresponding to each battery cell in each battery module, a third reference battery cell is determined from a plurality of battery cells corresponding to a plurality of battery modules; based on the fourth state of charge difference between the third reference battery cell and each battery cell in each battery module and the first balancing current, a balancing time corresponding to each battery cell in each battery module is determined; based on the balancing time corresponding to each battery cell in each battery module, each battery cell in each battery module is balanced.

[0016] In the above embodiment, by taking the third reference battery cell with the smallest state of charge as a reference, when balancing the battery cells in each battery module, the state of charge of each battery cell can be kept consistent or the difference in the state of charge can be within an acceptable range, thereby facilitating the control of the battery charge and discharge depth, preventing overcharge and overdischarge of the power battery, improving the available capacity and safety of the battery, and extending the battery life.

[0017] In one embodiment, determining a second state of charge difference between two adjacent battery modules includes: determining a state of charge mean between a plurality of battery cells in each of the two adjacent battery modules; and determining a second state of charge difference between the two adjacent battery modules based on a state of charge difference between the state of charge means of the two adjacent battery modules.

[0018] In the above embodiment, the second state of charge difference between two adjacent battery modules can be determined from the perspective of the battery module as a whole, which can improve the determination efficiency.

[0019] In one embodiment, the second state of charge difference between two adjacent battery modules includes the state of charge difference between the state of charge means of the two adjacent battery modules; based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module, each battery cell in each battery module is balanced, including: based on the state of charge difference between the state of charge means of all adjacent battery modules, a target battery module is determined from multiple battery modules; the state of charge mean of the target battery module is the smallest; for other battery modules among the multiple battery modules except the target battery module, based on the fifth state of charge difference between the target battery module and the other battery modules, each battery cell in the other battery modules is balanced.

[0020] In the above embodiment, by taking the battery module as a whole, the balancing efficiency can be improved when the battery module is balanced while taking the difference in the state of charge between the cells between the two battery modules into consideration.

[0021] In one embodiment, a voltage change curve includes N voltage rising curve segments; based on the voltage change curves of each battery cell, a first reference battery cell in the battery module is determined from multiple battery cells in the battery module, including: for each battery cell in the battery module, a second curve segment is determined from the N voltage rising curve segments of the battery cell; wherein the voltage of the battery cell at the starting moment of the second curve segment is greater than or equal to a preset voltage and is less than the voltage at the starting moment of the remaining voltage rising curve segments of the battery cell; based on the voltages at the starting moment of the second curve segments of each of the multiple battery cells, the battery cell with the largest voltage is determined as the first reference battery cell.

[0022] In the above embodiment, the second target segment of each battery cell is determined by analyzing the N voltage rising curve segments of each battery cell. Thus, the first reference battery cell can be determined from the battery module in real time based on the second target segment of each battery cell, thereby improving the balancing accuracy.

[0023] In one embodiment, based on the voltage change curve of the first reference battery cell in the battery module, determining the first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module includes: determining a third curve segment from the N voltage rising curve segments of the first reference battery cell, the state of charge difference between the two ends of the third curve segment being the largest; obtaining a second mapping relationship between the maximum voltage matching the first reference battery cell and the state of charge difference; wherein the second mapping relationship is obtained based on the sub-curve segments obtained after the third curve segment is divided according to a second preset state of charge interval; for other battery cells in the battery module except the first reference battery cell, based on the second mapping relationship, the state of charge difference that matches the voltage of other battery cells in the cut-off state is determined as the first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module.

[0024] In the above embodiment, based on the third curve segment of the first reference battery cell, a second mapping relationship between the maximum voltage matching the first reference battery cell and the charge state difference can be obtained, and then when the first charge state difference between the first reference battery cell and other battery cells in the battery module is determined based on the second mapping relationship, the determination efficiency can be improved.

[0025] In a second aspect, the present application provides a battery balancing device, the device comprising: a first determination module, used to obtain the respective voltage change curves of each battery cell in the battery module when charged to a cut-off state, and determine a first reference battery cell in the battery module from multiple batteries in the battery module based on the voltage change curves of each battery cell; a second determination module, used to determine a first state of charge difference between the first reference battery cell in the battery module and other batteries in the battery module based on the voltage change curve of the first reference battery cell in the battery module; a processing module, used to determine a second state of charge difference between two adjacent battery modules for any two adjacent battery modules when there are multiple battery modules; and balancing each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module.

[0026] In a third aspect, the present application also provides a computer device. The computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the following steps when executing the computer program: obtaining the voltage change curve of each cell in the battery module when it is charged to the cut-off state, and determining the first reference cell in the battery module from multiple cells in the battery module based on the voltage change curve of each cell; determining the first state of charge difference between the first reference cell in the battery module and other cells in the battery module based on the voltage change curve of the first reference cell in the battery module; in the case of multiple battery modules, determining the second state of charge difference between any two adjacent battery modules; and performing equalization processing on each cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each cell in each battery module.

[0027] In a fourth aspect, the present application also provides a computer-readable storage medium. A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following steps are implemented: obtaining the voltage change curves of each battery cell in the battery module when it is charged to the cut-off state, and determining the first reference battery cell in the battery module from the multiple batteries in the battery module based on the voltage change curves of each battery cell; determining the first state of charge difference between the first reference battery cell in the battery module and other batteries in the battery module based on the voltage change curve of the first reference battery cell in the battery module; in the case of multiple battery modules, determining the second state of charge difference between any two adjacent battery modules; and performing equalization processing on each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module.

[0028] In a fifth aspect, the present application also provides a computer program product. The computer program product includes a computer program, which implements the following steps when executed by a processor: obtaining the voltage change curves of each battery cell in the battery module when it is charged to the cut-off state, and determining the first reference battery cell in the battery module from the multiple batteries in the battery module based on the voltage change curves of each battery cell; determining the first state of charge difference between the first reference battery cell in the battery module and other batteries in the battery module based on the voltage change curve of the first reference battery cell in the battery module; in the case of multiple battery modules, determining the second state of charge difference between any two adjacent battery modules; and performing equalization processing on each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module.

[0029] The battery balancing method, device, computer equipment, storage medium and program product can obtain the voltage change curve of each cell in the battery module when it is charged to the cut-off state. Based on the voltage change curve of each cell, a first reference cell in the battery module can be determined from multiple cells in the battery module, and based on the voltage change curve of the first reference cell in the battery module, a first state of charge difference between the first reference cell in the battery module and other cells in the battery module can be determined. Therefore, when one cell in the battery module is used as the first reference cell, the state of charge difference between the first reference cell and other cells in the battery module can be calculated in real time based on the voltage change curve of the first reference cell, thereby avoiding the situation where the balancing accuracy is low due to reliance on the OCV-SOC curve, and improving the balancing accuracy. Moreover, when the state of charge difference corresponding to each cell is known, the state of charge between the cells can be made consistent or the state of charge difference is within an acceptable range through one balancing, without the need for multiple balancing, and improving the balancing efficiency. Moreover, when there are multiple battery modules, by further considering the difference in charge state between adjacent battery modules, and thus combining the difference in charge state between battery cells in a single battery module and the difference in charge state between adjacent battery modules, each battery cell in each battery module is balanced, thereby improving the balancing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A diagram showing an application environment of a battery balancing method in an embodiment;

[0032] Figure 2 is a flowchart of a battery balancing method in one embodiment;

[0033] Figure 3 It is a schematic diagram of a process of performing balancing processing on each battery cell in a battery module based on a difference in first states of charge corresponding to each battery cell in the battery module in one embodiment;

[0034] Figure 4 It is a schematic diagram of a flow chart of determining a second state of charge difference between any two adjacent battery modules in one embodiment;

[0035] Figure 5It is a flowchart of a method for determining a difference in state of charge between first reference cells of two adjacent battery modules in one embodiment;

[0036] Figure 6 A schematic diagram of a process for determining a boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules in one embodiment;

[0037] Figure 7 It is a schematic diagram of a process of performing balancing processing on each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module in one embodiment;

[0038] Figure 8 A schematic diagram of a process for determining a second state of charge difference between two adjacent battery modules in one embodiment;

[0039] Fig. 9 It is a schematic diagram of a process of performing balancing processing on each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module in one embodiment;

[0040] Fig.10 A schematic diagram of a process for determining a first reference battery cell in a battery module from a plurality of battery cells in a battery module based on a voltage variation curve of each battery cell in an embodiment;

[0041] Fig.11 It is a schematic diagram of a process of determining a first state of charge difference between a first reference battery cell in a battery module and other battery cells in the battery module based on a voltage change curve of a first reference battery cell in a battery module in one embodiment;

[0042] Fig.12 is a flow chart of a battery balancing method according to another embodiment;

[0043] Fig.13 is a structural block diagram of a battery balancing device in one embodiment;

[0044] Fig.14 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0045] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0047] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0048] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0050] Generally, when balancing the cells in a battery module, the SOC difference between the cells can be obtained, and then the cells can be balanced based on the SOC difference between the cells. For example, the SOC difference between the cells can be obtained through the curve of the relationship between the battery open circuit voltage (OCV) and the state of charge (SOC).

[0051] However, only the slope of the OCV-SOC curve in the low-end area is obvious, and the end user rarely puts the vehicle at a low SOC. Therefore, it is difficult to obtain the SOC difference between each battery cell through the OCV-SOC curve in the low-end area. Moreover, the OCV-SOC curve is obtained by collecting relevant data statistics under low-end static conditions, which depends on low-end static conditions, but there are fewer low-end static conditions, and there are errors in identifying SOC differences through OCV.

[0052] As can be seen from the above, there are certain limitations when balancing the battery cells based on the OCV-SOC curve. Therefore, without considering the OCV-SOC curve, other methods can be used to balance the battery cells. For example, for the battery module entering the charging terminal, since the SOC difference of the same voltage difference under different charging rates varies greatly, the battery cells can be balanced by balancing a small amount each time and balancing multiple times. However, due to the uncertainty of the SOC difference between the battery cells, the method of balancing multiple times and balancing a small amount each time makes the balancing efficiency low and the balancing accuracy low.

[0053] After research, it was found that for the battery module entering the charging terminal, the voltage change curve of the battery cell can be obtained by dynamically identifying the battery cell voltage at the charging terminal, and then the SOC difference between the battery cells in the battery module can be calculated in real time, avoiding the low balancing accuracy due to reliance on the OCV-SOC curve. Therefore, the balancing accuracy can be provided; moreover, when the SOC difference between the battery cells is known, each battery cell can be balanced once based on the SOC difference between the battery cells, so that the SOC between the balanced battery cells can be consistent or the SOC difference can be within an acceptable range. There is no need to perform multiple balancing, which can improve the balancing efficiency.

[0054] In view of this, an embodiment of the present application provides a battery balancing method, which can be applied to Figure 1 In the application environment shown, the voltage acquisition device 104 is used to acquire the voltage of each battery cell in the battery module 106 when it is charged to the cut-off state, and send the voltage of each battery cell when it is charged to the cut-off state to the battery management system 102.

[0055] exist Figure 1 In the embodiment, the battery management system 102 obtains the voltage change curve of each battery cell in the battery module 106 when charged to the cut-off state based on the voltage of each battery cell when charged to the cut-off state collected by the voltage collection device 104, and determines a first reference battery cell in the battery module from multiple batteries in the battery module based on the voltage change curve of each battery cell, and determines a first state of charge difference between the first reference battery cell in the battery module and other batteries in the battery module based on the voltage change curve of the first reference battery cell in the battery module, and then balances each battery cell in the battery module based on the first state of charge difference corresponding to each battery cell in the battery module.

[0056] The voltage acquisition device 104 is a device for measuring and recording the cell voltage, and the communication method between the voltage acquisition device 104 and the battery management system 102 is not limited. In some cases, the voltage acquisition device 104 can communicate with the battery management system 102 via wireless or wired communication, and the wireless communication method includes but is not limited to: Wi-Fi, Bluetooth, Zigbee, Z-Wave, etc.

[0057] In one embodiment, Figure 2 As shown, a battery balancing method is provided, which is applied to Figure 1 The battery management system 102 in FIG. 1 is taken as an example to illustrate, and the following steps are included:

[0058] S202, obtaining a voltage variation curve of each battery cell in the battery module when the battery cell is charged to a cut-off state, and determining a first reference battery cell in the battery module from a plurality of battery cells in the battery module based on the voltage variation curve of each battery cell.

[0059] Among them, the voltage change curve refers to a graphical representation of the voltage change of the battery cell over time during the charging process; the cut-off state refers to the state in which the battery cell reaches its maximum capacity after being charged and stops charging. In some cases, the voltage of the battery cell during the charging process can be collected, and the voltage change curve of the battery cell can be obtained by statistics according to the voltage collection time. In other cases, the process of charging the battery cell to the cut-off state includes multiple charging stages. By collecting the voltage of the battery cell at each charging stage, the voltage change curve of the battery cell can be obtained by statistics according to the voltage collection time.

[0060] There is no limitation on the implementation method of determining the first reference battery cell in the battery module from the multiple battery cells in the battery module based on the voltage change curves of the battery cells. The following is an example of possible implementation methods.

[0061] In some embodiments, for the voltage change curve of each battery cell, a first reference battery cell can be determined from multiple battery cells based on the slope of the voltage change curve in the same time period. For example, from the voltage change curves of each of the multiple battery cells, a candidate curve segment from the charging start time to the preset time is determined; based on the curve slopes of the candidate curve segments of each battery cell, the battery cell with the largest slope is determined as the first reference battery cell in the battery module. The charging start time refers to the time when the battery cell starts charging.

[0062] It should be understood that when the slope of the candidate curve segment of a battery cell is larger, it means that the voltage rise trend of the battery cell is faster than that of other battery cells, and the rate at which the battery cell reaches the maximum voltage is higher than that of other battery cells. Usually, the battery cells in the battery module are connected in series, and the charging rate of each battery cell is consistent. In the same time period, it can be considered that the voltage path (that is, the relationship between voltage and SOC) of the battery cell with the maximum voltage is consistent with that of other battery cells. Therefore, when this battery cell is used as the first reference battery cell to obtain the first state of charge difference between the battery cells in the battery module, the accuracy of the obtained SOC difference can be improved, and the balancing accuracy can be further improved.

[0063] S204 , determining a first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module based on a voltage change curve of the first reference battery cell in the battery module.

[0064] There is no limitation on the implementation method of determining the first state of charge difference based on the voltage change curve of the first reference battery cell, and examples are given below in combination with possible implementation methods.

[0065] In some embodiments, the correspondence between voltage and state of charge can be obtained based on the voltage change curve of the first reference battery cell, and then based on the correspondence, the first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module can be determined.

[0066] Specifically, for other battery cells in the battery module, based on the correspondence between voltage and state of charge, the state of charge that matches the voltage of other battery cells in the cut-off state is determined as the candidate state of charge that matches the other battery cells, and the state of charge that matches the voltage of the first reference battery cell in the cut-off state is determined as the reference state of charge; the state of charge difference between the reference state of charge and the candidate state of charge is determined as the first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module.

[0067] S206 , performing balancing processing on the battery cells in the battery module based on the first state of charge difference corresponding to the battery cells in the battery module.

[0068] Among them, the balancing time corresponding to each battery cell can be determined based on the difference in the first state of charge corresponding to each battery cell in the battery module, and the battery cells in the battery module can be balanced based on the balancing time corresponding to each battery cell. The balancing time represents the total time required for the battery cell to reach a preset balanced state. The preset balanced state refers to the state of charge of each battery cell in the battery module reaching a consistent state, or the state of charge difference of each battery cell value in the battery module is within an acceptable range. Specifically, the balancing time refers to the time for discharging the battery cell.

[0069] In some embodiments, the balancing time corresponding to each battery cell may be determined based on the first state of charge difference corresponding to each battery cell and the first balancing current. For example, the ratio of the first state of charge difference to the first balancing current is determined as the balancing time.

[0070] In some embodiments, the balancing time corresponding to each battery cell may also be determined based on the corresponding relationship between the state of charge difference and the balancing time, and the first state of charge difference corresponding to each battery cell.

[0071] In some embodiments, the balancing time coefficient corresponding to each battery cell can be determined based on the corresponding relationship between the state of charge difference and the balancing time coefficient and the first state of charge difference corresponding to each battery cell; and the balancing time corresponding to each battery cell can be determined based on the balancing time coefficient corresponding to each battery cell and the preset time. For example, the balancing time is the product of the preset time and the balancing time coefficient.

[0072] based on Figure 2 The content shown is that by obtaining the respective voltage change curves of each battery cell in the battery module when it is charged to the cut-off state, based on the voltage change curves of each battery cell, a first reference battery cell in the battery module can be determined from multiple battery cells in the battery module, and based on the voltage change curve of the first reference battery cell in the battery module, a first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module can be determined. Therefore, in the case where one battery cell in the battery module is taken as the first reference battery cell, the state of charge difference between the first reference battery cell and other battery cells in the battery module can be calculated in real time based on the voltage change curve of the first reference battery cell, thereby avoiding the situation where the balancing accuracy is low due to reliance on the OCV-SOC curve, and the balancing accuracy can be improved; moreover, in the case where the state of charge difference corresponding to each battery cell is known, the state of charge between the battery cells can be made consistent or the state of charge difference can be within an acceptable range through one balancing, and there is no need to perform multiple balancing, which can improve the balancing efficiency.

[0073] In one embodiment, there are multiple battery modules. For each battery module, based on Figure 2 The method shown in FIG. 1 can obtain the first reference cell in each battery module and the charge state difference between the first reference cell and other cells in each battery module. In some embodiments, based on the first charge state difference corresponding to each cell in the battery module, the implementation method of performing equalization processing on each cell in the battery module (i.e., S206) can be as follows: Figure 3 As shown, the following steps are included:

[0074] S302: for any two adjacent battery modules, determine a second state of charge difference between the two adjacent battery modules.

[0075] There is no limitation on the manner of determining the difference in the second state of charge between any two adjacent battery modules, and several of the manners are described below by way of example.

[0076] In some embodiments, the second SOC difference may represent the SOC difference between the cells in two adjacent battery modules. For example, the SOC difference between any two cells in two adjacent battery modules may be used as the SOC difference between the two adjacent battery modules.

[0077] In some embodiments, the second state of charge difference can characterize the state of charge difference between the entire modules of two adjacent battery modules. For example, the voltage average of multiple cells in each battery module in the cut-off state can be determined; based on the corresponding relationship between the voltage and the state of charge difference, the difference between the states of charge that match the voltage average of the two battery modules is determined as the second state of charge difference between the two adjacent battery modules.

[0078] S304 , performing balancing processing on each battery cell in each battery module based on the second state of charge differences between all adjacent battery modules and the first state of charge differences corresponding to each battery cell in each battery module.

[0079] Among them, when the meanings represented by the second state of charge differences between adjacent battery modules are different, combined with the first state of charge differences corresponding to each battery cell in each battery module, the implementation methods of balancing each battery cell in each battery module are different, and several of these methods are given as examples below.

[0080] In one embodiment, in combination with S302, when the state of charge difference between any two battery cells in two adjacent battery modules is used as the state of charge difference between the two adjacent battery modules, a first reference battery cell is determined from all any two battery cells based on the state of charge difference between any two battery cells in all two adjacent battery modules, and the voltage mean value of the first reference battery cell during the charging process is the smallest; for the remaining battery cells in multiple battery modules except the first reference battery cell, the balancing time corresponding to the remaining battery cells is determined based on the state of charge difference between the first reference battery cell and the remaining battery cells; and the remaining battery cells are balanced based on the balancing time corresponding to the remaining battery cells.

[0081] The charging process of the battery cell refers to the process from the start of charging to the stop of charging of the battery cell. The difference in state of charge between the first reference battery cell and the remaining battery cells can be determined based on the difference in state of charge between the first reference battery cell and other battery cells in the battery module where the first remaining battery cell is located, and the difference in the second state of charge between all adjacent battery modules.

[0082] In one embodiment, in combination with S302, when the difference between the charge states that matches the voltage mean of two adjacent battery modules is taken as the charge state difference between the two adjacent battery modules, a reference battery module is determined from multiple battery modules based on the charge state differences between all two adjacent battery modules, and the voltage mean of the reference battery module is the smallest; for other battery modules among the multiple battery modules except the reference battery module, the balancing time corresponding to the other battery modules is determined based on the charge state differences between the reference battery module and the other battery modules; and each battery cell in the other battery modules is balanced based on the balancing time corresponding to the other battery modules.

[0083] In some embodiments, when the balancing time corresponding to other battery modules is obtained, the balancing time corresponding to other modules can be divided based on the reference state of charge of each battery cell in other battery modules to obtain the sub-balancing time corresponding to each battery cell, and then the sub-balancing time corresponding to each battery cell is balanced. The larger the reference state of charge of the battery cell, the smaller the sub-balancing time corresponding to the battery cell, and the sum of the sub-balancing time of each battery cell in other battery modules is consistent with the balancing time corresponding to other battery modules.

[0084] Among them, the type of reference state of charge of the battery cell is not limited. For example, in some embodiments, the state of charge of the battery cell in the cut-off state can be used as the reference state of charge of the battery cell. In other embodiments, the average state of charge of the battery cell during the charging process can be used as the reference state of charge of the battery cell.

[0085] based on Figure 3 The method shown, on the basis of considering the difference in charge state between the battery cells in a single battery module, further considers the difference in charge state between adjacent battery modules when the number of battery modules is multiple. Thus, by combining the difference in charge state between the battery cells in a single battery module and the difference in charge state between adjacent battery modules, each battery cell in each battery module is balanced, thereby improving the accuracy of balancing.

[0086] Combination Figure 3 As can be seen from the content shown, for any two adjacent battery modules, the second state of charge difference between the two adjacent battery modules can be determined. In order to improve the accuracy of the determined second state of charge difference, the second state of charge difference between the two adjacent battery modules can also be determined while considering the temperature difference between the two adjacent battery modules. Specifically, Figure 4 As shown, a flow chart of determining a second state of charge difference between any two adjacent battery modules (ie, S302) is provided, including the following steps:

[0087] S402: For any two adjacent battery modules, determine the temperature difference between the two adjacent battery modules.

[0088] The temperature difference between two adjacent battery modules may be represented in various possible forms, several of which are illustrated below.

[0089] In some embodiments, the temperature difference between adjacent module boundary cells in two adjacent battery modules can be used as the temperature difference between two adjacent battery modules. For example, the temperature difference between module boundary cells can refer to the difference between the temperatures of the module boundary cells in the cut-off state, or the difference between module boundary cells can refer to the difference between the temperature averages of the module boundary cells during the charging process.

[0090] In other embodiments, the temperature average of multiple cells in each battery module can be determined, and the difference between the temperature averages corresponding to two adjacent battery modules is used as the temperature difference between the two adjacent battery modules. The temperature average of multiple cells in a battery module can refer to the average temperature of multiple cells in the battery module when they are in the cutoff state, or, when the temperature average of each cell during the charging process is counted, the average of the temperature averages of multiple cells is used as the temperature average of multiple cells in the battery module.

[0091] For example, the battery includes a first battery cell, a second battery cell, a third battery cell, a fourth battery cell, a fifth battery cell and a sixth battery cell which are connected in series in sequence, the first battery cell, the second battery cell and the third battery cell are located in a first battery module, the fourth battery cell, the fifth battery cell and the sixth battery cell are located in a second battery module, the first battery module and the second battery module are adjacent, the module boundary cell in the first battery module is the third battery cell, and the module boundary cell in the second battery module is the fourth battery cell, then the difference between the temperatures of the third battery cell and the fourth battery cell in the cut-off state can be used as the temperature difference between the first battery module and the second battery module.

[0092] Alternatively, the temperature averages of the first to sixth battery cells during the charging process are respectively the first to sixth averages; the first temperature value can be obtained by calculating the average of the first to third averages, and the second temperature value can be obtained by calculating the average of the fourth to sixth averages, and the temperature difference between the first temperature value and the second temperature value can be used as the temperature difference between the first battery module and the second battery module.

[0093] S404: When the temperature difference is within a preset range, determine a second state of charge difference between two adjacent battery modules.

[0094] Among them, when the temperature difference is within the preset range, it means that the temperature difference between the two battery modules is small, and the module temperature of the two battery modules has little effect on determining the second state of charge difference between the two adjacent battery modules. In other words, when the temperature difference is within the preset range, the module temperature of the two battery modules can be ignored to determine the second state of charge difference between the two adjacent battery modules.

[0095] based on Figure 4 The content shown, for any two adjacent battery modules, can determine the second state of charge difference between the two adjacent battery modules when the temperature difference between the two adjacent battery modules is within a preset range. Thus, by considering the temperature difference, it is possible to avoid the situation where an unsatisfactory balancing effect is caused by ignoring the module temperature of the battery modules, so that the determined second state of charge difference will not produce errors due to the module temperatures of the two battery modules, thereby improving the accuracy of the determined second state of charge difference.

[0096] Based on the above, when there are multiple battery modules, for any two adjacent battery modules, the second state of charge difference between the two adjacent battery modules can be determined based on the difference in state of charge between any two cells in the two adjacent battery modules, or based on the difference between the states of charge that match the voltage mean of the two adjacent battery modules. In another embodiment, the second state of charge difference between the two adjacent battery modules can also be determined by considering the first reference cell in the battery module.

[0097] Specifically, the second state of charge difference between adjacent battery modules includes: the state of charge difference between the first reference cells of two adjacent battery modules. Therefore, on the basis of considering the state of charge difference between the cells in a single battery module, by further considering the state of charge difference between the first reference cells in adjacent battery modules, the state of charge difference between the cells in all battery modules can be considered as a whole, and when performing balancing processing on the cells in each battery module, the balancing accuracy can be improved.

[0098] In some cases, the difference in state of charge between the first reference cells of two adjacent battery modules may be determined as the difference in the second state of charge between the two adjacent battery modules.

[0099] There is no limitation on the manner of determining the difference in the state of charge between the first reference cells of two adjacent battery modules, and several of the manners are described below by way of example.

[0100] In one embodiment, the voltage variation curve includes M voltage rising curve segments. For each first reference cell in two adjacent battery modules, the charge state difference between the first reference cells of the two adjacent battery modules can be determined based on the M voltage rising curve segments of the first reference cells.

[0101] The starting and ending times of the voltage rising curve segments between different battery cells are kept consistent, that is, the difference between the voltage rising curve segments between different battery cells is that the voltage rising trends are different, but the starting and ending times of the voltage rising curve segments are kept consistent.

[0102] Specifically, for each first reference battery cell, a first candidate segment is determined from the M voltage rising curve segments of the first reference battery cell, and the voltage difference between the two ends of the first candidate segment of the first reference battery cell is the largest; the voltage difference corresponding to the first candidate segments of the two first reference battery cells is compared, and the first candidate segment of the first reference battery cell with the larger voltage difference is determined as the second candidate segment, and the first candidate segment of the first reference battery cell with the smaller voltage difference is determined as the third candidate segment.

[0103] In some embodiments, the second candidate segment is divided according to the first set state of charge interval, and based on the change relationship between the voltage and the state of charge at both ends of the sub-curve segment obtained after the division, a first corresponding relationship between the voltage and the state of charge difference is obtained. Therefore, based on the first corresponding relationship, the state of charge difference that matches the voltage of the first reference battery cell in the cut-off state where the third candidate segment is located is determined as the state of charge difference between the first reference batteries of the two adjacent battery modules.

[0104] In another implementation, for each first reference cell in two adjacent battery modules, based on the voltage of the first reference cell in the cut-off state, the first reference cell with a larger voltage is determined as the first basic cell, and the first reference cell with a smaller voltage is determined as the second basic cell; from the N voltage rising curve segments of the first basic cell, a basic curve segment is determined, and the charge state difference between the two ends of the basic curve segment of the first reference cell is the largest.

[0105] In some embodiments, the basic curve segment is divided according to the second set state of charge interval, and based on the change relationship between the voltage and the state of charge at both ends of the sub-curve segment obtained after the division, a second corresponding relationship between the voltage and the state of charge difference matching the first basic battery cell is obtained. Therefore, based on the second corresponding relationship, the state of charge difference matching the voltage of the second basic battery cell in the cut-off state is determined as the state of charge difference between the first reference batteries of the two adjacent battery modules.

[0106] Based on the above, when the voltage change curve includes M voltage rise curves, the state of charge difference between the first reference cells of two adjacent battery modules can be determined directly based on the voltage change curve of the first reference cell. In other embodiments, the state of charge difference between the first reference cells of two adjacent battery modules can also be determined by using the adjacent module boundary cells in the two adjacent battery modules as an intermediary. Specifically, Figure 5 As shown, the following steps are included:

[0107] S502 : For any two adjacent battery modules, determine a boundary state of charge difference between adjacent module boundary cells of the two adjacent battery modules.

[0108] There is no limitation on the implementation method of determining the boundary state of charge difference between the boundary cells of two adjacent battery modules, and several of the methods are described below as examples.

[0109] In one embodiment, for each module boundary cell, the state of charge mean of the module boundary cell during the charging process is counted; and the difference between the state of charge mean values ​​of adjacent module boundary cells is determined as the boundary state of charge difference between adjacent module boundary cells.

[0110] In one embodiment, for each module boundary cell, based on the correlation between voltage and charge state, a charge state that matches the voltage of the module boundary cell in the cut-off state is determined; and the difference between the charge states of adjacent module boundary cells is determined as the boundary charge state difference between adjacent module boundary cells.

[0111] S504, determining a state of charge difference between first reference cells of two adjacent battery modules based on a boundary state of charge difference between two adjacent battery modules and a first state of charge difference corresponding to each cell in two adjacent battery modules.

[0112] Among them, for two adjacent battery modules, when the first state of charge difference corresponding to each battery cell in the battery module is known, the boundary state of charge difference between the boundary batteries of adjacent modules can be used as a medium to consider the charge state difference between the batteries in the two battery modules as a whole.

[0113] For example, the first battery module includes the first battery cell, the second battery cell and the third battery cell, the second battery module includes the fourth battery cell, the fifth battery cell and the sixth battery cell, the module boundary cell in the first battery module is the third battery cell, and the module boundary cell in the second battery module is the fourth battery cell. Assuming that the first reference battery cell in the first battery module is the second battery cell, and the first reference battery cell in the second battery module is the fifth battery cell, the difference in state of charge between the second battery cell and the first battery cell is expressed as the second battery cell is 1% higher than the first battery cell, the difference in state of charge between the second battery cell and the third battery cell is expressed as the second battery cell is 2% higher than the third battery cell, the difference in state of charge between the fifth battery cell and the fourth battery cell is expressed as the fifth battery cell is 1% higher than the fourth battery cell, the difference in state of charge between the fifth battery cell and the sixth battery cell is expressed as the fifth battery cell is 2% higher than the sixth battery cell, and the fourth battery cell is 1% lower than the third battery cell.

[0114] Based on the differences in the state of charge between the above-mentioned battery cells, it can be determined that since the fourth battery cell is 1% lower than the third battery cell and the fifth battery cell is 1% higher than the fourth battery cell, the state of charge of the fifth battery cell and the third battery cell are the same, and since the second battery cell is 2% higher than the third battery cell, the second battery cell is 2% higher than the fifth battery cell, that is, the difference in the state of charge between the first reference battery cells is 2%.

[0115] based on Figure 5 The content shown is that, for any two adjacent battery modules, by determining the boundary state of charge difference between the adjacent module boundary cells in the two adjacent battery modules, the charge state difference between the cells in the two adjacent battery modules can be associated with the boundary state of charge difference as the medium, so that when the charge state difference between the cells between the two battery modules is considered as a whole, the balancing accuracy can be improved when the cells are balanced.

[0116] Based on S502, it can be known that the difference in the charge state of the boundary cells between the modules can be determined based on the difference between the charge state averages of the adjacent module boundary cells, or based on the voltage of the module boundary cells in the cut-off state. In another embodiment, when the voltage change curve includes N voltage rising curve segments, the following method can also be used: Figure 6 The method shown in the figure determines the boundary state of charge difference between the boundary cells of two adjacent battery modules, including the following steps:

[0117] S602 , for each module boundary cell, determine a first curve segment from the N voltage rising curve segments of the module boundary cell, where the difference in state of charge of the module boundary cell between two ends of the first curve segment is the largest.

[0118] Among them, the N voltage rise curve segments of the module boundary cells are the voltage rise curve segments selected from the M voltage rise curve segments of the module boundary cells. For example, for each of the M voltage rise curve segments, the voltage rise curve segment is divided according to the first preset state of charge interval to obtain sub-curve segments; from the M voltage rise curve segments, the voltage rise curve segments whose number of sub-curve segments is less than the preset number are deleted to obtain N voltage rise curve segments, that is, in the N voltage rise curve segments, the number of sub-curve segments obtained after each voltage rise curve segment is divided according to the first preset state of charge interval is greater than or equal to the preset number.

[0119] In some embodiments, for the N voltage rising curve segments of the boundary cells of each module, the state of charge difference between the two ends of each voltage rising curve segment is determined, so that the voltage rising curve segment with the largest state of charge difference is determined as the first curve segment.

[0120] There is no limitation on the method for determining the difference in state of charge between the two ends of the voltage rise curve segment. In some embodiments, the state of charge of the voltage matching at the two ends of the voltage rise curve segment can be determined based on the correlation between voltage and state of charge; the difference between the state of charge matching the voltage at the two ends is determined as the difference in state of charge between the two ends of the voltage rise curve segment. In other embodiments, the difference in state of charge between the two ends of the module boundary cell at the voltage rise curve segment can be determined by the ratio of the amount of Ah (i.e., electricity) charged into the module boundary cell at the voltage rise curve segment to the rated capacity of the module boundary cell.

[0121] S604 , from the first curve segments corresponding to the adjacent module boundary cells, determine the module boundary cell with the largest voltage at the start time of the first curve segment as the first boundary cell, and determine the remaining module boundary cells as the second boundary cells.

[0122] S606, determining a first mapping relationship between a maximum voltage matching the first boundary battery cell and a state of charge difference; wherein the first mapping relationship is obtained based on the divided sub-curve segments when the first curve segment of the first boundary battery cell is divided according to a first preset state of charge interval.

[0123] There is no limitation on the way of obtaining the first mapping relationship, which is described below with examples in combination with possible implementation methods.

[0124] In one embodiment, the first curve segment of the first boundary battery cell is divided according to a first preset state of charge interval to obtain multiple sub-curve segments; for each sub-curve segment, the state of charge difference at both ends of the sub-curve segment and the maximum voltage at both ends of the sub-curve are determined; based on the state of charge difference and the maximum voltage corresponding to the multiple sub-curve segments, a first mapping relationship between the maximum voltage and the state of charge difference is obtained.

[0125] There is no limitation on the implementation method of determining the difference in state of charge between the two ends of the sub-curve. For example, reference may be made to the method of determining the difference in state of charge between the two ends of the voltage rising curve segment of the module boundary cells in S602.

[0126] For example, assuming that the voltages at both ends of a sub-curve segment are A1 and A2, respectively, A2 is greater than A1, and the state of charge difference when the first boundary cell is charged from A1 to A2 is B, then the relationship between the maximum voltages A2 and B can be obtained. Furthermore, through the correlation relationship between the maximum voltages and the state of charge differences corresponding to the multiple sub-curve segments, a first mapping relationship between the maximum voltage and the state of charge difference can be obtained.

[0127] S608 , based on the first mapping relationship, determining the state of charge difference that matches the voltage at the end moment of the first curve segment of the second boundary cell as the boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules.

[0128] Among them, when the voltage at the start time of the first curve segment of the first boundary cell is greater than the voltage at the start time of the first curve segment of the second boundary cell, then for other moments of the first curve segment except the start time, the voltage of the first boundary cell at other moments is also greater than the voltage of the second boundary cell at other moments, that is, the voltage of the first boundary cell at any moment of the first curve segment is greater than the voltage of the second boundary cell at any moment of the first curve segment. Therefore, based on the first mapping relationship, when determining the charge state difference that matches the voltage at the end time of the first curve segment of the second boundary cell, the boundary charge state difference between the first boundary cell and the second boundary cell is determined from the perspective of the maximum voltage of the first boundary cell.

[0129] Specifically, the first mapping relationship includes multiple maximum voltages and the charge state difference corresponding to each maximum voltage, then the maximum voltage that matches the voltage at the end moment of the first curve segment of the second boundary battery cell is determined from the multiple maximum voltages in the first mapping relationship; the charge state difference that matches the determined maximum voltage in the first mapping relationship is determined as the charge state difference between the first boundary battery cell and the second boundary battery cell, that is, the boundary charge state difference between adjacent module boundary cells of two adjacent battery modules.

[0130] Among them, the first curve segment is a curve segment among N voltage rising curve segments, and the number of sub-curve segments obtained after dividing the first curve segment according to the first preset state of charge interval is also greater than or equal to the preset number. When the first preset state of charge interval is set to be small, a sufficient number of relationships between the maximum voltage and the state of charge difference can be obtained. Then, based on the first mapping relationship, when determining the boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules, the determination accuracy can be improved.

[0131] based on Figure 6 The method shown, for adjacent module boundary cells, obtains a first mapping relationship between the maximum voltage and the charge state difference by taking one of the module boundary cells as a reference, and then determines the boundary charge state difference between adjacent module boundary cells of two adjacent battery modules based on the first mapping relationship, which can improve the determination efficiency.

[0132] Based on the above, it can be known that the state of charge difference between the first reference cells of two adjacent battery modules can be determined based on the state of charge difference between the boundary cells of two adjacent modules, thereby, the state of charge difference between the first reference cells of two adjacent battery modules can be determined as the second state of charge difference between the adjacent battery modules.

[0133] In some embodiments, Figure 7 As shown, a schematic diagram of a process for balancing each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module is provided, including the following steps:

[0134] S702 , determining a second reference cell from a plurality of first reference cells based on the difference in charge states between the first reference cells of all two adjacent battery modules.

[0135] Among them, based on the difference in charge states between the first reference cells of all two adjacent battery modules, a first reference cell with the smallest charge state and a first reference cell with the largest charge state can be determined from multiple first reference cells, and the first reference cell with the largest charge state is determined as the second reference cell, that is, the second reference cell is the first reference cell with the largest charge state among the multiple first reference cells.

[0136] For example, the first battery module includes a first battery cell, a second battery cell and a third battery cell, the second battery module includes a fourth battery cell, a fifth battery cell and a sixth battery cell, and the third battery module includes a seventh battery cell, an eighth battery cell and a ninth battery cell; assuming that the first reference battery cell in the first battery module is the first battery cell, the first reference battery cell in the second battery module is the fourth battery cell, and the first reference battery cell in the third battery module is the seventh battery cell; assuming that the difference in state of charge between the first battery cell and the fourth battery cell is expressed as the first battery cell is 2% lower than the fourth battery cell, and the difference in state of charge between the fourth battery cell and the seventh battery cell is expressed as the fourth battery cell is 1% lower than the seventh battery cell, then it can be determined that the first battery cell is the battery cell with the smallest state of charge, and the seventh battery cell is the battery cell with the largest state of charge, and the seventh battery cell is determined as the second reference battery cell.

[0137] S704, determining a third state of charge difference between a second reference cell and each cell in each battery module based on the first state of charge difference corresponding to each cell in each battery module and the state of charge difference between the first reference cells of all two adjacent battery modules.

[0138] In this embodiment, the charge state difference between the first reference cells of all two adjacent battery modules includes the charge state difference between the first reference cell in the battery module where the second reference cell is located and the first reference cell in the adjacent battery module.

[0139] Specifically, for other cells in the battery module where the second reference cell is located, the first state of charge differences corresponding to the other cells are determined as the third state of charge differences between the second reference cell and the other cells.

[0140] Specifically, for other battery cells except the battery module where the second reference battery cell is located, the third state of charge difference between the second reference battery cell and each battery cell in an adjacent battery module can be determined based on the charge state difference between the battery module where the second reference battery cell is located and the second reference battery cell in an adjacent battery module, and the first state of charge difference between the first reference battery cell and other battery cells in the adjacent battery module.

[0141] In some embodiments, for battery modules adjacent to adjacent battery modules, a third state of charge difference between a second reference cell and each cell in a battery module adjacent to an adjacent battery module can be determined based on the state of charge difference between the adjacent battery module and the first reference cell in the battery module adjacent to it, and the first state of charge difference between the first reference cell and other cells in the battery module adjacent to the adjacent battery module, and so on, to obtain the third state of charge difference between the second reference cell and each cell in each battery module.

[0142] S706 , based on the difference in the third state of charge corresponding to each battery cell in each battery module, determine a third reference battery cell from the multiple battery cells corresponding to the multiple battery modules.

[0143] Among them, the second reference battery cell refers to the first reference battery cell with the largest state of charge among multiple first reference battery cells, and the difference in the third state of charge corresponding to the battery cell represents the difference in state of charge between the battery cell and the battery cell with the largest state of charge. Therefore, when the difference in the third state of charge corresponding to the battery cell is smaller, it can be said that the state of charge of the battery cell is closer to the largest state of charge. Conversely, when the difference in the third state of charge corresponding to the battery cell is larger, it can be said that the state of charge of the battery cell is farther from the largest state of charge, that is, the state of charge of the battery cell is the smallest state of charge. Therefore, the third reference battery cell can be determined by comparing the size of the third state of charge.

[0144] Specifically, based on the difference in the third state of charge corresponding to each battery cell in each battery module, a battery cell having the largest difference in the third state of charge among the multiple battery cells corresponding to the multiple battery modules is determined as the third reference battery cell.

[0145] S708: Determine a balancing time corresponding to each cell in each battery module based on a fourth state of charge difference between the third reference cell and each cell in each battery module, and the first balancing current.

[0146] For the first reference cell in the battery module where the third reference cell is located, a first state of charge difference between the first reference cell and the third reference cell is determined as a fourth state of charge difference between the third reference cell and the first reference cell.

[0147] For other battery cells except the first reference battery cell in the battery module where the third reference battery cell is located, based on the first state of charge difference between the first reference battery cell and the other battery cells, and the fourth state of charge between the third reference battery cell and the first reference battery cell, determine the fourth state of charge difference between the third reference battery cell and the other battery cells.

[0148] For other battery cells outside the battery module where the third reference battery cell is located, the fourth state of charge difference between the third reference battery cell and the first reference battery cell in the battery module where the third reference battery cell is located, the state of charge difference between the battery module where the third reference battery cell is located and the first reference battery cell in an adjacent battery module, and the first state of charge difference between the first reference cell and other battery cells in adjacent battery modules are determined.

[0149] In some embodiments, the fourth state of charge difference between the third reference cell and each cell in the battery module adjacent to the adjacent battery module can be determined based on the fourth state of charge difference between the third reference cell and each cell in an adjacent battery module, the state of charge difference between an adjacent battery module and the first reference cell in the battery module adjacent to it, and the first state of charge difference between the first reference cell and other cells in a battery module adjacent to an adjacent battery module, and so on, to obtain the fourth state of charge difference between the third reference cell and each cell in each battery module.

[0150] In some embodiments, when the fourth state of charge difference corresponding to each battery cell in each battery module is obtained, the balancing time corresponding to each battery cell may be determined based on the fourth state of charge difference corresponding to each battery cell.

[0151] There is no limitation on the method of determining the balancing time corresponding to the battery cells based on the fourth state of charge difference corresponding to the battery cells. For example, reference may be made to the method of determining the balancing time corresponding to the battery cells based on the first state of charge difference corresponding to the battery cells in S206.

[0152] S710, performing balancing processing on each battery cell in each battery module based on the balancing time corresponding to each battery cell in each battery module.

[0153] For the balancing time corresponding to each battery cell, the battery cell may be discharged based on the balancing time corresponding to the battery cell, and the discharge time is consistent with the balancing time.

[0154] based on Figure 7 The method shown can determine a second reference cell with the largest state of charge from multiple first reference cells based on the difference in state of charge between the first reference cells of all two adjacent battery modules, and can determine a third reference cell with the smallest state of charge from multiple cells corresponding to the multiple battery modules based on the difference in third state of charge between the second reference cell and each cell in each battery module. Therefore, when the cells in each battery module are balanced with reference to the third reference cell with the smallest state of charge, the state of charge of each cell can be kept consistent or the difference in state of charge is within an acceptable range, which helps to control the depth of charge and discharge of the battery, prevent overcharge and overdischarge of the power battery, improve the available capacity and safety of the battery, and extend the battery life.

[0155] Based on the above, when the temperature difference between two adjacent battery modules is within a preset range, the second state of charge difference between the two adjacent battery modules can be determined from the dimension of a single battery cell. In other embodiments, the battery module can also be taken as a whole to determine the second state of charge difference between the two adjacent battery modules. Specifically, Figure 8As shown, a schematic diagram of a process for determining a second state of charge difference between two adjacent battery modules is provided, comprising the following steps:

[0156] S802, determining an average state of charge of a plurality of battery cells in each of two adjacent battery modules.

[0157] Therein, for each battery module in two adjacent battery modules, there is no limitation on the manner of determining the average state of charge between a plurality of battery cells in the battery module, and several of the manners are described below by way of example.

[0158] In some embodiments, the state of charge of each battery cell in the cut-off state is obtained, and the average state of charge of multiple battery cells in the cut-off state is calculated to obtain the average state of charge of the battery module.

[0159] In other embodiments, the state of charge average of each battery cell during the charging process is obtained; the state of charge average of multiple battery cells during the charging process is averaged to obtain the state of charge average of the battery module.

[0160] S804: Determine a second state of charge difference between two adjacent battery modules based on a state of charge difference between the state of charge means of two adjacent battery modules.

[0161] There is no limitation on the manner of determining the difference in the second state of charge between two adjacent battery modules based on the mean state of charge of the battery modules, and several of the manners are described below by way of example.

[0162] In one embodiment, the state of charge difference between the state of charge means of two adjacent battery modules may be determined as the second state of charge difference between the two adjacent battery modules.

[0163] In other embodiments, for the state of charge difference between the state of charge means of two adjacent battery modules, when the state of charge difference is greater than a preset difference, the product of the preset difference and a preset coefficient is determined as the second state of charge difference between the two adjacent battery modules; when the state of charge difference is less than or equal to the preset difference, the mean of the preset difference and the state of charge difference is determined as the second state of charge difference between the two adjacent battery modules.

[0164] based on Figure 8 The method shown can determine the second state of charge difference between two adjacent battery modules from the perspective of the battery module as a whole, which can improve the determination efficiency.

[0165] In some embodiments, when the second state of charge difference between two adjacent battery modules includes a state of charge difference between the state of charge means of the two adjacent battery modules, as Fig. 9As shown, a schematic diagram of a process for balancing each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module is provided, including the following steps:

[0166] S902 : Determine a target battery module from a plurality of battery modules based on a state of charge difference between the average state of charge values ​​of all adjacent battery modules.

[0167] Among them, based on the difference in charge state between the first reference cells of all two adjacent battery modules, the battery module with the smallest average charge state is determined as the target battery module from multiple battery modules, that is, the average charge state of the target battery module is smaller than the average charge state of other battery modules.

[0168] S904 , for other battery modules except the target battery module among the multiple battery modules, based on the fifth state of charge difference between the target battery module and the other battery modules, perform balancing processing on each battery cell in the other battery modules.

[0169] The difference in state of charge between the target battery module and other battery modules may be determined based on the difference in state of charge between the average values ​​of the states of charge of all adjacent battery modules.

[0170] For example, for a battery module adjacent to the target battery module, the second state of charge difference between the target battery module and the adjacent battery module is determined as the fifth state of charge difference between the target battery module and the adjacent battery module.

[0171] For the battery modules adjacent to the adjacent battery modules, based on the fifth state of charge difference between the target battery module and the adjacent battery modules and the second state of charge difference between the adjacent battery module and the battery modules adjacent to it, the fifth state of charge difference between the target battery module and the battery modules adjacent to it can be determined, and so on, the fifth state of charge difference between the target battery module and other battery modules can be obtained.

[0172] In some embodiments, when a fifth state of charge difference is obtained between the target battery module and other battery modules, the target battery module is not balanced, and each battery cell in other battery modules is balanced based on the corresponding balancing time of other battery modules.

[0173] There is no limitation on the manner of determining the balancing time corresponding to other battery modules based on the difference in the fifth state of charge corresponding to other battery modules, and several of the manners are described below by way of example.

[0174] In some embodiments, the ratio of the fifth state of charge difference corresponding to other battery modules to the second balancing current can be determined as the balancing time corresponding to other battery modules. The first balancing current and the second balancing current can be the same or different.

[0175] In some embodiments, based on the correspondence between the state of charge difference and the balancing time, the balancing time that matches the fifth state of charge difference corresponding to other battery modules may be determined as the balancing time corresponding to other battery modules.

[0176] In some embodiments, when the balancing time corresponding to other battery modules is obtained, each battery cell in the other battery modules can be balanced based on the balancing time corresponding to other battery modules. The specific implementation method can refer to the relevant content adaptation description in S304 and will not be repeated here.

[0177] based on Fig. 9 The content shown, by taking the battery module as a whole, can improve the balancing efficiency when the battery modules are balanced while taking into account the difference in charge state between the cells between the two battery modules as a whole.

[0178] Based on the above, for the voltage change curve of each battery cell in the battery module, a first reference battery cell can be determined from multiple battery cells based on the slope of the voltage change curve in the same time period. In another embodiment, when the voltage change curve includes N voltage rising curve segments, the first reference battery cell can also be determined from multiple battery cells based on the N voltage rising curve segments of each battery cell. Specifically, Fig.10 As shown, a schematic diagram of a process for determining a first reference battery cell in a battery module from a plurality of battery cells in a battery module based on a voltage variation curve of each battery cell is provided, comprising the following steps:

[0179] S1002 : For each battery cell in the battery module, determine a second curve segment from N voltage rising curve segments of the battery cell.

[0180] The voltage of the battery cell at the start of the second curve segment is greater than or equal to the preset voltage, and less than the voltage at the start of the residual voltage rising curve segment of the battery cell. The preset voltage represents the critical voltage of the charging terminal. When the voltage of the battery cell is greater than the preset voltage, it means that the battery cell enters the charging terminal. Therefore, the second curve segment also refers to the first rising curve segment after the battery cell enters the charging terminal.

[0181] Usually, during the charging process, as the charging time goes by, the battery cell will enter the platform area. After the battery cell leaves the platform area and reaches the high-end area, the voltage of the battery cell may show a downward trend due to the change in the charging rate. After dropping to a certain level, the voltage shows an upward trend again, and the cycle continues until the battery cell is charged to the cut-off state. Among them, the state where the battery cell leaves the platform area and reaches the high-end area can be called the charging terminal state, that is, the battery cell enters the charging terminal.

[0182] S1004: Based on the voltages of the plurality of battery cells at the start time of the second curve segments, determine a battery cell with the largest voltage as a first reference battery cell.

[0183] Among them, the cell with the largest voltage at the start time is determined as the first target cell, and the voltage at the start time is greater than the preset voltage, that is, the first reference cell is the cell that first enters the charging terminal among the multiple cells. When the first reference cell first enters the charging terminal, the voltage of the first reference cell in the subsequent charging process is greater than the voltage of other cells. Therefore, after the first reference cell is determined, the first state of charge difference between the first reference cell and other cells in the battery module is the state of charge difference determined from the perspective of the maximum voltage in the battery module.

[0184] based on Fig.10 The method shown determines the second target segment of each battery cell by analyzing N voltage rising curve segments of each battery cell. Thus, based on the second target segment of each battery cell, the first reference battery cell can be determined from the battery module in real time, thereby improving the balancing accuracy.

[0185] In the case where the first reference battery cell is determined from the plurality of battery cells based on the respective second curve segments of the plurality of battery cells, in some embodiments, Fig.11 As shown, a schematic diagram of a process for determining a first state of charge difference between a first reference cell in a battery module and other cells in the battery module based on a voltage change curve of a first reference cell in a battery module is provided, comprising the following steps:

[0186] S1102, determining a third target segment from the N voltage rising curve segments of the first reference battery cell, wherein the charge state difference between two ends of the third target segment is the largest.

[0187] There is no limitation on the method for obtaining the state of charge difference between the two ends of the third target segment. For example, reference may be made to the method for determining the state of charge difference between the two ends of the voltage rising curve segment of the module boundary cells in S602.

[0188] S1104, obtaining a second mapping relationship between a maximum voltage matching the first reference battery cell and a state of charge difference.

[0189] Among them, the first reference cell is the cell that first enters the charging terminal among the multiple cells, and in the subsequent charging process, the voltage of the first reference cell is greater than the voltage of other cells, so the second mapping relationship is a relationship obtained by considering the maximum voltage in the battery module. The second mapping relationship is obtained based on the sub-curve segments obtained after the third curve segment is divided according to the second preset state of charge interval. The implementation method of the second mapping relationship can refer to the method of obtaining the first mapping relationship in the aforementioned S606, which will not be repeated here.

[0190] S1106, for other battery cells in the battery module except the first reference battery cell, based on the second mapping relationship, the charge state difference matched with the voltage of other battery cells in the cut-off state is determined as the first charge state difference between the first reference battery cell in the battery module and other battery cells in the battery module.

[0191] Specifically, the second mapping relationship includes multiple maximum voltages and the charge state difference corresponding to each maximum voltage. Then, from the multiple maximum voltages in the second mapping relationship, the maximum voltage that matches the voltage of other battery cells in the cut-off state is determined; the charge state difference that matches the determined maximum voltage in the second mapping relationship is determined as the first charge state difference between the first reference battery cell and the other battery cells.

[0192] In some embodiments, when there are multiple battery modules, for each battery module, when the first state of charge difference between the first reference battery cell and other battery cells in the battery module is obtained, the battery cell with the largest first state of charge difference is determined as the candidate battery cell, and the balancing time corresponding to the remaining battery cells in the battery module is determined based on the state of charge difference between the candidate battery cell and the remaining battery cells other than the candidate battery cells in the battery module, and the remaining battery cells are balanced based on the balancing time corresponding to the remaining battery cells. The remaining battery cells include the first reference battery cell and other battery cells in the battery module except the candidate battery cell and the first reference battery cell.

[0193] Among them, for the first reference cell in the battery module, the first state of charge difference between the first reference cell and the candidate cell is determined as the state of charge difference between the candidate cell and the first reference cell, and then the state of charge difference between the candidate cell and the first reference cell and the ratio of the first balancing current are determined as the balancing time corresponding to the first reference cell. For other cells in the battery module except the candidate cell and the first reference cell, the balancing time corresponding to the other cells is determined based on the first state of charge difference between the first reference cell and the candidate cell, the balancing time corresponding to the first reference cell, and the first state of charge difference between the first reference cell and the other cells.

[0194] For example, the battery module includes cell a1, cell a2 and cell a3, cell a1 is a candidate cell, cell a3 is a first reference cell, the difference in state of charge between cell a3 and cell a2 is expressed as cell a3 is 1% higher than cell a1, the difference in state of charge between cell a3 and cell a1 is expressed as cell a3 is 2% higher than cell a1, the balancing time corresponding to cell a3 is T1, and the balancing time based on cell a2 is T1 / 2.

[0195] based on Fig.11 The method shown can obtain a second mapping relationship between the maximum voltage matching the first reference battery cell and the state of charge difference based on the third curve segment of the first reference battery cell, and then improve the determination efficiency when determining the first state of charge difference between the first reference battery cell and other battery cells in the battery module based on the second mapping relationship.

[0196] In combination with the above, the battery may include multiple battery modules, such as Fig.12 As shown, a battery balancing method is provided, which is applied to Figure 1 The battery management system 102 in FIG. 1 is taken as an example to illustrate, and the following steps are included:

[0197] S1202, for each battery cell in each battery module, determine a second curve segment from the N voltage rising curve segments of the battery cell, the voltage of the battery cell at the starting moment of the second curve segment is greater than or equal to a preset voltage and less than the voltage of the remaining voltage rising curve segments of the battery cell at the starting moment.

[0198] S1204 , for the multiple battery cells in each battery module, based on the voltages of the multiple battery cells at the start time of the second curve segments, determine the battery cell with the largest voltage as the first reference battery cell in each battery module.

[0199] S1206: for the first reference battery cell in each battery module, determine a third curve segment from the N voltage rising curve segments of the first reference battery cell, wherein the charge state difference between two ends of the third curve segment is the largest.

[0200] S1208, for other battery cells in the battery module except the first reference battery cell, based on the second mapping relationship between the maximum voltage matching the first reference battery cell and the state of charge difference, the state of charge difference that matches the voltage of other battery cells in the cut-off state is determined as the first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module.

[0201] S1210, for any two adjacent battery modules, when the temperature difference between the module boundary cells in the two adjacent battery modules is within a preset range, for each module boundary cell, determine a first curve segment from N voltage rising curve segments of the module boundary cell.

[0202] S1212: From the first curve segments corresponding to the adjacent module boundary cells, determine the module boundary cell with the largest voltage at the start time of the first curve segment as the first boundary cell, and determine the remaining module boundary cells as the second boundary cells.

[0203] S1214, based on the first mapping relationship between the maximum voltage matching the first boundary cell and the state of charge difference, the state of charge difference matching the voltage at the end moment of the first curve segment of the second boundary cell is determined as the boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules.

[0204] S1216, determining a state of charge difference between first reference cells of two adjacent battery modules based on a boundary state of charge difference between two adjacent battery modules and a first state of charge difference corresponding to each cell in two adjacent battery modules.

[0205] S1218, when the state of charge difference between the first reference cells of two adjacent battery modules is determined as the second state of charge difference between the adjacent battery modules, a second reference cell is determined from a plurality of first reference cells based on the state of charge difference between all the first reference cells of two adjacent battery modules.

[0206] S1220, determining a third state of charge difference between a second reference cell and each cell in each battery module based on the first state of charge difference corresponding to each cell in each battery module and the state of charge difference between the first reference cells of all two adjacent battery modules.

[0207] S1222: Determine a third reference battery cell from a plurality of battery cells corresponding to a plurality of battery modules based on a difference in third states of charge corresponding to each battery cell in each battery module.

[0208] S1224: Determine a balancing time corresponding to each battery cell in each battery module based on a fourth state of charge difference between the third reference battery cell and each battery cell in each battery module and the first balancing current.

[0209] S1226, performing balancing processing on each battery cell in each battery module based on the balancing time corresponding to each battery cell in each battery module.

[0210] Among them, the specific content of S1202-S1226 can be adapted to the description of the above content and will not be repeated here.

[0211] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0212] Based on the same inventive concept, the embodiment of the present application also provides a battery balancing device for implementing the battery balancing method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more battery balancing device embodiments provided below can refer to the limitations of the battery balancing method above, and will not be repeated here.

[0213] In one embodiment, Fig.13 As shown, a battery balancing device is provided, including: a first determination module 1302, a second determination module 1304 and a processing module 1306, wherein: the first determination module 1302 is used to obtain the voltage change curve of each battery cell in the battery module when it is charged to the cut-off state, and determine the first reference battery cell in the battery module from the multiple battery cells in the battery module based on the voltage change curve of each battery cell; the second determination module 1304 is used to determine the first charge state difference between the first reference battery cell in the battery module and other battery cells in the battery module based on the voltage change curve of the first reference battery cell in the battery module; the processing module 1306 is used to balance each battery cell in the battery module based on the first charge state difference corresponding to each battery cell in the battery module.

[0214] In one embodiment, there are multiple battery modules; the processing module 1306 is further used to: determine the second state of charge difference between any two adjacent battery modules; and balance each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module.

[0215] In one embodiment, the processing module 1306 is further used to: determine the temperature difference between any two adjacent battery modules; and determine the second state of charge difference between the two adjacent battery modules when the temperature difference is within a preset range.

[0216] In one embodiment, the second state of charge difference between adjacent battery modules includes: a state of charge difference between first reference battery cells of two adjacent battery modules.

[0217] In one embodiment, the processing module 1306 is further used to: determine, for any two adjacent battery modules, a boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules; determine a boundary state of charge difference between the two adjacent battery modules based on the boundary state of charge difference between the two adjacent battery modules and a first state of charge difference corresponding to each cell in the two adjacent battery modules, a first reference state of charge difference between the two adjacent battery modules.

[0218] In one embodiment, the voltage change curve includes N voltage rising curve segments; the processing module 1306 is further used to: for each module boundary cell, determine a first curve segment from the N voltage rising curve segments of the module boundary cell, and the charge state difference between the two ends of the module boundary cell is the largest; from the first curve segments corresponding to the adjacent module boundary cells, determine the module boundary cell with the largest voltage at the starting moment of the first curve segment as the first boundary cell, and determine the remaining module boundary cells as the second boundary cells; determine a first mapping relationship between the maximum voltage matching the first boundary cell and the charge state difference; wherein the first mapping relationship is obtained based on the divided sub-curve segments when the first curve segment of the first boundary cell is divided according to the first preset charge state interval; based on the first mapping relationship, determine the charge state difference matching the voltage at the end moment of the first curve segment of the second boundary cell as the boundary charge state difference between the adjacent module boundary cells of the two adjacent battery modules.

[0219] In one embodiment, the processing module 1306 is further used to: determine a second reference cell from multiple first reference cells based on the difference in state of charge between the first reference cells of all two adjacent battery modules; determine a third state of charge difference between the second reference cell and each cell in each battery module based on the difference in the first state of charge corresponding to each cell in each battery module and the difference in the state of charge between the first reference cells of all two adjacent battery modules; determine a third reference cell from multiple cells corresponding to multiple battery modules based on the difference in the third state of charge corresponding to each cell in each battery module; determine the balancing time corresponding to each cell in each battery module based on the difference in the fourth state of charge between the third reference cell and each cell in each battery module and the first balancing current; and balance each cell in each battery module based on the balancing time corresponding to each cell in each battery module.

[0220] In one embodiment, the processing module 1306 is further used to: determine the state of charge mean between the multiple battery cells in each of two adjacent battery modules; and determine the second state of charge difference between the two adjacent battery modules based on the state of charge difference between the state of charge means of the two adjacent battery modules.

[0221] In one embodiment, the second state of charge difference between two adjacent battery modules includes the state of charge difference between the state of charge means of the two adjacent battery modules; the processing module 1306 is also used to: determine a target battery module from multiple battery modules based on the state of charge difference between the state of charge means of all adjacent battery modules; the state of charge mean of the target battery module is the smallest; for other battery modules among the multiple battery modules except the target battery module, based on the fifth state of charge difference between the target battery module and the other battery modules, balance the battery cells in the other battery modules.

[0222] In one embodiment, the voltage change curve includes N voltage rising curve segments; the first determination module 1302 is further used to: for each battery cell in the battery module, determine a second curve segment from the N voltage rising curve segments of the battery cell; wherein the voltage of the battery cell at the starting moment of the second curve segment is greater than or equal to a preset voltage, and is less than the voltage of the remaining voltage rising curve segments of the battery cell at the starting moment; based on the voltages of the second curve segments of each of the multiple battery cells at the starting moment, determine the battery cell with the largest voltage as the first reference battery cell.

[0223] In one embodiment, the second determination module 1304 is also used to: determine a third curve segment from the N voltage rising curve segments of the first reference battery cell, where the state of charge difference between the two ends of the third curve segment is the largest; obtain a second mapping relationship between the maximum voltage matching the first reference battery cell and the state of charge difference; wherein the second mapping relationship is obtained based on the sub-curve segments obtained after dividing the third curve segment according to a second preset state of charge interval; for other battery cells in the battery module except the first reference battery cell, based on the second mapping relationship, determine the state of charge difference that matches the voltage of other battery cells in the cut-off state as the first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module.

[0224] Each module in the above-mentioned battery balancing device can be implemented in whole or in part by software, hardware or a combination thereof. Each of the above-mentioned modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0225] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Fig.14 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data such as the first charge state difference between the first reference battery cell in the battery module and the other batteries in the battery module. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a battery balancing method is implemented.

[0226] Those skilled in the art will understand that Fig.14 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0227] In one embodiment, a computer device is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiments when executing the computer program.

[0228] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0229] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0230] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0231] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0232] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A battery balancing method, characterized in that: The method comprises: Obtaining a voltage variation curve of each battery cell in the battery module when it is charged to a cut-off state, wherein the voltage variation curve includes N voltage rising curve segments; For each battery cell in the battery module, a second curve segment is determined from the N voltage rising curve segments of the battery cell; wherein the voltage of the battery cell at the start time of the second curve segment is greater than or equal to a preset voltage and less than the voltage of the remaining voltage rising curve segments of the battery cell at the start time; Based on the voltages of the respective second curve segments of the plurality of battery cells at the start time, determining the battery cell with the largest voltage as the first reference battery cell in the battery module; Determining a first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module based on a voltage change curve of the first reference battery cell in the battery module; In the case where there are multiple battery modules, for any two adjacent battery modules, determining a second state of charge difference between the two adjacent battery modules; Based on the second state of charge differences between all adjacent battery modules and the first state of charge differences corresponding to the battery cells in each of the battery modules, each of the battery cells in each of the battery modules is subjected to balancing processing.

2. The method according to claim 1, characterized in that The step of determining, for any two adjacent battery modules, a second state of charge difference between the two adjacent battery modules includes: For any two adjacent battery modules, determine the temperature difference between the two adjacent battery modules; When the temperature difference is within a preset range, a second state of charge difference between two adjacent battery modules is determined.

3. The method according to claim 2, characterized in that The second charge state difference between adjacent battery modules includes: the charge state difference between first reference battery cells of two adjacent battery modules.

4. The method according to claim 3, characterized in that The method for determining the difference in state of charge between the first reference cells of the two adjacent battery modules includes: For any two adjacent battery modules, determining the boundary state of charge difference between the adjacent module boundary cells of the two adjacent battery modules; Based on the boundary state of charge difference between two adjacent battery modules and the first state of charge difference corresponding to each battery cell in the two adjacent battery modules, the state of charge difference between the first reference battery cells of the two adjacent battery modules is determined.

5. The method according to claim 4, characterized in that The voltage variation curve includes N voltage rising curve segments; and the step of determining the boundary state of charge difference between the boundary cells of two adjacent battery modules includes: For each module boundary cell, determine a first curve segment from the N voltage rising curve segments of the module boundary cell, where the difference in state of charge of the module boundary cell between two ends of the first curve segment is the largest; From the first curve segments corresponding to the adjacent module boundary cells, the module boundary cell having the largest voltage at the start time of the first curve segment is determined as the first boundary cell, and the remaining module boundary cells are determined as the second boundary cells; Determine a first mapping relationship between a maximum voltage matching the first boundary cell and a state of charge difference; wherein the first mapping relationship is obtained based on the divided sub-curve segments when the first curve segment of the first boundary cell is divided according to a first preset state of charge interval; Based on the first mapping relationship, the state of charge difference that matches the voltage at the end moment of the first curve segment of the second boundary cell is determined as the boundary state of charge difference between adjacent module boundary cells of two adjacent battery modules.

6. The method according to claim 4, characterized in that The balancing process of each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module includes: Determining a second reference cell from a plurality of first reference cells based on a difference in the states of charge between the first reference cells of all two adjacent battery modules; Determine a third state of charge difference between the second reference cell and each cell in each battery module based on the first state of charge difference corresponding to each cell in each battery module and the state of charge difference between the first reference cells of all two adjacent battery modules; Determining a third reference battery cell from a plurality of battery cells corresponding to a plurality of battery modules based on a difference in the third state of charge corresponding to each battery cell in each of the battery modules; Determining a balancing time corresponding to each battery cell in each battery module based on a fourth state of charge difference between the third reference battery cell and each battery cell in each battery module, and the first balancing current; Based on the balancing time corresponding to each battery cell in each battery module, balancing processing is performed on each battery cell in each battery module.

7. The method according to claim 2, characterized in that The determining of a second state of charge difference between two adjacent battery modules includes: Determine a mean state of charge between a plurality of battery cells in two adjacent battery modules; Based on the state of charge difference between the state of charge averages of the two adjacent battery modules, a second state of charge difference between the two adjacent battery modules is determined.

8. The method according to claim 7, characterized in that The second state of charge difference between the two adjacent battery modules includes a state of charge difference between the state of charge means of the two adjacent battery modules; The balancing process of each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module includes: Determining a target battery module from a plurality of battery modules based on a state of charge difference between the state of charge mean values ​​of all adjacent battery modules; the state of charge mean value of the target battery module being the smallest; For other battery modules except the target battery module among the plurality of battery modules, balancing processing is performed on each battery cell in the other battery modules based on a fifth state of charge difference between the target battery module and the other battery modules.

9. The method according to claim 1, characterized in that: The determining, based on the voltage change curve of the first reference battery cell in the battery module, a first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module comprises: Determine a third curve segment from the N voltage rising curve segments of the first reference battery cell, wherein the charge state difference between two ends of the third curve segment is the largest; Obtaining a second mapping relationship between a maximum voltage matching the first reference battery cell and a state of charge difference; wherein the second mapping relationship is obtained based on sub-curve segments obtained after the third curve segment is divided according to a second preset state of charge interval; For other battery cells in the battery module except the first reference battery cell, based on the second mapping relationship, the charge state difference that matches the voltage of the other battery cells in the cut-off state is determined as the first charge state difference between the first reference battery cell in the battery module and the other battery cells in the battery module.

10. A battery balancing device, characterized in that: The device comprises: A first determination module is used to obtain a voltage change curve of each battery cell in the battery module when it is charged to a cut-off state, wherein the voltage change curve includes N voltage rising curve segments; for each battery cell in the battery module, a second curve segment is determined from the N voltage rising curve segments of the battery cell; wherein the voltage of the battery cell at the start time of the second curve segment is greater than or equal to a preset voltage and less than the voltage at the start time of the remaining voltage rising curve segment of the battery cell; based on the voltages at the start time of the second curve segments of each of the plurality of battery cells, the battery cell with the largest voltage is determined as the first reference battery cell in the battery module; a second determination module, configured to determine a first state of charge difference between the first reference battery cell in the battery module and other battery cells in the battery module based on a voltage change curve of the first reference battery cell in the battery module; A processing module is used to determine, for any two adjacent battery modules, a second state of charge difference between two adjacent battery modules when there are multiple battery modules; and to balance each battery cell in each battery module based on the second state of charge difference between all adjacent battery modules and the first state of charge difference corresponding to each battery cell in each battery module.

11. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 9 are implemented.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

13. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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