A battery balancing method, system, device and medium suitable for improving the capacity utilization rate of battery packs in energy storage systems

Abstract

The present invention belongs to the field of energy storage battery management technology, and specifically relates to a battery balancing method, system, device and medium suitable for improving the capacity utilization rate of a battery pack of an energy storage system, including obtaining a data set of charging and discharging conditions of a battery pack within a set period, and dynamic OCV data, determining the cell with the smallest capacity and using it as a reference cell; when the temperature and current conditions of the battery pack of the charging and discharging condition data set and the dynamic OCV data are consistent, fitting the voltage data of each cell to obtain the SOC of each cell in the battery pack; starting the battery balancing according to the relationship between the difference between the reference cell SOC and the other cell SOCs during the charging and discharging process and the preset first difference threshold and second difference threshold. The balancing method proposed in the present invention finds the cell with the smallest capacity in the battery pack, and balances the battery pack based on the cell, ensuring that the first cells to be filled and the first cells to be discharged during charging and discharging are the cells with the smallest capacity, thereby maximizing the capacity utilization rate of the battery pack.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage battery management, and specifically relates to a battery balancing method, system, device and medium suitable for improving the capacity utilization rate of battery packs in energy storage systems. Background Art

[0002] In practical applications, battery packs are usually balanced to improve the consistency between cells within a battery pack. The goals of existing battery pack balancing strategies usually include voltage consistency, SOC consistency, and capacity consistency. However, the above balancing methods have the following problems:

[0003] 1. The basic principle of voltage consistency is to determine whether balancing is required by comparing the voltage difference between each cell with a preset voltage threshold. While it is easy to use voltage consistency as a balancing target, voltage is an external parameter of the battery and is easily affected by external and internal factors, which does not maximize the utilization of the battery pack capacity.

[0004] 2. Balancing based on SOC consistency requires estimating the battery SOC and using a suitable circuit topology to ensure that the SOC difference of each cell is within a certain range. This method is suitable for battery packs with small differences in cell capacity and can fully utilize the battery pack capacity. However, the balancing effect is limited for battery packs with certain differences in cell capacity.

[0005] 3. The balancing target based on capacity consistency can be divided into two types: based on the consistency of the remaining charging capacity and based on the consistency of the remaining discharging capacity. The principles are similar, but the key is that there is a certain degree of difficulty in estimating the capacity, so it is less used. Summary of the Invention

[0006] The purpose of the present invention is to provide a battery balancing method, system, device and medium suitable for improving the capacity utilization of battery packs in energy storage systems, so as to solve the problems raised in the background technology.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0008] In a first aspect, the present invention provides a battery balancing method suitable for improving the capacity utilization rate of a battery pack in an energy storage system, the method comprising:

[0009] Obtain the battery pack's charge and discharge condition data set and dynamic OCV data within a set period, and determine whether there is a cell with the smallest capacity in the battery pack based on the set determination conditions and the condition data set. If so, use the cell with the smallest capacity as the reference cell;

[0010] When the battery pack temperature and current conditions of the charge and discharge condition data set are consistent with those of the dynamic OCV data, the voltage data of each cell is fitted to obtain the SOC of each cell in the battery pack;

[0011] Initiate cell balancing based on the relationship between the difference between the reference cell SOC and the other cell SOCs and the preset first difference threshold and second difference threshold during charging and discharging;

[0012] The determination condition is that when the rank of a cell in the highest or lowest voltage cell numbering sequence and the frequency of occurrence of the same rank are both within a set range, the cell is determined to be the cell with the smallest capacity.

[0013] As a further optimization solution of the present invention, the operating condition data set includes the highest cell voltage, the lowest cell voltage, the highest voltage cell number and the lowest voltage cell number.

[0014] As a further optimization solution of the present invention, when the charge and discharge condition data set is consistent with the battery pack temperature and current conditions of the dynamic OCV data, fitting the voltage data of each cell to obtain the SOC of each cell in the battery pack includes:

[0015] During the process of acquiring the charge and discharge operating condition data set, when the battery pack temperature and current conditions are consistent with the temperature and current conditions for acquiring the dynamic OCV data, the voltage data of each cell is input into the fitted function relationship to calculate the SOC of each cell, as shown in the following formula:

[0016] SOC=k0·OCV 7 +k1·OCV 6 +k2·OCV 5 +k3·OCV 4 +k4·OCV 3 +k5·OCV 2 +k6·OCV+k7

[0017] In the above formula, k0 to k7 are coefficients of the functional relationship; OCV is the dynamic OCV data, that is, the single-cell operating voltage.

[0018] As a further optimization solution of the present invention, the method of starting cell balancing according to the relationship between the difference between the reference cell SOC and the other cell SOCs and a preset first difference threshold ΔSOC1 during the charge and discharge process includes:

[0019] Under charging conditions, when there are other cells with SOC greater than the reference cell SOC and the difference between the two is greater than or equal to the first difference threshold ΔSOC1, balancing is turned on and cells with SOC greater than the reference cell SOC are balanced and discharged separately. Balancing is turned off when the target balancing time is reached;

[0020] The calculation method for the target equilibrium time of each monomer is as follows:

[0021]

[0022] In the above formula, T i is the equilibrium time of the ith balanced monomer; SOC i is the SOC of the ith balanced monomer; SOC s is the SOC of the benchmark monomer; C e is the nominal capacity of the battery pack; δ is the capacity temperature coefficient; I is the balancing current.

[0023] As a further optimization solution of the present invention, the method of initiating cell balancing according to the relationship between the difference between the reference cell SOC and the other cell SOCs and a preset first difference threshold during charging and discharging also includes:

[0024] Under the discharge condition, when the SOC of other cells is lower than the SOC of the reference cell and the difference between the two is greater than or equal to the second difference threshold ΔSOC2, balancing is turned on to balance the discharge of the reference cell. When the target balancing time is reached, balancing is turned off.

[0025] The calculation method of the benchmark single target equilibrium time is as follows:

[0026]

[0027] In the above formula, T s is the equilibrium time of the benchmark monomer; SOC min The lowest single SOC; SOC s is the SOC of the benchmark monomer; C e is the nominal capacity of the battery pack; δ is the capacity temperature coefficient; I is the balancing current.

[0028] As a further optimization solution of the present invention, the determining whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the operating condition data set further includes:

[0029] If it does not exist, the SOC difference between each cell in the battery pack and the lowest cell SOC is determined, and cell balancing is initiated based on the relationship between the SOC difference during the charge and discharge process and the preset third difference threshold ΔSOC3. The target balancing time for each cell is calculated as follows:

[0030]

[0031] In the above formula, T i is the equilibrium time of the i-th balanced monomer; ΔSOC i is the SOC difference between the ith balanced cell and the lowest cell; C e is the nominal capacity of the battery pack; δ is the capacity temperature coefficient; I is the balancing current.

[0032] As a further optimization solution of the present invention, the first difference threshold ΔSOC1 , the second difference threshold ΔSOC2 , and the third difference threshold ΔSOC3 are all set to 2%.

[0033] In a second aspect, the present invention provides a battery balancing system suitable for improving the capacity utilization rate of a battery pack in an energy storage system, the system comprising:

[0034] The first determination module is configured to obtain a data set of charge and discharge operating conditions of the battery pack within a set period, and dynamic OCV data, and determine whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the operating condition data set. If so, the cell with the smallest capacity is used as a reference cell;

[0035] A fitting module is used to fit the voltage data of each cell to obtain the SOC of each cell in the battery pack when the charge and discharge condition data set is consistent with the battery pack temperature and current conditions of the dynamic OCV data;

[0036] A first balancing module is configured to start cell balancing according to a relationship between a difference between a reference cell SOC and the SOCs of other cells and a preset first difference threshold and a second difference threshold during charging and discharging;

[0037] The determination condition is that when the rank of a cell in the highest or lowest voltage cell numbering sequence and the frequency of occurrence of the same rank are both within a set range, the cell is determined to be the cell with the smallest capacity.

[0038] As a further optimization solution of the present invention, the system further includes:

[0039] A second determination module is configured to determine whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the operating condition data set, and if not, determine the SOC difference between the SOC of each cell in the battery pack and the SOC of the lowest cell;

[0040] The second balancing module is configured to start battery balancing according to a relationship between an SOC difference and a preset third difference threshold value during the charging and discharging process.

[0041] In a third aspect, the present invention further provides an electronic device, comprising a memory module, and a logic operation control program stored in the memory module and executable by the processor module, wherein the processor module implements any of the above-described battery balancing methods when executing the logic operation control program.

[0042] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements any of the above battery balancing methods when executed by a processor module.

[0043] The beneficial effects of the present invention are:

[0044] The balancing method proposed in the present invention finds the cell with approximately the smallest capacity in the battery pack and performs balancing management on the battery pack based on the cell, ensuring that the cells that are first filled to capacity and first discharged during charging and discharging are cells with approximately the smallest capacity, thereby maximizing the capacity utilization of the battery pack, extending the service life of the battery pack and slowing down aging. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A flow chart of a battery balancing method for improving the capacity utilization of battery packs in an energy storage system proposed by the present invention;

[0046] Figure 2 The present invention provides a system framework diagram of a battery balancing system suitable for improving the capacity utilization rate of battery packs in energy storage systems;

[0047] Figure 3 Schematic diagram of battery pack inconsistency in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0049] Example 1

[0050] Based on the existing technology, the inconsistency of battery cells will greatly affect the utilization rate of the battery pack. Figure 3 , which shows a schematic diagram of battery pack inconsistency in the prior art. Assuming that the series battery pack contains three cells B1, B2, and B3, among which B2 has the smallest capacity, the figure shows several situations where capacity inconsistency and SOC inconsistency between cells are superimposed. Due to the existence of the battery pack's "barrel effect", these situations will produce different battery pack utilization rates during charging and discharging, as shown below:

[0051] In Figure (a), when charging, the first cell to be fully charged is the cell B2 with the smallest capacity. When discharging, the first cell to be fully discharged is also the cell B2 with the smallest capacity. That is, the first cell to be fully charged and the first cell to be fully discharged are both the cells with the smallest capacity. At this time, the available capacity AC of the battery pack is the capacity of the cell with the smallest capacity.

[0052] In Figure (b), when charging, the first cell to be fully charged is cell B3, and when discharging, the first cell to be fully discharged is cell B1. That is, the first cell to be fully charged and the first cell to be fully discharged are not the cells with the smallest capacity. At this point, the figure shows that the available capacity AC of the battery pack is even smaller than the capacity of cell B2.

[0053] In Figure (c), when charging, cells B1 and B3 are the first to be fully charged. When discharging, cell B2 is the first to be fully discharged. That is, the cell with the smallest capacity is not the first to be fully charged, but the first to be fully discharged. At this time, it can be seen from the figure that the available capacity AC of the battery pack is less than the capacity of cell B2.

[0054] In Figure (d), when charging, the first cell to be fully charged is cell B2, and when discharging, the first cells to be fully discharged are B1 and B3. That is, the cell with the smallest capacity is fully charged first, and the cell with the smallest capacity is not the first to be fully discharged. At this time, it can be seen from the figure that the available capacity AC of the battery pack is less than the capacity of cell B2.

[0055] Therefore, in theory, the maximum utilization capacity that a battery pack can achieve is the capacity of the smallest cell in the battery pack. That is, when the cells that are first filled and discharged during charging and discharging are both the cells with the smallest capacity, the battery pack capacity utilization rate reaches its maximum.

[0056] In summary, to maximize the utilization of battery pack capacity, it is necessary to ensure that the cells that are first fully charged and first fully discharged during charging and discharging are the cells with the smallest capacity, such as Figure 1 As shown, this embodiment proposes a battery balancing method suitable for improving the capacity utilization rate of the battery pack of the energy storage system, and the method includes:

[0057] Obtain the battery pack's charge and discharge condition data set and dynamic OCV data within a set period, and determine whether there is a cell with the smallest capacity in the battery pack based on the set determination conditions and the condition data set. If so, use the cell with the smallest capacity as the reference cell;

[0058] When the battery pack temperature and current conditions of the charge and discharge condition data set are consistent with those of the dynamic OCV data, the voltage data of each cell is fitted to obtain the SOC of each cell in the battery pack;

[0059] Initiate cell balancing based on the relationship between the difference between the reference cell SOC and the other cell SOCs and the preset first difference threshold and second difference threshold during charging and discharging;

[0060] The determination condition is that when the position of a certain cell in the highest or lowest voltage cell numbering sequence and the frequency of occurrence of the same position are both within a set range, the cell is determined to be the cell with the smallest capacity.

[0061] In this embodiment, actual charge and discharge operating condition data of the battery pack within a certain period of time (such as one week) is periodically collected and acquired. The operating condition data set includes the highest cell voltage, the lowest cell voltage, the highest voltage cell number, and the lowest voltage cell number.

[0062] As an example, in this embodiment, based on the determination conditions and the operating condition data set, the cell with the approximately minimum capacity in the battery pack within the cycle is determined by statistical calculation as follows:

[0063] The rank and frequency of the cell number with the highest cell voltage appearing in the charging data, as well as the cell number with the lowest cell voltage appearing in the discharge data within the time period are statistically calculated, and the cell numbers are sorted in descending order by frequency respectively. Based on the statistical results, the method for determining the cell with the smallest capacity is as follows: if a cell ranks (ranks) in the top 3 (including the 3rd) positions in both the highest voltage cell number sorting and the lowest voltage cell number sorting, and the frequencies are both greater than or equal to 0.3, then the cell is determined to be the cell with approximately the smallest capacity.

[0064] The statistical results are shown in Table 1:

[0065]

[0066]

[0067] Table 1

[0068] From the results in Table 1, it can be seen that in the current time period, the No. 1 cell of the battery pack is the cell with the smallest capacity, and is set as the above-mentioned reference cell.

[0069] In this embodiment, when the charge and discharge condition data set is consistent with the battery pack temperature and current conditions of the dynamic OCV data, the voltage data of each cell is fitted to obtain the SOC of each cell in the battery pack, including:

[0070] During the charge and discharge process of acquiring the working condition data set, when the battery pack temperature and current conditions are consistent with the temperature and current conditions for acquiring the dynamic OCV data, the voltage data of each cell is input into the fitted function relationship to calculate the SOC of each cell, as shown in the following formula:

[0071] SOC=k0·OCV 7 +k1·OCV 6 +k2·OCV 5 +k3·OCV 4 +k4·OCV 3 +k5·OCV 2 +k6·OCV+k7

[0072] In the above formula, k0 to k7 are coefficients of the functional relationship; OCV is the dynamic OCV data, that is, the single-cell operating voltage.

[0073] It is understandable that dynamic OCV data is mainly obtained through test experiments. Since the charging and discharging conditions of energy storage systems are generally relatively simple and fixed, charge and discharge tests are carried out in advance using temperature and current conditions consistent with future actual operating conditions to obtain two-dimensional data of single-cell operating voltage and SOC, namely dynamic OCV data. Based on this data, the above-mentioned high-order polynomial method is used to fit the functional relationship between the two.

[0074] In this embodiment, cell balancing is initiated based on the relationship between the difference between the reference cell SOC and the other cell SOCs and a preset first difference threshold ΔSOC1 during the charge and discharge process, including:

[0075] (1) Under charging conditions, when there are other cells with SOC greater than the reference cell SOC and the difference between the two is greater than or equal to the first difference threshold ΔSOC1, balancing is turned on and the cells with SOC greater than the reference cell SOC are discharged for balancing. When the target balancing time is reached, balancing is turned off. The first difference threshold ΔSOC1 can be 2%;

[0076] The calculation method for the target equilibrium time of each monomer is as follows:

[0077]

[0078] In the above formula, T i is the equilibrium time of the ith balanced monomer; SOC i is the SOC of the ith balanced monomer; SOC s is the SOC of the benchmark monomer; C e is the nominal capacity of the battery pack; δ is the capacity temperature coefficient; I is the balancing current.

[0079] In this embodiment, cell balancing is initiated according to the relationship between the difference between the reference cell SOC and the other cell SOCs and a preset first difference threshold value during the charge and discharge process, further comprising:

[0080] (2) Under the discharge condition, when there are other cells with SOC lower than the reference cell SOC and the difference between the two is greater than or equal to the second difference threshold ΔSOC2, the balancing is turned on and the reference cell is discharged evenly. When the target balancing time is reached, the balancing is turned off. The second difference threshold ΔSOC2 can be set to 2%;

[0081] The calculation method of the benchmark single target equilibrium time is as follows:

[0082]

[0083] In the above formula, T s is the equilibrium time of the benchmark monomer; SOC min The lowest single SOC; SOC s is the SOC of the benchmark monomer; C e is the nominal capacity of the battery pack; δ is the capacity temperature coefficient; I is the balancing current.

[0084] In this embodiment, determining whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the operating condition data set further includes:

[0085] If no cell with approximately the smallest capacity exists, it indicates that no cell with approximately the smallest capacity has been found. The SOC difference between each cell in the battery pack and the lowest cell SOC is determined. Cell balancing is initiated based on the relationship between the SOC difference during charge and discharge and a preset third difference threshold ΔSOC3. The third difference threshold ΔSOC3 can be 2%. The target balancing time for each cell is calculated as follows:

[0086]

[0087] In the above formula, T i is the equilibrium time of the i-th balanced monomer; ΔSOC i is the SOC difference between the ith balanced cell and the lowest cell; C e is the nominal capacity of the battery pack; δ is the capacity temperature coefficient; I is the balancing current.

[0088] like Figure 2 As shown, based on the same inventive concept, this embodiment also proposes a battery balancing system suitable for improving the capacity utilization rate of the battery pack of the energy storage system, the system comprising:

[0089] The first determination module is configured to obtain a data set of charge and discharge operating conditions of the battery pack within a set period, and dynamic OCV data, and determine whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the operating condition data set. If so, the cell with the smallest capacity is used as a reference cell;

[0090] A fitting module is used to fit the voltage data of each cell to obtain the SOC of each cell in the battery pack when the charge and discharge condition data set is consistent with the battery pack temperature and current conditions of the dynamic OCV data;

[0091] A first balancing module is configured to start cell balancing according to a relationship between a difference between a reference cell SOC and the SOCs of other cells and a preset first difference threshold and a second difference threshold during charging and discharging;

[0092] The determination condition is that when the position of a certain cell in the highest or lowest voltage cell numbering sequence and the frequency of occurrence of the same position are both within a set range, the cell is determined to be the cell with the smallest capacity.

[0093] Furthermore, the system also includes:

[0094] A second determination module is configured to determine whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the operating condition data set, and if not, determine the SOC difference between the SOC of each cell in the battery pack and the SOC of the lowest cell;

[0095] The second balancing module is configured to start battery balancing according to a relationship between an SOC difference and a preset third difference threshold value during the charging and discharging process.

[0096] This embodiment further proposes an electronic device, including a memory module and a logic operation control program stored in the memory module and executable on a processor module. The processor module implements the above battery balancing method when executing the logic operation control program.

[0097] This embodiment further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by the processor module, the above battery balancing method is implemented.

[0098] According to an embodiment of the present invention, the existing battery balancing method that uses capacity consistency as the balancing goal is rarely used because it is difficult to estimate the cell capacity. The present invention finds the cell with the approximately smallest capacity in the battery pack and balances the battery pack based on this cell, ensuring that the cells that are filled up first and discharged first during charging and discharging are the cells with the approximately smallest capacity, thereby maximizing the capacity utilization of the battery pack.

[0099] In this embodiment, after cell balancing is enabled, the cells that are first fully charged and first fully discharged during the charge and discharge process of the battery pack are ensured to be the cells with the smallest capacity, thereby maximizing the capacity utilization of the battery pack. Improving the capacity utilization is the most critical goal of energy storage system balancing management.

[0100] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters and thresholds in the formulas are set by technicians in this field according to actual conditions.

[0101] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0102] In addition, the functional modules in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0103] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0104] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery balancing method suitable for improving the capacity utilization rate of a battery pack in an energy storage system, characterized in that: The method comprises: Obtain the charging and discharging condition data set and dynamic OCV data of the battery pack within a set period, and determine whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the condition data set. If so, use the cell with the smallest capacity as the reference cell; When the battery pack temperature and current conditions of the charge and discharge condition data set are consistent with those of the dynamic OCV data, the voltage data of each cell is fitted to obtain the SOC of each cell in the battery pack; Initiate battery balancing according to the relationship between the difference between the reference cell SOC and the other cell SOCs and the preset first difference threshold and second difference threshold during the charge and discharge process; The determination condition is that when the rank of a certain cell in the highest or lowest voltage cell numbering sequence and the frequency of occurrence of the same rank are both within a set interval, the cell is determined to be the cell with the smallest capacity; The difference between the reference cell SOC and other cell SOCs during the charging and discharging process and a preset first difference threshold To start battery balancing, we need to use the following relationships: Under charging conditions, when there are other cells with SOC greater than the reference cell SOC and the difference between the two is greater than or equal to the first difference threshold When the target balancing time is reached, the balancing is turned on, and the monomers whose SOC is greater than the reference monomer SOC are discharged in a balanced manner. When the target balancing time is reached, the balancing is turned off. The calculation method of each monomer target equilibrium time is as follows: ； In the above formula, For the The equilibrium time of each balanced cell; For the The SOC of the balanced monomer; is the SOC of the benchmark monomer; is the nominal capacity of the battery pack; is the capacity temperature coefficient; is the balancing current; The method of starting battery balancing according to the relationship between the difference between the reference cell SOC and the other cell SOCs during the charging and discharging process and a preset second difference threshold value also includes: Under discharge conditions, when there are other cells with SOC lower than the reference cell SOC and the difference between the two is greater than or equal to the second difference threshold When the target balancing time is reached, the balancing is turned on to discharge the reference monomer evenly. When the target balancing time is reached, the balancing is turned off. The calculation method of the benchmark monomer target equilibrium time is as follows: ； In the above formula, is the equilibrium time of the benchmark monomer; is the lowest single-unit SOC; is the SOC of the benchmark monomer; is the nominal capacity of the battery pack; is the capacity temperature coefficient; For balancing current.

2. A battery balancing method for improving the capacity utilization of a battery pack in an energy storage system according to claim 1, characterized in that: The operating condition data set includes the highest cell voltage, the lowest cell voltage, the highest voltage cell number and the lowest voltage cell number.

3. A battery balancing method for improving the capacity utilization of a battery pack in an energy storage system according to claim 1, characterized in that: When the charge and discharge condition data set is consistent with the battery pack temperature and current conditions of the dynamic OCV data, each cell voltage data is fitted to obtain the SOC of each cell in the battery pack, including: In the process of acquiring the working condition data set during charge and discharge, when the temperature and current conditions of the battery pack are consistent with the temperature and current conditions for acquiring the dynamic OCV data, the voltage data of each cell is input into the fitted function relationship to calculate the SOC of each cell, as shown in the following formula: ； In the above formula, to is the coefficient of the functional relationship; For dynamic Data, that is, the single-cell operating voltage.

4. A battery balancing method for improving the capacity utilization rate of a battery pack in an energy storage system according to claim 3, characterized in that: The step of determining whether there is a cell with the smallest capacity in the battery pack according to the set determination condition and the operating condition data set also includes: If it does not exist, determine the SOC difference between each cell SOC in the battery pack and the lowest cell SOC, and calculate the SOC difference between the SOC difference during charging and discharging and the preset third difference threshold value. The relationship between the two is used to start battery balancing. The target balancing time of each cell is calculated as follows: ； In the above formula, For the The equilibrium time of each balanced cell; For the The SOC difference between the balanced cell and the lowest cell; is the nominal capacity of the battery pack; is the capacity temperature coefficient; For balancing current.

5. A battery balancing method for improving the capacity utilization of a battery pack in an energy storage system according to claim 4, characterized in that: The first difference threshold , the second difference threshold and the third difference threshold Both are set to 2%.

6. A battery balancing system suitable for improving the capacity utilization rate of a battery pack in an energy storage system, characterized in that: The system comprises: The first determination module is used to obtain a data set of charge and discharge working conditions of the battery pack within a set period, and dynamic OCV data, and determine whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the working condition data set. If so, the cell with the smallest capacity is used as a reference cell; A fitting module is used to fit the voltage data of each cell to obtain the SOC of each cell in the battery pack when the battery pack temperature and current conditions of the charge and discharge condition data set are consistent with those of the dynamic OCV data; A first balancing module, used to start battery balancing according to the relationship between the difference between the reference cell SOC and the other cell SOCs and the preset first difference threshold and second difference threshold during charging and discharging; The determination condition is that when the rank of a certain cell in the highest or lowest voltage cell numbering sequence and the frequency of occurrence of the same rank are both within a set interval, the cell is determined to be the cell with the smallest capacity; In the first balancing module, the difference between the reference cell SOC and other cell SOCs during charging and discharging and a preset first difference threshold To start battery balancing, we need to use the following relationships: Under charging conditions, when there are other cells with SOC greater than the reference cell SOC and the difference between the two is greater than or equal to the first difference threshold When the target balancing time is reached, the balancing is turned on, and the monomers whose SOC is greater than the reference monomer SOC are discharged in a balanced manner. When the target balancing time is reached, the balancing is turned off. The calculation method of each monomer target equilibrium time is as follows: ； In the above formula, For the The equilibrium time of each balanced cell; For the The SOC of the balanced monomer; is the SOC of the benchmark monomer; is the nominal capacity of the battery pack; is the capacity temperature coefficient; is the balancing current; In the first balancing module, the battery balancing is started according to the relationship between the difference between the reference cell SOC and the other cell SOCs during the charging and discharging process and the preset second difference threshold, and further includes: Under discharge conditions, when there are other cells with SOC lower than the reference cell SOC and the difference between the two is greater than or equal to the second difference threshold When the target balancing time is reached, the balancing is turned on to discharge the reference monomer evenly. When the target balancing time is reached, the balancing is turned off. The calculation method of the benchmark monomer target equilibrium time is as follows: ； In the above formula, is the equilibrium time of the benchmark monomer; is the lowest single-unit SOC; is the SOC of the benchmark monomer; is the nominal capacity of the battery pack; is the capacity temperature coefficient; For balancing current.

7. A battery balancing system for improving the capacity utilization of a battery pack in an energy storage system according to claim 6, characterized in that: The system further comprises: A second determination module is used to determine whether there is a cell with the smallest capacity in the battery pack according to the set determination conditions and the operating condition data set, and if not, determine the SOC difference between the SOC of each cell in the battery pack and the SOC of the lowest cell; The second balancing module is used to start battery balancing according to the relationship between the SOC difference and a preset third difference threshold value during the charging and discharging process.

8. An electronic device, characterized in that: The invention comprises a memory module and a processor module, and a logic operation control program stored in the memory module and executable on the processor module. When the processor module executes the logic operation control program, the battery balancing method according to any one of claims 1 to 5 is implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor module, the battery balancing method according to any one of claims 1 to 5 is implemented.

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