Battery system and SOH value determination method, device and storage medium thereof

Abstract

The present invention discloses a battery system and a method, device and storage medium for determining the SOH value thereof. The method for determining the SOH value of the battery system includes: obtaining a first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell, and obtaining a second initial window upper limit value of the reference cell according to the charging cut-off voltage of the target cell; when it is determined that the SOC change value of the reference cell within a preset time is greater than or equal to the first preset value, obtaining the charge and discharge current and SOC change value of the reference cell within the preset time, and determining the SOH value of the target cell according to the initial capacity value, charge and discharge current, SOC change value, preset time, first initial window upper limit value and second initial window upper limit value of the reference cell. The method establishes a window mapping relationship between the reference cell and the target cell, and uses the SOC of the reference cell to participate in calculating the SOH value of the target cell, thereby improving the SOC estimation accuracy of the target cell in the platform area and reducing the accumulated error during long-term use.

Description

Technical Field

[0001] The present invention relates to the technical field of battery systems, and in particular to a battery system and a method, device and storage medium for determining a SOH value thereof. Background Art

[0002] The battery's state of health SOH (State of Health) generally refers to the current capacity retention rate of the power battery, which is the ratio of the current battery pack capacity to the battery pack capacity at the initial BOL (Begin of Life) state, and is an important parameter reflecting the battery life. At the same time, based on the current SOH value, the BMS (Battery Management System) needs to adjust the charging strategy and battery power control strategy. It is a core parameter for power battery system control, so its accuracy is very high. The current SOH estimation method is generally based on the battery throughput (battery charge and discharge cumulative energy) calendar life combined with dynamic SOH correction.

[0003] In the related art, when calculating the SOH of a lithium iron phosphate battery system, because its SOC is in the platform area of ​​25% to 95%, it is impossible to use the open circuit voltage method to obtain its accurate SOC. Otherwise, there is little or even no chance of OCV (Open circuit voltage) correction based only on the two crossings of the platform area of ​​the lithium iron phosphate battery cell. Therefore, the output SOH of the lithium iron phosphate battery system mostly refers to the weighted combination of offline throughput and calendar life, without dynamic correction and with large deviation. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one purpose of the present invention is to propose a method for determining the SOH value of a battery system, which establishes a window mapping relationship between a reference cell and a target cell, uses the SOC of the reference cell to participate in calculating the SOH value of the target cell, improves the SOC estimation accuracy of the target cell in the platform area, and reduces the accumulated error during long-term use.

[0005] A second object of the present invention is to provide a computer-readable storage medium.

[0006] A third objective of the present invention is to provide a battery system.

[0007] A fourth object of the present invention is to provide a device for determining the SOH value of a battery system.

[0008] To achieve the above-mentioned purpose, an embodiment of the first aspect of the present invention proposes a method for determining the SOH value of a battery system, wherein the battery system includes a target battery cell and a reference battery cell, the initial capacity value of the reference battery cell is greater than the initial capacity value of the target battery cell, and the SOC acquisition accuracy of the reference battery cell is higher than the SOC acquisition accuracy of the target battery cell. The method includes: obtaining a first initial window upper limit value of the reference battery cell according to the initial capacity value of the target battery cell and the initial capacity value of the reference battery cell, and obtaining a second initial window upper limit value of the reference battery cell according to the charging cut-off voltage of the target battery cell, wherein the first initial window upper limit value is greater than the second initial window upper limit value; when it is determined that the SOC change value of the reference battery cell within a preset time is greater than or equal to a first preset value, obtaining the charge and discharge current and SOC change value of the reference battery cell within the preset time, and determining the SOH value of the target battery cell according to the initial capacity value of the reference battery cell, the charge and discharge current, the SOC change value, the preset time, the first initial window upper limit value, and the second initial window upper limit value.

[0009] In the SOH value determination method of the battery system of the embodiment of the present invention, the battery system includes a target battery cell and a reference battery cell, the initial capacity value of the reference battery cell is greater than the initial capacity value of the target battery cell, and the SOC acquisition accuracy of the reference battery cell is higher than the SOC acquisition accuracy of the target battery cell. The SOH value determination method of the battery system includes: firstly, obtaining a first initial window upper limit value of the reference battery cell according to the initial capacity value of the target battery cell and the initial capacity value of the reference battery cell, and obtaining a second initial window upper limit value of the reference battery cell according to the charging cut-off voltage of the target battery cell, wherein the first initial window upper limit value is greater than the second initial window upper limit value; then, when it is determined that the SOC change value of the reference battery cell within the preset time is greater than or equal to the first preset value, obtaining the charge and discharge current and SOC change value of the reference battery cell within the preset time, and determining the SOH value of the target battery cell according to the initial capacity value, charge and discharge current, SOC change value, preset time, first initial window upper limit value and second initial window upper limit value of the reference battery cell. Therefore, this method establishes a window mapping relationship between the reference cell and the target cell, and uses the SOC of the reference cell to participate in the calculation of the SOH value of the target cell, thereby improving the SOC estimation accuracy of the target cell in the platform area and reducing the accumulated error during long-term use.

[0010] In some embodiments of the present invention, the SOH value of the target battery cell is determined according to the formula Among them, SOH 目标 represents the SOH value of the target battery cell, A% represents the upper limit of the first initial window, B% represents the upper limit of the second initial window, I represents the charge and discharge current, t0 and t1 represent the start time and end time of the preset time, respectively, ΔSOC 参比 Indicates the SOC change value of the reference cell, C参比 Represents the initial capacity value of the reference cell.

[0011] In some embodiments of the present invention, the method also includes: obtaining multiple SOC values ​​of the target battery cell within the preset time; when the multiple SOC values ​​of the target battery cell are all greater than a first preset SOC value or are all less than a second preset SOC value, using a first correction method to correct the SOH value of the target battery cell; when the SOC values ​​of the target battery cell are all greater than or equal to the second preset SOC value and less than or equal to the first preset SOC value, using a second correction method to correct the SOH value of the target battery cell.

[0012] In some embodiments of the present invention, the SOH value of the target battery cell is corrected by a first correction method, including: obtaining the capacity difference and SOC difference of the target battery cell within the preset time; calculating the SOH correction value of the target battery cell according to the capacity difference and SOC difference of the target battery cell; and correcting the SOH value of the target battery cell according to the SOH correction value of the target battery cell.

[0013] In some embodiments of the present invention, a second correction method is used to correct the SOH value of the target battery cell, including: determining a first coefficient based on the first initial window upper limit value, and determining a second coefficient based on the second initial window upper limit value; obtaining the current initial window upper limit value of the reference battery cell; constructing correction parameters based on the first coefficient, the second coefficient, the first initial window upper limit value, the second initial window upper limit value and the current initial window upper limit value to correct the SOH value of the target battery cell, the current initial window upper limit value being greater than the second initial window upper limit value and less than the first initial window upper limit value.

[0014] In some embodiments of the present invention, a first coefficient is determined according to a first initial window upper limit value, including: determining a first capacity upper limit value of the reference battery cell according to the first initial window upper limit value; controlling the capacity of the reference battery cell to be less than the first capacity upper limit value, and obtaining a first group of SOH values ​​of the reference battery cell according to the capacity change of the reference battery cell; obtaining a first group of SOH values ​​of the target battery cell corresponding to the first group of SOH values ​​of the reference battery cell; and determining the first coefficient according to the first group of SOH values ​​of the reference battery cell and the first group of SOH values ​​of the target battery cell.

[0015] In some embodiments of the present invention, the second coefficient is determined according to the second initial window upper limit value, including: determining the second capacity upper limit value of the reference battery cell according to the second initial window upper limit value; controlling the capacity of the reference battery cell to be less than the second capacity upper limit value, and obtaining a second group of SOH values ​​of the reference battery cell according to the capacity change of the reference battery cell; obtaining a second group of SOH values ​​of the target battery cell corresponding to the second group of SOH values ​​of the reference battery cell; and determining the second coefficient according to the second group of SOH values ​​of the reference battery cell and the second group of SOH values ​​of the target battery cell.

[0016] In some embodiments of the present invention, the correction parameter is constructed by the following formula: Among them, K represents the correction parameter, K1 represents the first coefficient, K2 represents the second coefficient, A% represents the first initial window upper limit value, B% represents the second initial window upper limit value, and C% represents the current initial window upper limit value.

[0017] In some embodiments of the present invention, when the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is greater than or equal to a preset difference, the SOH output value of the target battery cell is determined based on the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction; when the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is less than the preset difference, the SOH value of the target battery cell after correction is used as the SOH output value of the target battery cell.

[0018] In some embodiments of the present invention, when the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is greater than or equal to a preset difference, the SOH output value of the target battery cell is calculated by the following formula: Among them, SOH 目标′ Indicates the SOH output value of the target cell, SOH 参比 represents the SOH value of the reference battery cell, A% represents the upper limit value of the first initial window, and B% represents the upper limit value of the second initial window.

[0019] To achieve the above objectives, a second aspect of the present invention proposes a computer-readable storage medium on which a battery system SOH value determination program is stored. When the battery system SOH value determination program is executed by a processor, the battery system SOH value determination method described in the above embodiment is implemented.

[0020] The computer-readable storage medium of this embodiment executes the SOH value determination program of the battery system stored thereon through the processor, which can establish a window mapping relationship between the reference battery cell and the target battery cell, calculate the SOH value of the target battery cell according to the SOC of the reference battery cell, improve the SOC estimation accuracy of the target battery cell in the platform area, and reduce the accumulated error during long-term use.

[0021] To achieve the above-mentioned purpose, an embodiment of the third aspect of the present invention proposes a battery system, which includes a memory, a processor, and a SOH value determination program of the battery system stored in the memory and executable on the processor. When the processor executes the SOH value determination program of the battery system, the SOH value determination method of the battery system in the above-mentioned embodiment is implemented.

[0022] The vehicle of this embodiment includes a memory, a processor, and a SOH value determination program of the battery system stored in the memory and executable on the processor. When the processor executes the SOH value determination program of the battery system, it is able to establish a window mapping relationship between a reference cell and a target cell, and obtain the SOH value of the target cell based on the SOC calculation of the reference cell, thereby improving the SOC estimation accuracy of the target cell in the platform area and reducing the accumulated error during long-term use.

[0023] To achieve the above-mentioned purpose, the fourth aspect of the present invention proposes a SOH value determination device for a battery system, wherein the battery system includes a target battery cell and a reference battery cell, the initial capacity value of the reference battery cell is greater than the initial capacity value of the target battery cell, and the SOC acquisition accuracy of the reference battery cell is higher than the SOC acquisition accuracy of the target battery cell. The device includes: an acquisition module, which is used to obtain a first initial window upper limit value of the reference battery cell according to the initial capacity value of the target battery cell and the initial capacity value of the reference battery cell, and to obtain a second initial window upper limit value of the reference battery cell according to the charging cut-off voltage of the target battery cell, wherein the first initial window upper limit value is greater than the second initial window upper limit value; a determination module, which is used to obtain the charge and discharge current, SOC change value and preset time of the reference battery cell when it is determined that the SOC change value of the reference battery cell within the preset time is greater than or equal to the first preset value, and determine the SOH value of the target battery cell according to the initial capacity value of the reference battery cell, the charge and discharge current, the SOC change value, the preset time, the first initial window upper limit value and the second initial window upper limit value.

[0024] The SOH value determination device of the battery system of the embodiment of the present invention includes an acquisition module and a determination module. First, the acquisition module acquires the first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell, and acquires the second initial window upper limit value of the reference cell according to the charging cut-off voltage of the target cell, and the first initial window upper limit value is greater than the second initial window upper limit value; then, when the SOC change value of the reference cell within the preset time is determined by the determination module to be greater than or equal to the first preset value, the charge and discharge current, SOC change value and preset time of the reference cell are acquired, and the SOH value of the target cell is determined according to the initial capacity value, charge and discharge current, SOC change value, preset time, first initial window upper limit value and second initial window upper limit value of the reference cell. Therefore, the SOH value determination device of the battery system of the embodiment of the present invention obtains the SOH value of the target cell according to the SOC calculation of the reference cell by establishing a window mapping relationship between the reference cell and the target cell, thereby improving the SOC estimation accuracy of the target cell in the platform area and reducing the accumulated error during long-term use.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of SOH estimation based on related technologies;

[0027] Figure 2 is a flow chart of a method for determining a battery system SOH value according to an embodiment of the present invention;

[0028] Figure 3 is a schematic diagram of initial windows of a reference cell and a target cell according to an embodiment of the present invention;

[0029] Figure 4 is a flow chart of a method for determining a battery system SOH value according to another embodiment of the present invention;

[0030] Figure 5 is a schematic diagram of the relationship between the process windows of a reference cell and a target cell according to another embodiment of the present invention;

[0031] Figure 6 Schematic diagram of the relationship between the aging rates of a lithium iron phosphate battery cell and a reference battery cell according to an embodiment of the present invention;

[0032] Figure 7 is a schematic diagram of the window relationship between a reference battery cell and a lithium iron phosphate battery cell after aging according to another embodiment of the present invention;

[0033] Figure 8 is a flow chart of a method for determining a battery system SOH value according to another embodiment of the present invention;

[0034] Fig. 9 is a flow chart of a method for determining a battery system SOH value according to another embodiment of the present invention;

[0035] Fig.10 is a flow chart of a method for determining a battery system SOH value according to another embodiment of the present invention;

[0036] Fig.11 is a flow chart of a method for determining a battery system SOH value according to another embodiment of the present invention;

[0037] Fig.12 is a flow chart of a method for determining a battery system SOH value according to another embodiment of the present invention;

[0038] Fig.13 is a strategy flow chart of a method for determining a battery system SOH value according to a specific embodiment of the present invention;

[0039] Fig.14 is a structural block diagram of a battery system according to an embodiment of the present invention;

[0040] Fig.15 4 is a structural block diagram of a device for determining a SOH value of a battery system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] The battery system and its SOH value determination method, device and storage medium according to embodiments of the present invention are described below with reference to the accompanying drawings.

[0043] At present, the SOH estimation method of the battery system in the related technology mainly uses the SOH algorithm based on the throughput table lookup as the basic algorithm, uses the ratio between the capacity difference and the SOC difference to correct the SOH, and designs the corresponding weight for the correction, and obtains the target SOH by weighted calculation. The output SOH tracks the target SOH, and the change per driving cycle does not exceed 0.1%. If it exceeds, it is directly calculated as 0.1% to reduce the error. Its process is as follows Figure 1 As shown, the offline SOH is calculated based on the throughput and calendar life, and the online SOH can be calculated using the capacity method, that is, the SOH is calculated based on the capacity difference and SOC difference between two wake-up cycles. The specific calculation formula is: ), where ΔQ is the capacity difference between the two wake-ups, and ΔSOC is the SOC difference between the two wake-ups.

[0044] In order to calculate the SOH value of the battery cell by the above method, it is necessary to ensure that the SOC of the battery cell can be accurately obtained. However, the SOC determination accuracy of batteries of different material types is not the same. For example, the SOC of the lithium iron phosphate battery cell has a platform area between 25% and 95%, that is, when the SOC of the lithium iron phosphate battery cell is between 25% and 95%, the correspondence between SOC and open circuit voltage is not accurate, so the open circuit voltage method cannot be used to obtain its accurate SOC, and further, it is impossible to make online corrections between platforms. The lithium iron phosphate battery cell needs to make two OCV (Open Circuit Voltage) corrections across the platform area. Therefore, for the lithium iron phosphate battery system, its output SOH mostly depends on the offline throughput and calendar life weighting, without online dynamic correction, so the deviation is large, which greatly reduces the SOH estimation accuracy.

[0045] The present invention provides a method for determining the SOH value of a battery system. The method is based on adding a reference cell with a high SOC estimation accuracy to the lithium iron phosphate battery system, and establishing a mapping relationship between the SOH of the reference cell and the lithium iron phosphate cell. The SOH of the lithium iron phosphate cell is obtained by calculating the SOH of the reference cell, aiming to improve the SOH estimation accuracy of the lithium iron phosphate battery pack. Of course, the SOH value determination method in this embodiment is not only applicable to lithium iron phosphate battery systems. As long as there is a battery system that cannot accurately obtain the battery SOC, the correct SOH value can be accurately calculated by the SOH value determination method of this embodiment.

[0046] Figure 2 is a flow chart of a method for determining a SOH value of a battery system according to an embodiment of the present invention.

[0047] The present invention proposes a method for determining the SOH value of a battery system, wherein the battery system includes a target battery cell and a reference battery cell, the initial capacity value of the reference battery cell is greater than the initial capacity value of the target battery cell, and the SOC acquisition accuracy of the reference battery cell is higher than the SOC acquisition accuracy of the target battery cell, such as Figure 2 As shown, the method comprises the following steps:

[0048] S10, obtaining a first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell, and obtaining a second initial window upper limit value of the reference cell according to the charging cut-off voltage of the target cell, wherein the first initial window upper limit value is greater than the second initial window upper limit value.

[0049] Specifically, the battery system includes a target cell and a reference cell, wherein the reference cell and the target cell can be connected in series and arranged in the battery system, and the initial capacity value of the reference cell is greater than the initial capacity value of the target cell, so that during the use of the reference cell and the target cell, the power of the target cell is used up before the power in the reference cell is used up, so that the power of the target cell can be calculated by the reference cell until the power in the target cell is used up. Moreover, in this embodiment, the condition that the initial capacity value of the reference cell is greater than the initial capacity value of the target cell needs to be satisfied in order to obtain the first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell.

[0050] In addition, this embodiment further limits the SOC acquisition accuracy of the reference battery cell to be higher than the SOC acquisition accuracy of the target battery cell. The reason for setting the reference battery cell in this embodiment is that the SOC of the target battery cell cannot be accurately acquired in the platform area. Therefore, by limiting the SOC acquisition accuracy of the reference battery cell to be higher than the SOC acquisition accuracy of the target battery cell, the reference battery cell can accurately acquire its SOC value.

[0051] After determining the reference cell of the target cell, the present embodiment can further calculate the first initial window upper limit value and the second initial window upper limit value of the reference cell. In some embodiments of the present invention, the first initial window upper limit value of the reference cell is obtained according to the following formula: Among them, A% represents the upper limit of the first initial window, C 参比 Indicates the initial capacity value of the reference cell, C 目标 Indicates the initial capacity value of the target battery cell.

[0052] Specifically, the reference cell window ratio is initially adjusted to make its available capacity consistent with the target cell full window capacity, such as Figure 3 As shown, assuming the initial total capacity of the reference cell is C 参比 , the first initial window lower limit is 0%, the first initial window upper limit is A%, and the target cell full window capacity is C 目标 , then C is satisfied 参比 *A%=C 目标 .

[0053] In some embodiments of the present invention, the second initial window upper limit value of the reference cell is obtained according to the charging cut-off voltage of the target cell, such as Figure 4 As shown, the following steps are included:

[0054] S301, obtaining a voltage upper limit value of a reference battery cell according to a charging cut-off voltage of a target battery cell.

[0055] S302, obtaining a second initial window upper limit value of a reference cell by looking up a table according to the voltage upper limit value.

[0056] Specifically, the target cell is charged first. When the target cell is fully charged, its charging voltage reaches the charging cut-off voltage. Then, it is determined whether the target cell is fully charged by detecting whether the charging voltage of the target cell has reached the charging cut-off voltage. When it is determined that the target cell has been fully charged, the voltage of the reference cell at this time is obtained as the voltage upper limit value, and then the second initial window upper limit value of the reference cell is obtained by looking up the table.

[0057] Specific as Figure 5 As shown, assuming that the charging cut-off voltage of the target battery cell is 3.65 volts, when the charging voltage of the reference battery cell is also 3.65 volts, the SOC of the reference battery cell at this time is determined, and the SOC value is used as the second initial window upper limit value B% of the reference battery cell.

[0058] It should be noted that the first initial window upper limit value and the second initial window upper limit value in this embodiment are different, mainly because the battery cell will age during use, so that the capacity of the battery cell also changes, and the aging rate of the reference battery cell and the target battery cell is also different. It should be noted that the aging rate of the reference battery cell in this embodiment is lower than the aging rate of the target battery cell, so that the performance of the reference battery cell is better than that of the target battery cell.

[0059] More specifically, assuming that the target battery cell in this embodiment is a lithium iron phosphate battery cell, and assuming that the cycle life of the reference battery cell is better than that of the lithium iron phosphate battery cell, the aging relationship thereof should satisfy the following: Figure 6 As shown, the aging rate of the reference cell is assumed to be V 参比 , the aging rate of lithium iron phosphate battery is V LFP , then V 参比 ≤V LFP Because the aging rate within the reference cell window is lower than that of the Fe-Li cell, during the aging process, the system capacity follows the Fe-Li battery capacity, and the reference cell adjusts the upper limit window based on the Fe-Li cell. The window relationship is as follows: Figure 7 As shown, the upper limit B% of the window of the reference cell here, the bottom window of the reference cell and the lithium iron phosphate cell are consistent, which can be mapped by fully charging the lithium iron phosphate, that is, the SOC reaches 100%.

[0060] The following lists the relationship between the capacities of the target cell and the reference cell through the first initial window upper limit value A% and the second initial window upper limit value B%. After both the target cell and the reference cell have aged and decayed, since the capacities of the two are the same, the following formula C is obtained. 参比 *B%*SOH 参比 =C 目标 *SOH 目标 , where C 参比 Indicates the initial capacity value of the reference cell, C 目标 Indicates the initial capacity value of the target battery cell, SOH 参比Indicates the SOH value of the reference battery, SOH 目标 represents the SOH value of the target battery cell. That is, in the above formula, the left side of the equal sign represents the capacity of the target battery cell after aging and decay when fully charged in the reference battery cell after aging and decay, and the right side of the equal sign represents the capacity of the target battery cell after aging and decay when fully charged. According to the calculation formula for the first initial window upper limit value A% in the above embodiment, C 参比 *A%=C 目标 , so that we can get Among them, SOH 目标 is the SOH value of the target battery cell, SOH 参比 is the SOH value of the reference cell.

[0061] S20, when it is determined that the SOC change value of the reference battery cell within the preset time is greater than or equal to the first preset value, obtain the charge and discharge current and SOC change value of the reference battery cell within the preset time, and determine the SOH value of the target battery cell according to the initial capacity value, charge and discharge current, SOC change value, preset time, first initial window upper limit value and second initial window upper limit value of the reference battery cell.

[0062] Specifically, it can be seen from the description of the above embodiment that the SOH value of the target battery cell, i.e. Among them, the specific method of obtaining the first initial window upper limit value A% and the second initial window upper limit value B% can refer to the description of the above embodiment. It can be seen that there is a mapping relationship between the SOH value of the target battery cell and the SOH value of the reference battery cell, so the SOH value of the target battery cell can be obtained by calculating the SOH value of the reference battery cell and then looking up the table.

[0063] More specifically, in order to improve the calculation accuracy, the present embodiment may determine a first preset value, and the SOH reference value is calculated only when the SOC change value of the reference battery within the preset time is greater than or equal to the first preset value, wherein the value range of the first preset value may be 30%-70%. For example, the SOH value of the reference battery is calculated only when the SOC change value of the reference battery within the preset time is greater than or equal to 50%. In the present embodiment, the SOH value of the reference battery is calculated by the capacity change, and the SOH value can be determined specifically according to the ratio between the actual charge and discharge amount of the reference battery within the preset time and the rated discharge amount. 参比 Then, through the formula The SOH value of the target battery cell is calculated.

[0064] In this embodiment, the SOH value of the target battery cell is determined according to the following formula: Among them, SOH 目标represents the SOH value of the target battery cell, A% represents the upper limit of the first initial window, B% represents the upper limit of the second initial window, I represents the charge and discharge current, t0 and t1 represent the start and end time of the preset time respectively, ΔSOC 参比 Indicates the SOC change value of the reference cell, C 参比 Indicates the initial capacity value of the reference battery.

[0065] Specifically, in the above formula middle, is the SOH value of the reference cell, where ΔSOC 参比 *C 参比 *A% represents the rated charge or discharge capacity of the reference cell between t0 and t1. Indicates the actual charge or discharge of the reference cell between time t0 and time t1, then the actual charge of the reference cell is divided by the rated charge to obtain the SOH value of the reference cell, or the actual discharge of the reference cell is divided by the rated discharge to obtain the SOH value of the reference cell. It can be understood that the SOC value of the reference cell can be obtained based on the open circuit voltage, because the reference cell does not have a platform area, and a higher precision SOC value can be obtained.

[0066] For example, the preset time in this embodiment is 10 seconds, time t0 is the 0th second, and time t1 is the 10th second. The discharge current of the reference battery cell within the 10 seconds is obtained to determine the actual discharge amount of the reference battery cell within the preset time, and then the SOC change value of the reference battery cell within the preset time is obtained through the open circuit voltage, and then the rated discharge amount of the reference battery cell within the preset time is determined according to the initial power of the reference battery cell, and then the SOH value of the reference battery cell can be determined according to the actual discharge amount and the rated discharge amount of the reference battery cell.

[0067] In some embodiments of the present invention, Figure 8 As shown, the method for determining the SOH value of the battery system also includes the following steps:

[0068] S401, obtaining multiple SOC values ​​of a target battery cell within a preset time.

[0069] S402, when multiple SOC values ​​of the target battery cell are greater than the first preset SOC value or less than the second preset SOC value, the SOH value of the target battery cell is corrected by the first correction method; when the SOC values ​​of the target battery cell are greater than or equal to the second preset SOC value and less than or equal to the first preset SOC value, the SOH value of the target battery cell is corrected by the second correction method.

[0070] Specifically, the SOH value of the target battery cell can be calculated through the above embodiment, and this embodiment corrects the SOH value of the target battery cell obtained in the above embodiment. The specific correction method is to calculate the SOH value of the target battery cell by other methods, and compare it with the SOH value of the target battery cell before correction to determine the corrected SOH value of the target battery cell.

[0071] More specifically, since the SOC of the lithium iron phosphate battery cell is in the 25% to 95% platform area, the open circuit voltage method cannot be used to obtain its accurate SOC, so different correction methods can be determined according to the SOC value of the target battery cell within the preset time. For example, when multiple SOC values ​​of the target battery cell within the preset time are greater than 95% or less than 25%, the first correction method is used to correct the SOH value of the target battery cell. When the SOC values ​​of the target battery cell are greater than or equal to 25% and less than or equal to 95%, the second correction method is used to correct the SOH value of the target battery cell. It should be noted that the first preset SOC value and the second preset SOC value in this embodiment can be determined according to the SOC platform area of ​​the target battery cell.

[0072] In some embodiments of the present invention, the SOH value of the target battery cell is corrected by a first correction method, such as Fig. 9 As shown, the following steps are included:

[0073] S501, obtaining a capacity difference and an SOC difference of a target battery cell within a preset time.

[0074] S502: Calculate a SOH correction value of the target battery cell according to the capacity difference and the SOC difference of the target battery cell.

[0075] S503: Correct the SOH value of the target battery cell according to the SOH correction value of the target battery cell.

[0076] Specifically, when multiple SOC values ​​of the target battery cell are greater than the first preset SOC value or less than the second preset SOC value, it means that the SOC change value of the current target battery cell is not in the platform area, and is not affected by the difficulty in determining the SOC value in the platform area. It can be directly corrected according to the capacity difference △Q and SOC difference △SOC of the target battery cell within the preset time, according to the value calculated by △Q / △SOC. For example, the current iron-lithium battery cell can be Then the current SOH of the iron-lithium battery cell is averaged with the value before correction to obtain an average value, and the average value is used as the corrected SOH value of the iron-lithium battery cell. It should be noted that the method of determining the corrected SOH of the iron-lithium battery cell by averaging described above is only one of the multiple correction methods in this embodiment, and correction can also be performed by assigning weights, etc., which is not specifically limited here.

[0077] In some embodiments of the present invention, the SOH value of the target battery cell is corrected by a second correction method, such as Fig.10 As shown, the following steps are included:

[0078] S601, determining a first coefficient according to a first initial window upper limit value, and determining a second coefficient according to a second initial window upper limit value.

[0079] First of all, it should be explained that the second correction method is to recalculate the SOH value of the target battery cell by linear derivation. During the linear derivation process, the first coefficient corresponding to the first initial window upper limit value A% and the second coefficient corresponding to the second initial window upper limit value B% are respectively the two endpoints in the linear derivation process.

[0080] In some embodiments of the present invention, the first coefficient is determined according to the first initial window upper limit value, such as Fig.11 As shown, the following steps are included:

[0081] S701, determining a first capacity upper limit value of a reference cell according to a first initial window upper limit value.

[0082] S702, controlling the capacity of the reference battery cell to be less than a first capacity upper limit value, and obtaining a first group of SOH values ​​of the reference battery cell according to a change in the capacity of the reference battery cell.

[0083] S703 , obtaining a first group of SOH values ​​of target cells corresponding to a first group of SOH values ​​of reference cells.

[0084] S704 , determining a first coefficient according to a first group of SOH values ​​of reference cells and a first group of SOH values ​​of target cells.

[0085] Specifically, the capacity of the reference cell is first controlled to be below the first capacity upper limit value corresponding to the first initial window upper limit value, and then the SOH values ​​of multiple reference cells and the corresponding SOH values ​​of multiple target cells are tested experimentally, and the SOH mapping relationship between the reference cell and the target cell is established based on the multiple SOH values ​​obtained. When the first initial window upper limit value of the reference cell is A%, the SOH value of the reference cell and the SOH value of the target cell can be obtained through the multiple groups of SOH tested experimentally to meet the SOH 参比(循环上限A％) =SOH 目标(循环) *K1(1≤K1≤1.1), where K1 is the first coefficient, and 1≤K1≤1.1. It can be understood that when obtaining the SOH value of the reference battery cell and the SOH value of the corresponding target battery cell, a cyclic acquisition can be performed to improve the accuracy of the acquired data.

[0086] In some embodiments of the present invention, the second coefficient is determined according to the second initial window upper limit value, such as Fig.12 As shown, the following steps are included:

[0087] S801, determining a second capacity upper limit value of a reference cell according to a second initial window upper limit value.

[0088] S802, controlling the capacity of the reference battery cell to be less than a second capacity upper limit value, and obtaining a second set of SOH values ​​of the reference battery cell according to the capacity change of the reference battery cell.

[0089] S803, obtaining a second group of SOH values ​​of the target battery cells corresponding to the second group of SOH values ​​of the reference battery cells;

[0090] S804 , determining a second coefficient according to a second group of SOH values ​​of the reference battery cells and a second group of SOH values ​​of the target battery cells.

[0091] Specifically, the capacity of the reference cell is first controlled to be below the second capacity upper limit value corresponding to the second initial window upper limit value, and then the SOH values ​​of multiple reference cells and the corresponding SOH values ​​of multiple target cells are tested experimentally, and the SOH mapping relationship between the reference cell and the target cell is established based on the multiple SOH values ​​obtained. When the second initial window upper limit value of the reference cell is B%, the SOH value of the reference cell and the SOH value of the target cell can be obtained through the multiple groups of SOH tested experimentally to meet the SOH 参比(循环上限B％) =SOH 目标(循环) *K2 (K2>K1), where K2 is the first coefficient. In some embodiments, the relationship between the second initial window upper limit value B% and the first initial window upper limit value A% is B%=0.65*A%. It should be noted that the multiple relationship between the second initial window upper limit value B% and the first initial window upper limit value A% in this embodiment can be determined by the service life of the target battery cell. For example, when the capacity retention rate of the lithium iron phosphate battery cell is 65% at the end of the life of the lithium iron phosphate battery cell, the multiple relationship between the second initial window upper limit value B% and the first initial window upper limit value A% is 0.65 times.

[0092] It is understandable that when obtaining the SOH value of the reference battery cell and the SOH value of the corresponding target battery cell, the acquisition may be performed cyclically to improve the accuracy of the acquired data.

[0093] S602, obtaining the current initial window upper limit value of the reference cell.

[0094] S603, constructing correction parameters to correct the SOH value of the target battery cell according to the first coefficient, the second coefficient, the first initial window upper limit value, the second initial window upper limit value and the current initial window upper limit value, wherein the current initial window upper limit value is greater than the second initial window upper limit value and less than the first initial window upper limit value.

[0095] Specifically, in this embodiment, after the coefficients of the two endpoints of the mapping relationship between the SOH value of the target battery cell and the SOH value of the reference battery cell are determined as the first coefficient and the second coefficient, the coefficient between the target battery cell SOH value corresponding to the current initial window upper limit value of the reference battery cell and the reference battery cell SOH value can be determined according to the linear relationship. First, the current initial window upper limit value of the reference battery cell is obtained as C%, then the relationship between the SOH value of the reference battery cell and the SOH value of the target battery cell is:

[0096] In the above formula, Defined as Then we can get In this embodiment, the correction parameter is So that SOH 目标 =SOH 参比 *K. In this embodiment, after determining the correction parameter and calculating the corrected SOH value of the target battery cell according to the correction parameter, the SOH value of the output target battery cell can be determined according to the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction. For example, the SOH values ​​of the target battery cell before correction and after correction can be averaged to obtain the SOH value of the output target battery cell.

[0097] In addition, it should be noted that the first initial window upper limit value in the present embodiment is the first SOC value corresponding to the power of the reference cell and the target cell when both the reference cell and the target cell are not aged and decayed, and the second initial window upper limit value is the second SOC value corresponding to the power of the reference cell and the target cell when the life of the target cell ends. Therefore, when the target cell is in use, its power is generally between the first SOC value and the second SOC value. Therefore, the current initial window upper limit value in the present embodiment is between the second initial window upper limit value and the first initial window upper limit value, that is, the current initial window upper limit value is greater than the second initial window upper limit value and less than the first initial window upper limit value.

[0098] In some embodiments of the present invention, the method for determining the SOH value of the battery system further includes: when the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is greater than or equal to a preset difference, determining the SOH output value of the target battery cell according to the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction. When the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is less than the preset difference, using the SOH value of the target battery cell after correction as the SOH output value of the target battery cell.

[0099] After the corrected SOH value of the target battery is obtained by adopting the second correction method, a more accurate SOH value of the target battery cell can be obtained based on the SOH of the target battery cell before and after correction.

[0100] Specifically, the difference between the SOH value of the target cell before correction and the SOH value after correction is first determined. When the difference is greater than or equal to the preset difference, it means that the SOH value of the target cell before correction and after correction differs greatly, and further calculation and determination of the SOH output value of the target cell are required. In some specific embodiments, the SOH output value of the target cell can be calculated by the following formula: Among them, SOH 目标′ Indicates the SOH output value of the target battery cell, K*SOH 参比 Indicates the corrected SOH value of the target cell. The SOH value of the target battery cell before correction and the SOH value after correction can be found in the specific description of the above embodiment, which will not be repeated here.

[0101] When the difference between the SOH value of the target battery cell before correction and the SOH value after correction is less than the preset difference, the SOH value of the target battery cell after correction can be directly used as the SOH output value of the target battery cell.

[0102] For example, the preset difference in this example is 5%. When the difference between the corrected SOH value of the target cell and the SOH value before correction is greater than or equal to 5%, the SOH values ​​of the target cell before and after correction are weighted averaged to calculate the SOH output value of the target cell; and if the difference between the corrected SOH value of the target cell and the SOH value before correction is less than 5%, the corrected SOH value of the target cell, i.e., K*SOH 参比 As the SOH output value of the target battery cell.

[0103] As a specific example of the present invention, Fig.13 The following is a strategy flow chart of a method for determining the SOH value of a battery system according to a specific embodiment of the present invention, wherein the detailed control strategy may include the following steps:

[0104] S901, start booting.

[0105] S902, determining a reference cell and a first initial window upper limit value A% and a second initial window upper limit value B% of the reference cell.

[0106] S903, calculating the current initial window upper limit value of the reference cell in real time.

[0107] S904, obtaining the SOH of the iron-lithium battery cell according to the reference battery cell SOH through a mapping relationship.

[0108] S905, judging whether the iron-lithium battery cell meets the platform area OCV correction, if yes, jumping to step S907. If no, jumping to step S906.

[0109] S906, judgment Is it established? If yes, jump to step S908. If no, jump to step S909.

[0110] S907, correct the current SOH of the lithium iron battery cell according to △Q / △SOC.

[0111] S908, according to Weighted average correction.

[0112] S909, output SOH LFP Finish.

[0113] It should be noted that the above step 901 may specifically call a SOH value determination program of the battery system, thereby triggering the start of the SOH value determination method of the battery system.

[0114] In summary, the SOH value determination method of the battery system in the embodiment of the present invention establishes a window mapping relationship between the reference battery cell and the target battery cell, calculates the SOH value of the target battery cell according to the SOC of the reference battery cell, thereby improving the SOC estimation accuracy of the target battery cell in the platform area and reducing the accumulated error during long-term use.

[0115] Furthermore, the present invention also proposes a computer-readable storage medium on which a SOH value determination program for a battery system is stored. When the SOH value determination program for a battery system is executed by a processor, the SOH value determination method for a battery system in the above-mentioned embodiment is implemented.

[0116] According to the computer-readable storage medium of an embodiment of the present invention, by executing the SOH value determination program of the battery system stored thereon by the processor, a window mapping relationship can be established between the reference battery cell and the target battery cell, and the SOH value of the target battery cell can be obtained according to the SOC calculation of the reference battery cell, thereby improving the SOC estimation accuracy of the target battery cell in the platform area and reducing the accumulated error during long-term use.

[0117] Fig.14 is a structural block diagram of a battery system according to an embodiment of the present invention.

[0118] Furthermore, if Fig.14As shown, the present invention also proposes a battery system 100, which includes a memory 101, a processor 102, and a SOH value determination program for the battery system stored in the memory 101 and executable on the processor 102. When the processor 102 executes the program, the SOH value determination method for the battery system in the above-mentioned embodiment is implemented.

[0119] The battery system of the embodiment of the present invention executes the SOH value determination program of the battery system stored in the memory through the processor, and can establish a window mapping relationship between the reference battery cell and the target battery cell, calculate the SOH value of the target battery cell according to the SOC of the reference battery cell, improve the SOC estimation accuracy of the target battery cell in the platform area, and reduce the accumulated error during long-term use.

[0120] Fig.15 4 is a structural block diagram of a device for determining a SOH value of a battery system according to an embodiment of the present invention.

[0121] Furthermore, if Fig.15 As shown, the present invention proposes a SOH value determination device 200 for a battery system, the battery system includes a target battery cell and a reference battery cell, the initial capacity value of the reference battery cell is greater than the initial capacity value of the target battery cell, the SOC acquisition accuracy of the reference battery cell is higher than the SOC acquisition accuracy of the target battery cell, and the SOH value determination device 200 for the battery system includes an acquisition module 201 and a determination module 202.

[0122] Among them, in this embodiment, the acquisition module 201 is used to obtain the first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell, and to obtain the second initial window upper limit value of the reference cell according to the charging cut-off voltage of the target cell, and the first initial window upper limit value is greater than the second initial window upper limit value; the determination module 202 is used to obtain the charge and discharge current, SOC change value and preset time of the reference cell when it is determined that the SOC change value of the reference cell within the preset time is greater than or equal to the first preset value, and determine the SOH value of the target cell according to the initial capacity value, charge and discharge current, SOC change value, preset time, the first initial window upper limit value and the second initial window upper limit value of the reference cell.

[0123] In one embodiment of the present invention, the acquisition module 201 is specifically used to obtain the first initial window upper limit value of the reference battery cell according to the following formula: Among them, A% represents the upper limit of the first initial window, C 参比 Indicates the initial capacity value of the reference cell, C 目标 Indicates the initial capacity value of the target battery cell.

[0124] In one embodiment of the present invention, the acquisition module 201 is specifically used to acquire the voltage upper limit value of the reference cell according to the charging cut-off voltage of the target cell; and acquire the second initial window upper limit value of the reference cell by looking up the voltage upper limit value in a table.

[0125] In one embodiment of the present invention, the determination module 202 is specifically configured to determine the SOH value of the target battery cell according to the following formula: Among them, SOH 目标 represents the SOH value of the target battery cell, A% represents the upper limit of the first initial window, B% represents the upper limit of the second initial window, I represents the charge and discharge current, t0 and t1 represent the start and end time of the preset time respectively, ΔSOC 参比 Indicates the SOC change value of the reference cell, C 参比 Indicates the initial capacity value of the reference battery.

[0126] In one embodiment of the present invention, the target battery cell includes a lithium iron battery cell.

[0127] In one embodiment of the present invention, the SOH value determination device of the battery system also includes a correction module for obtaining multiple SOC values ​​of the target battery cell within a preset time; when the multiple SOC values ​​of the target battery cell are all greater than a first preset SOC value or less than a second preset SOC value, the SOH value of the target battery cell is corrected using a first correction method; when the SOC values ​​of the target battery cell are all greater than or equal to the second preset SOC value and less than or equal to the first preset SOC value, the SOH value of the target battery cell is corrected using a second correction method.

[0128] In one embodiment of the present invention, the correction module is specifically used to obtain the capacity difference and SOC difference of the target battery cell within a preset time; calculate the SOH correction value of the target battery cell according to the capacity difference and SOC difference of the target battery cell; and correct the SOH value of the target battery cell according to the SOH correction value of the target battery cell.

[0129] In one embodiment of the present invention, the correction module is specifically used to determine a first coefficient according to a first initial window upper limit value, and to determine a second coefficient according to a second initial window upper limit value; to obtain a current initial window upper limit value of a reference cell; and to construct correction parameters according to the first coefficient, the second coefficient, the first initial window upper limit value, the second initial window upper limit value and the current initial window upper limit value to correct the SOH value of the target cell, wherein the current initial window upper limit value is greater than the second initial window upper limit value and less than the first initial window upper limit value.

[0130] In one embodiment of the present invention, the correction module is specifically used to determine a first capacity upper limit value of a reference battery cell according to a first initial window upper limit value; control the capacity of the reference battery cell to be less than the first capacity upper limit value, and obtain a first group of SOH values ​​of the reference battery cell according to the capacity change of the reference battery cell; obtain a first group of SOH values ​​of the target battery cell corresponding to the first group of SOH values ​​of the reference battery cell; and determine a first coefficient according to the first group of SOH values ​​of the reference battery cell and the first group of SOH values ​​of the target battery cell.

[0131] In one embodiment of the present invention, the correction module is specifically used to determine a second capacity upper limit value of a reference battery cell according to a second initial window upper limit value; control the capacity of the reference battery cell to be less than the second capacity upper limit value, and obtain a second group of SOH values ​​of the reference battery cell according to the capacity change of the reference battery cell; obtain a second group of SOH values ​​of the target battery cell corresponding to the second group of SOH values ​​of the reference battery cell; and determine a second coefficient according to the second group of SOH values ​​of the reference battery cell and the second group of SOH values ​​of the target battery cell.

[0132] In one embodiment of the present invention, the correction module is specifically used to construct the correction parameter by the following formula: Wherein, K represents a correction parameter, K1 represents a first coefficient, K2 represents a second coefficient, A% represents a first initial window upper limit value, B% represents a second initial window upper limit value, and C% represents a current initial window upper limit value.

[0133] In one embodiment of the present invention, the correction module is specifically used to determine the SOH output value of the target battery cell according to the SOH value before correction and the SOH value after correction of the target battery cell when the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is greater than or equal to a preset difference; when the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is less than the preset difference, use the SOH value after correction of the target battery cell as the SOH output value of the target battery cell.

[0134] In one embodiment of the present invention, the correction module is specifically used to calculate the SOH output value of the target battery cell by the following formula when the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is greater than or equal to a preset difference: Among them, SOH 目标′ Indicates the SOH output value of the target battery cell, SOH 参比 represents the SOH value of the reference battery cell, A% represents the upper limit value of the first initial window, and B% represents the upper limit value of the second initial window.

[0135] In summary, the SOH value determination device of the battery system of the embodiment of the present invention includes an acquisition module and a determination module. First, the acquisition module acquires the first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell, and acquires the second initial window upper limit value of the reference cell according to the charging cut-off voltage of the target cell, and the first initial window upper limit value is greater than the second initial window upper limit value; then, when the SOC change value of the reference cell within the preset time is determined by the determination module to be greater than or equal to the first preset value, the charge and discharge current, SOC change value and preset time of the reference cell are acquired, and the SOH value of the target cell is determined according to the initial capacity value, charge and discharge current, SOC change value, preset time, first initial window upper limit value and second initial window upper limit value of the reference cell. Therefore, the SOH value determination device of the battery system of the embodiment of the present invention obtains the SOH value of the target cell according to the SOC calculation of the reference cell by establishing a window mapping relationship between the reference cell and the target cell, thereby improving the SOC estimation accuracy of the target cell in the platform area and reducing the accumulated error during long-term use.

[0136] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0137] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0138] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0139] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0140] In addition, the terms "first", "second", etc. used in the embodiments of the present invention are only used for descriptive purposes and should not be understood as indicating or implying relative importance, or implicitly indicating the number of technical features indicated in the present embodiment. Therefore, the features defined by the terms "first", "second", etc. in the embodiments of the present invention can explicitly or implicitly indicate that the embodiment includes at least one of the features. In the description of the present invention, the word "multiple" means at least two or two or more, such as two, three, four, etc., unless otherwise clearly and specifically defined in the embodiments.

[0141] In the present invention, unless otherwise clearly specified or limited in the embodiments, the terms "installed", "connected", "connected" and "fixed" etc. in the embodiments should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integrated connection. It can be understood that it can also be a mechanical connection, an electrical connection, etc.; of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements, or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific implementation situation.

[0142] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0143] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for determining the SOH value of a battery system, characterized in that: The battery system includes a target battery cell and a reference battery cell, the initial capacity value of the reference battery cell is greater than the initial capacity value of the target battery cell, the SOC acquisition accuracy of the reference battery cell is higher than the SOC acquisition accuracy of the target battery cell, and the method includes: Obtaining a first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell, and obtaining a second initial window upper limit value of the reference cell according to the charging cut-off voltage of the target cell, wherein the first initial window upper limit value is greater than the second initial window upper limit value; When it is determined that the SOC change value of the reference battery cell within the preset time is greater than or equal to the first preset value, the charge and discharge current and the SOC change value of the reference battery cell within the preset time are obtained, and the SOH value of the target battery cell is determined according to the initial capacity value of the reference battery cell, the charge and discharge current, the SOC change value, the preset time, the first initial window upper limit value, and the second initial window upper limit value; The SOH value of the target cell is determined according to the following formula: Among them, SOH 目标 represents the SOH value of the target battery cell, A% represents the upper limit of the first initial window, B% represents the upper limit of the second initial window, I represents the charge and discharge current, t0 and t1 represent the start time and end time of the preset time, respectively, ΔSOC 参比 Indicates the SOC change value of the reference cell, C 参比 Represents the initial capacity value of the reference cell.

2. The determination method according to claim 1, characterized in that: The method further comprises: Obtain multiple SOC values ​​of the target battery cell within the preset time; When multiple SOC values ​​of the target battery cell are all greater than a first preset SOC value or are all less than a second preset SOC value, the SOH value of the target battery cell is corrected using a first correction method; when the SOC values ​​of the target battery cell are all greater than or equal to the second preset SOC value and less than or equal to the first preset SOC value, the SOH value of the target battery cell is corrected using a second correction method.

3. The determination method according to claim 2, characterized in that: The SOH value of the target battery cell is corrected by adopting a first correction method, including: Obtaining a capacity difference and an SOC difference of the target battery cell within the preset time; Calculate the SOH correction value of the target battery cell according to the capacity difference and SOC difference of the target battery cell; The SOH value of the target battery cell is corrected according to the SOH correction value of the target battery cell.

4. The determination method according to claim 2, characterized in that: The SOH value of the target battery cell is corrected by a second correction method, including: Determine a first coefficient according to the first initial window upper limit value, and determine a second coefficient according to the second initial window upper limit value; Obtaining the current initial window upper limit value of the reference cell; The SOH value of the target battery cell is corrected by constructing correction parameters based on the first coefficient, the second coefficient, the first initial window upper limit value, the second initial window upper limit value and the current initial window upper limit value, and the current initial window upper limit value is greater than the second initial window upper limit value and less than the first initial window upper limit value.

5. The determination method according to claim 4, characterized in that: Determining a first coefficient according to the first initial window upper limit value includes: Determine a first capacity upper limit value of the reference cell according to the first initial window upper limit value; Controlling the capacity of the reference battery cell to be less than the first capacity upper limit value, and obtaining a first group of SOH values ​​of the reference battery cell according to the capacity change of the reference battery cell; Acquire a first group of SOH values ​​of the target battery cells corresponding to the first group of SOH values ​​of the reference battery cells; A first coefficient is determined according to a first group of SOH values ​​of the reference battery cells and a first group of SOH values ​​of the target battery cells.

6. The determination method according to claim 4, characterized in that: Determining a second coefficient according to the second initial window upper limit value includes: Determine a second capacity upper limit value of the reference cell according to the second initial window upper limit value; Controlling the capacity of the reference battery cell to be less than the second capacity upper limit value, and obtaining a second group of SOH values ​​of the reference battery cell according to the capacity change of the reference battery cell; Acquire a second group of SOH values ​​of the target battery cells corresponding to the second group of SOH values ​​of the reference battery cells; A second coefficient is determined according to the second group of SOH values ​​of the reference battery cells and the second group of SOH values ​​of the target battery cells.

7. The determination method according to claim 4, characterized in that: The correction parameter is constructed by the following formula, Among them, K represents the correction parameter, K1 represents the first coefficient, K2 represents the second coefficient, A% represents the first initial window upper limit value, B% represents the second initial window upper limit value, and C% represents the current initial window upper limit value.

8. The determination method according to claim 7, characterized in that: The method further comprises: When the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is greater than or equal to a preset difference, determining the SOH output value of the target battery cell according to the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction; When the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is less than the preset difference, the SOH value of the target battery cell after correction is used as the SOH output value of the target battery cell.

9. The determination method according to claim 8, characterized in that: When the difference between the SOH value of the target battery cell before correction and the SOH value of the target battery cell after correction is greater than or equal to a preset difference, the SOH output value of the target battery cell is calculated by the following formula: Among them, SOH 目标′ Indicates the SOH output value of the target cell, SOH 参比 represents the SOH value of the reference battery cell, A% represents the upper limit value of the first initial window, and B% represents the upper limit value of the second initial window.

10. A computer-readable storage medium, characterized in that: A battery system SOH value determination program is stored thereon, and when the battery system SOH value determination program is executed by a processor, a battery system SOH value determination method according to any one of claims 1 to 9 is implemented.

11. A battery system, characterized in that: The invention comprises a memory, a processor and a SOH value determination program of a battery system which is stored in the memory and can be run on the processor. When the processor executes the SOH value determination program of the battery system, the SOH value determination method of the battery system according to any one of claims 1 to 9 is implemented.

12. A device for determining the SOH value of a battery system, characterized in that: The battery system includes a target battery cell and a reference battery cell, the initial capacity value of the reference battery cell is greater than the initial capacity value of the target battery cell, the SOC acquisition accuracy of the reference battery cell is higher than the SOC acquisition accuracy of the target battery cell, and the device includes: An acquisition module, used to acquire a first initial window upper limit value of the reference cell according to the initial capacity value of the target cell and the initial capacity value of the reference cell, and to acquire a second initial window upper limit value of the reference cell according to the charging cut-off voltage of the target cell, wherein the first initial window upper limit value is greater than the second initial window upper limit value; A determination module, configured to obtain the charge and discharge current, SOC change value and preset time of the reference battery cell when it is determined that the SOC change value of the reference battery cell within the preset time is greater than or equal to a first preset value, and determine the SOH value of the target battery cell according to the initial capacity value of the reference battery cell, the charge and discharge current, the SOC change value, the preset time, the first initial window upper limit value and the second initial window upper limit value; The SOH value of the target cell is determined according to the following formula: Among them, SOH 目标 represents the SOH value of the target battery cell, A% represents the upper limit of the first initial window, B% represents the upper limit of the second initial window, I represents the charge and discharge current, t0 and t1 represent the start time and end time of the preset time, respectively, ΔSOC 参比 Indicates the SOC change value of the reference cell, C 参比 Represents the initial capacity value of the reference cell.

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