A capacity correction method of a battery pack

Abstract

The application provides a capacity correction method of a battery pack, comprising the following steps: performing static test and charging experiment on an electric core in advance to obtain a curve of the electric core aging, temperature, circuit and OCV and a relationship table of aging degree, battery temperature, open circuit voltage and electric quantity value at different time in a charging process; obtaining a best charging rate relationship table of the electric core at different temperatures and electric quantities; obtaining the electric quantity of each electric core of the battery pack, the real-time electric quantity of each electric core and the real-time electric quantity of the battery pack in a static state; searching the relationship table of aging degree, battery temperature, open circuit voltage and electric quantity SOC n value at different time in the charging process, selecting different charging rates for charging by searching the best charging rate relationship table of the electric core at different temperatures and electric quantities according to the electric quantity of the battery pack at the end time of the charging process estimated by ampere-hour integral, and correcting the capacity of the battery pack and stopping charging, thereby improving the problems of early ending or not fully charging of the battery pack.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy power battery, and particularly relates to a capacity correction method of a battery pack. BACKGROUND

[0002] The SOC of the battery, i.e. the state of charge, reflects the capacity of the battery, and since it cannot be directly measured, it can only be estimated by the battery terminal voltage, the charging and discharging current or the battery internal resistance. The battery SOC estimation strategy mainly includes the open circuit voltage method, the ampere-hour integration method, the artificial neural network method and the Kalman filter method. At present, the industry mainly adopts the ampere-hour integration method supplemented by the open circuit voltage method OCV correction, which can improve the estimation accuracy of the SOC at the end of charging and discharging, but this method is based on the premise that the consistency of each cell in the battery pack is good. If the consistency of each cell in the battery pack is poor after being used for a period of time, the voltage difference of the cells at the end of charging and discharging is enlarged, which will cause the SOC estimation error of the battery pack to become large, and the problems of insufficient charging or insufficient endurance are prone to occur.

[0003] Chinese patent application with publication number CN109239608A provides a method for real-time correction of lithium battery SOC-OCV curve, determines that the battery is in a stationary state, confirms the battery temperature, voltage, ampere-hour integration to obtain the state of charge of the lithium battery at the stationary time and the SOC-OCV curve, judges whether the lithium battery is full every certain period of time, if full, judges the error of the present state of charge according to the charged electric quantity, and corrects the SOC-OCV curve, but this method is not suitable for the case where the aging degrees of the multiple cells in the battery pack are inconsistent, because if the battery pack is charged with a certain current and charging time according to the highest capacity of the cells, the problem of early end of battery pack charging and insufficient charging of the battery pack capacity will exist. Therefore, it is necessary to provide a capacity correction method of a battery pack considering the differences of the cells. SUMMARY

[0004] Therefore, the present application provides a capacity correction method of a battery pack considering the differences of the cells.

[0005] The technical solution of the present application is realized as follows: the present application provides a capacity correction method of a battery pack, including the following steps:

[0006] Pre-test the cells to obtain the relationship table of the aging degree SOH of the cells at different times, the battery temperature T, the open circuit voltage U and the electric quantity SOC m m m m

[0007] ​​​​The battery pack of different temperatures and different aging degrees is subjected to a charging test in advance to obtain a relationship table of the aging degree SOH n , the battery temperature T n , the open circuit voltage U n and the power SOC n value at different moments in the charging process

[0008] The optimal charging rate relationship table of the battery cell under different temperatures and powers is obtained through test and calibration

[0009] The power of the battery pack in each static state is recorded to obtain the power SOC0 of each battery cell of the battery pack in the static state

[0010] The real-time power of each battery cell and the real-time power SOC P1 of the battery pack at the moment P1 in the current charging process are estimated through ampere-hour integration

[0011] The relationship table of the aging degree SOH n , the battery temperature T n , the open circuit voltage U n and the power SOC n value at different moments in the charging process is searched to obtain the theoretical power of each battery cell at the moment P1 in the current charging process and the theoretical power SOC' of the current battery pack P1

[0012] The power SOC P1 of the battery pack at the moment P1 in the charging process estimated through ampere-hour integration is charged at different charging rates by searching the optimal charging rate relationship table of the battery cell under different temperatures and powers, and the capacity of the battery pack is corrected and the charging is stopped

[0013] On the basis of the above technical scheme, preferably, the power of the battery pack in each static state is recorded to obtain the power SOC0 of each battery cell of the battery pack in the static state, which is obtained by using ampere-hour integration supplemented by OCV correction; and the maximum value and the minimum value are selected from the powers of the battery cells, and the power difference between the two is taken as the extreme value ΔSOC0 of the static power difference

[0014] Preferably, the real-time power of each battery cell and the real-time power SOC P1 of the battery pack at the moment P1 in the current charging process are estimated through ampere-hour integration, the real-time powers of each battery cell at the end of the current charging process are recorded as SOC C1 , SOC C2 , …, SOC Cn respectively; n is the number of battery cells; and the real-time power SOC P1 ​= (SOC C1 + SOC C2 + … + SOC Cn ) / n, select the maximum real-time capacity of the battery SOC max and the minimum real-time capacity of the battery SOC min , the extreme value of the real-time capacity difference is denoted as ΔSOC P1 = SOC max - SOC min .

[0015] Preferably, the relationship table of aging degree SOH n , battery temperature T n , open circuit voltage U n and capacity SOC n at different times during charging is searched to obtain the theoretical capacity of each battery at time P1 during the current charging process and the theoretical capacity SOC' of the current battery pack P1 , the theoretical capacity of each battery at time P1 during the current charging process is denoted as SOC' C1 , SOC' C2 , …, SOC' Cn ; the theoretical capacity SOC' of the current battery pack is denoted as P1 = (SOC' C1 + SOC' C2 + … + SOC' Cn ) / n, select the maximum theoretical capacity of the battery SOC' max and the minimum theoretical capacity of the battery SOC' min , the extreme value of the theoretical capacity difference is denoted as ΔSOC' P1 = SOC' max - SOC' min .

[0016] Preferably, the capacity SOC P1 of the battery pack at time P1 during the charging process estimated by ampere-hour integration is searched by searching the relationship table of the optimal charging rate of the battery at different temperatures and capacities, the charging is performed at different charging rates, the capacity of the battery pack is corrected and the charging is stopped, including the following contents:

[0017] Set the first capacity threshold and the second capacity threshold; and set the first charge-discharge cycle threshold and the second charge-discharge cycle threshold of the battery pack;

[0018] A, the theoretical capacity SOC' of the battery pack at time P1 during the current charging process P1 < the first capacity threshold: it is considered that the theoretical capacity SOC' of the battery pack at time P1 during the current charging process P1 and the real-time capacity SOC of the current battery packP1 Accordingly, the optimal charging rate relationship table of the battery cell at different temperatures and electric quantities is searched to obtain the real-time electric quantity SOC of the battery pack at the time P1 in the charging process P1 The corresponding charging rate is used for charging;

[0019] B, the first capacity threshold value ≤ the theoretical electric quantity SOC of the battery pack at the time P1 in the charging process P1 <Second capacity threshold value: the real-time electric quantity SOC of the battery pack at the time P1 in the charging process is obtained by the ampere-hour integral estimation P1 And the real-time electric quantity difference extreme value ΔSOC P1 Referring to the electric quantity SOC0 of each battery cell and the extreme value ΔSOC0 of the static electric quantity when the battery pack is last static, the charging strategy is as follows:

[0020] B1: If the charge-discharge cycle number of the battery pack < the first charge-discharge cycle number threshold value, when ΔSOC P1 > ΔSOC0 + A, the real-time electric quantity SOC of the battery cell at the time P1 in the charging process is used max The corresponding charging rate in the optimal charging rate relationship table of the battery cell at different temperatures and electric quantities is used for charging; when ΔSOC P1 < ΔSOC0 + A, the real-time electric quantity SOC of the battery pack at the time P1 in the current charging process is used P1 The corresponding charging rate in the optimal charging rate relationship table of the battery cell at different temperatures and electric quantities is used for charging; A is a constant;

[0021] B2: If the first charge-discharge cycle number threshold value ≤ the charge-discharge cycle number of the battery pack < the second charge-discharge cycle number threshold value, when ΔSOC P1 > ΔSOC0 + B, the real-time electric quantity SOC of the battery cell at the time P1 in the charging process is used max The corresponding charging rate in the optimal charging rate relationship table of the battery cell at different temperatures and electric quantities is used for charging; when ΔSOC P1 < ΔSOC0 + B, the real-time electric quantity SOC of the battery pack at the time P1 in the current charging process is used P1 The corresponding charging rate in the optimal charging rate relationship table of the battery cell at different temperatures and electric quantities is used for charging; B is a constant;

[0022] B3: If the charge-discharge cycle number of the battery pack ≥ the second charge-discharge cycle number threshold value, when ΔSOC P1 > ΔSOC0 + C, the real-time electric quantity SOC of the battery cell at the time P1 in the charging process is used max The corresponding charging rate in the optimal charging rate relationship table of the battery cell at different temperatures and electric quantities is used for charging; when ΔSOCP1 When SOC < 0+C, the real-time SOC of the battery pack at time P1 during the current charging process is used. P1 Charge the battery at the current temperature according to the optimal charging rate relationship table for different temperatures and capacities of the battery cell; C is a constant.

[0023] C. Real-time SOC of the battery pack at point P1 during the charging process. P1 When the second capacity threshold is reached, the state of charge (SOC) of the battery pack at time P1 during the charging process, which is estimated by ampere-hour integral, is obtained. P1 Extreme value of the difference between real-time power consumption and ΔSOC P1 ; and by querying the aging level (SOH) at different times during the charging process. n Battery temperature T n Open circuit voltage U n With SOC n The relationship table of values ​​is used to obtain the theoretical SOC' of the current battery pack. P1 The extreme value of the difference between the theoretical and theoretical charge values, ΔSOC' P1 ;

[0024] C1: If the number of charge / discharge cycles of the battery pack is less than the threshold for the first charge / discharge cycle, when ΔSOC P1 >△SOC' P1 During step +D, the SOC of the cell with the highest real-time charge at time P1 during the charging process is used. max Charge the battery at the optimal charging rate corresponding to the current temperature in the table of optimal charging rates for different temperatures and capacities of the battery cell; when ΔSOC P1 <△SOC' P1 When +D is applied, the real-time SOC of the battery pack at time P1 during the current charging process is calculated. P1 Adjust to 100% and stop charging; D is a constant;

[0025] C2: If the first charge / discharge cycle threshold is less than the battery pack's charge / discharge cycle count, and the second charge / discharge cycle threshold is less than the second charge / discharge cycle count, then when ΔSOC... P1 >△SOC' P1 During step +E, the cell with the highest real-time charge level at time P1 in the charging process is used. max Charge the battery at the optimal charging rate corresponding to the current temperature in the table of optimal charging rates for different temperatures and capacities of the battery cell; when ΔSOC P1 <△SOC' P1 When +E is applied, the real-time SOC of the battery pack at time P1 during the current charging process is displayed. P1 Adjust to 100% and stop charging; E is a constant;

[0026] C3: If the number of charge / discharge cycles of the battery pack is greater than or equal to the second charge / discharge cycle threshold, when ΔSOC P1 >△SOC' P1 When +F is applied, the cell with the highest real-time charge level at time P1 during the charging process is used. max Charge the battery at the optimal charging rate corresponding to the current temperature in the table of optimal charging rates for different temperatures and capacities of the battery cell; when ΔSOC P1 <△SOC' P1 When +F is applied, the real-time SOC of the battery pack at time P1 during the current charging process will be displayed. P1 Adjust to 100% and stop charging; F is a constant.

[0027] Preferably, the first capacity threshold is 90-95% of the rated capacity of the cell or battery pack; the second capacity threshold is 98%-99% of the rated capacity of the cell or battery pack.

[0028] Preferably, the first charge-discharge cycle threshold is 500 times; the second charge-discharge cycle threshold is 1000 times.

[0029] Preferably, constant A is 0.5%, constant B is 1%, constant C is 1.5%, constant D is 0.1%, constant E is 0.2%, and constant F is 0.3%.

[0030] The battery pack capacity correction method provided by this invention has the following advantages compared with the prior art:

[0031] (1) This solution takes into account the different aging and capacity change trends of different cells. It uses the real-time power of the battery pack and the theoretical power of the current battery pack to observe the power difference of each cell in the battery pack. By using the difference between the two, a suitable charging rate is selected to charge the cells and the battery pack. The battery pack can be charged with more power, which improves the problem of premature battery pack charging and insufficient battery pack capacity. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart of a battery pack capacity correction method according to the present invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0035] The technical solutions of the present application are implemented as follows: Figure 1 As shown in the figure, the present application provides a capacity correction method of a battery pack, comprising the following steps:

[0036] S1: Pre-test the static test of the battery cell to obtain the relationship table of the aging degree SOH m , battery temperature T m , open circuit voltage U m and power SOC m at different times.

[0037] S2: Pre-test the charging test of the battery pack with different temperatures and different aging degrees to obtain the relationship table of the aging degree SOH n , battery temperature T n , open circuit voltage U n and power SOC n at different times during the charging process.

[0038] S3: Through test and calibration, the optimal charging rate relationship table of the battery cell under different temperatures and powers is obtained; as shown in Table 1 below, the power of the battery cell here refers to the rated power, for example, if the current power is within the interval of two adjacent end points, the charging rate of the previous end point is used for charging, for example, if the power of the battery cell is 15%, the optimal charging rate at 25℃ is 0.8C.

[0039] Table 1

[0040]

[0041] S4: Record the power of the battery pack at each static state to obtain the power SOC0 of each battery cell of the battery pack in the static state.

[0042] Specifically, the power SOC0 of each battery cell is obtained by using ampere-hour integration assisted by OCV correction; and the maximum value and the minimum value are selected from the power of each battery cell, and the power difference between the two is taken as the extreme value of the static power difference SOC0. Here, the OCV correction is to use the aging degree SOH m , battery temperature T m , open circuit voltage U m and power SOC mThe relationship table is used to correct the SOC0 of each battery cell after the ampere-hour integration. The correction process is as follows: an estimated value of the current battery cell is estimated by ampere-hour integration, and a table lookup value is obtained by table lookup. When the difference between the two is large, the table lookup value is used to replace the estimated value.

[0043] S5: The real-time capacity of each battery cell and the real-time capacity of the battery pack SOC P1 at the time P1 in the current charging process are estimated by ampere-hour integration.

[0044] Specifically, the real-time capacity of each battery cell at the end of the current charging process is recorded as SOC C1 , SOC C2 , …, SOC Cn ; n is the number of battery cells; the real-time capacity of the battery pack at the time P1 in the current charging process is SOC P1 = (SOC C1 + SOC C2 + … + SOC Cn ) / n; the battery cell with the largest real-time capacity SOC max and the battery cell with the smallest real-time capacity SOC min are selected, and the extreme value of the real-time capacity difference is recorded as ΔSOC P1 = SOC max - SOC min .

[0045] S6: The relationship table of the aging degree SOH n , the battery temperature T n , the open-circuit voltage U n , and the capacity SOC n at different times in the charging process is searched to obtain the theoretical capacity of each battery cell at the time P1 in the current charging process and the theoretical capacity of the current battery pack SOC’ P1 .

[0046] Specifically, the theoretical capacity of each battery cell at the time P1 in the current charging process is recorded as SOC’ C1 , SOC’ C2 , …, SOC’ Cn ; the theoretical capacity of the current battery pack is SOC’ P1 = (SOC’ C1 + SOC’ C2 + … + SOC’ Cn ) / n; the battery cell with the largest theoretical capacity SOC’ max and the battery cell with the smallest theoretical capacity SOC’ min are selected, and the extreme value of the theoretical capacity difference is recorded as ΔSOC’ P1 = SOC’ max - SOC’ min .

[0047] S7: SOC of the battery pack at time P1 during the charging process, estimated by ampere-hour integration. P1 By looking up the optimal charging rate relationship table of the battery cells under different temperatures and capacities, different charging rates are selected for charging, and the capacity of the battery pack is adjusted before charging is stopped.

[0048] Step S7 specifically includes the following:

[0049] A first capacity threshold and a second capacity threshold are set. The first capacity threshold is 90-95% of the rated capacity of the cell or battery pack, preferably 95%. The second capacity threshold is 98%-99% of the rated capacity of the cell or battery pack, preferably 99%. A first charge-discharge cycle number threshold and a second charge-discharge cycle number threshold are also set for the battery pack. The first charge-discharge cycle number threshold is preferably 500 times, and the second charge-discharge cycle number threshold is preferably 1000 times.

[0050] A. The theoretical SOC' of the battery pack at time P1 during the current charging process. P1 When the first capacity threshold is reached: the theoretical SOC of the battery pack at time P1 during the current charging process is considered to be... P1 With the current battery pack's real-time state of charge (SOC) P1 Similarly, find the optimal charging rate relationship table for the battery cells under different temperatures and capacities, based on the current real-time SOC of the battery pack. P1 Charge at the corresponding charging rate;

[0051] B. The theoretical SOC' of the battery pack at time P1 during the charging process is less than or equal to the first capacity threshold. P1 <At the second capacity threshold: the real-time SOC of the battery pack at moment P1 during the charging process, based on the ampere-hour integral estimation. P1 Extreme value of the difference between real-time power consumption and ΔSOC P1 Referring to the extreme value ΔSOC0 of the SOC0 of each cell during the most recent period when the battery pack was idle and the difference between the idle SOC0 and the SOC0, the charging strategy is as follows:

[0052] B1: If the number of charge / discharge cycles of the battery pack is less than the threshold for the first charge / discharge cycle, when ΔSOC P1 When >△SOC0+A, the SOC of the cell with the highest real-time charge at time P1 during the charging process is used. max Charge the battery at the optimal charging rate corresponding to the current temperature in the table of optimal charging rates for different temperatures and capacities of the battery cell; when ΔSOC P1 When the SOC is less than △SOC0+A, the real-time SOC of the battery pack at time P1 during the current charging process is used. P1Charging at the charging rate corresponding to the current temperature in the optimal charging rate relationship table of the battery cell under different temperatures and electric quantities; A is a constant;

[0053] B2: If the first charge-discharge cycle threshold ≤ the charge-discharge cycle number of the battery pack < the second charge-discharge cycle threshold, when △SOC P1 >△SOC0+B, the SOC of the cell with the maximum real-time electric quantity at time P1 in the charging process is adopted max Charging at the charging rate corresponding to the current temperature in the optimal charging rate relationship table of the battery cell under different temperatures and electric quantities; when △SOC P1 <△SOC0+B, the real-time electric quantity SOC of the battery pack at time P1 in the current charging process is adopted P1 Charging at the charging rate corresponding to the current temperature in the optimal charging rate relationship table of the battery cell under different temperatures and electric quantities; B is a constant;

[0054] B3: If the charge-discharge cycle number of the battery pack ≥ the second charge-discharge cycle threshold, when △SOC P1 >△SOC0+C, the SOC of the cell with the maximum real-time electric quantity at time P1 in the charging process is adopted max Charging at the charging rate corresponding to the current temperature in the optimal charging rate relationship table of the battery cell under different temperatures and electric quantities; when △SOC P1 <△SOC0+C, the real-time electric quantity SOC of the battery pack at time P1 in the current charging process is adopted P1 Charging at the charging rate corresponding to the current temperature in the optimal charging rate relationship table of the battery cell under different temperatures and electric quantities; C is a constant;

[0055] C, the real-time electric quantity SOC of the battery pack at time P1 in the charging process P1 ≥ the second capacity threshold, the electric quantity SOC of the battery pack at time P1 in the charging process obtained by the ampere-hour integral estimation P1 And the real-time electric quantity difference extreme value △SOC P1 ; and by querying the relationship table of aging degree SOH n , battery temperature T n , open circuit voltage U n and electric quantity SOC n value, the theoretical electric quantity SOC' P1 and the extreme value of the theoretical electric quantity difference △SOC' P1 of the current battery pack are obtained;

[0056] C1: If the charge-discharge cycle number of the battery pack < the first charge-discharge cycle threshold, when △SOC P1 >△SOC' P1SOC of the battery pack at time P1 in the current charging process max Charging at the charging rate corresponding to the current temperature in the optimal charging rate relation table of the battery cells under different temperatures and electric quantities; when△SOC P1 <△SOC’ P1 SOC of the battery pack at time P1 in the current charging process P1 is corrected to 100%, and the charging is stopped; D is a constant.

[0057] C2: If the first charge-discharge cycle threshold ≤ the charge-discharge cycle number of the battery pack < the second charge-discharge cycle threshold, when△SOC P1 >△SOC’ P1 SOC of the battery cell with the largest real-time electric quantity at time P1 in the charging process max Charging at the charging rate corresponding to the current temperature in the optimal charging rate relation table of the battery cells under different temperatures and electric quantities; when△SOC P1 <△SOC’ P1 SOC of the battery pack at time P1 in the current charging process P1 is corrected to 100%, and the charging is stopped; E is a constant.

[0058] C3: If the charge-discharge cycle number of the battery pack ≥ the second charge-discharge cycle threshold, when△SOC P1 >△SOC’ P1 SOC of the battery cell with the largest real-time electric quantity at time P1 in the charging process max Charging at the charging rate corresponding to the current temperature in the optimal charging rate relation table of the battery cells under different temperatures and electric quantities; when△SOC P1 <△SOC’ P1 SOC of the battery pack at time P1 in the current charging process P1 is corrected to 100%, and the charging is stopped; F is a constant.

[0059] It can be seen that in case A, the battery pack is far from being full, and the difference between the real-time electric quantity and the theoretical electric quantity is small; in case B, according to the different charge-discharge cycle numbers of the battery pack, the extreme value△SOC0 of the last standing electric quantity difference is used to measure whether the capacity difference of each battery cell in the battery pack at time P1 in the current charging process is significant; in case C, the extreme value△SOC’ P1 of the theoretical electric quantity difference is used to measure whether the capacity difference of each battery cell in the battery pack at time P1 in the current charging process is significant.

[0060] In the above steps, the constant A is 0.5%, the constant B is 1%, the constant C is 1.5%; the constant D is 0.1%, the constant E is 0.2%, and the constant F is 0.3%.

[0061] Here, the number of charge-discharge cycles of the battery pack is calculated by using an accumulation scheme:

[0062] N=K1X1+K2X2+K3X3; wherein N is the number of charge-discharge cycles of the battery pack; X1 is the number of times that the remaining capacity at the start of charging of the battery pack reaches 20% or less of the rated capacity of the battery pack, X2 is the number of times that the remaining capacity at the start of charging of the battery pack reaches the interval (20%, 90%) of the rated capacity of the battery pack; X3 is the number of times that the remaining capacity at the start of charging of the battery pack reaches 90% or more of the rated capacity of the battery pack; K1, K2 and K3 are weights, K1=1, K2=0.5*(0.9-M) / 0.7; K3=0.15(0.1-M) / 0.1. M is the percentage of the remaining capacity at the start of charging of the battery pack to the rated capacity.

[0063] To verify the actual effect of the present scheme, the conventional charging method and the method of the present application were verified at an initial temperature of 0°C and 40°C, respectively, and the verification results are shown in Tables 2 and 3. ℃

[0064]

[0065] Table 2 0°C charging verification

[0066]

[0067] Table 3 40°C charging verification

[0068] From the above table, even if the initial capacity of the battery pack is consistent, the extreme value of the static charge difference of each cell in the battery pack is small, and no matter the environmental temperature, the amount of electricity charged to full by the present method is obviously increased compared with the conventional charging method, which proves that the present scheme can charge more electricity and improves the problem of early end of battery pack charging and insufficient capacity of the battery pack.

[0069] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A capacity correction method of a battery pack, characterized by, Comprising the following steps: S1: pre-test the battery cell for static test, obtain the aging degree SOH of the battery cell at different time m , battery temperature T m , open circuit voltage U m and the relationship table of power SOC m ; S2: pre-charging test on battery packs of different temperatures and different aging degrees to obtain the relationship table of aging degree SOH at different time in the charging process n , battery temperature T n , open circuit voltage U n and power SOC n value S3: Through test and calibration, the best charging rate relationship table of the battery cell at different temperatures and electric quantities is obtained; S4: record the battery pack power at each time of static state, obtain the battery pack of each cell SOC0 in static state; using the ampere-hour integral supplemented by OCV correction to obtain the SOC0 of each cell; and select the maximum and minimum from the power of each cell, and the difference between the two is the extreme value of the static power difference △SOC0; OCV correction is the aging degree SOH of the cell at different time obtained in step S1 m , battery temperature T m , open circuit voltage U m and the relationship table of power SOC m The power SOC0 of each cell after ampere-hour integration is corrected, and the correction process is: the estimated value of the estimated value of the current cell power is estimated by ampere-hour integration, and the table value is obtained by table lookup. When the difference between the two is large, replace the estimated value with the table value. S5: At the time P1 in the current charging process, the real-time power of each battery cell and the real-time power SOC of the battery pack are estimated by ampere-hour integration P1 , the real-time power of each battery cell at the time P1 in the current charging process is recorded as SOC C1 , SOC C2 , …, SOC Cn ; n is the number of battery cells; the real-time power SOC of the battery pack at the time P1 in the current charging process is recorded as SOC P1 = (SOC C1 + SOC C2 + … + SOC Cn ) / n, the battery cell with the maximum real-time power SOC max and the battery cell with the minimum real-time power SOC min are selected, and the real-time power difference extreme value is recorded as ΔSOC P1 =SOC max -SOC min ; S6: find the aging degree SOH at different time in the charging process n , battery temperature T n , open circuit voltage U n , and the relationship table of the value of the power SOC n , get the theoretical power of each battery cell at the time P1 in the current charging process and the theoretical power of the current battery pack SOC' P1 , the theoretical power of each battery cell at the time P1 in the current charging process is recorded as SOC' C1 , SOC' C2 , …, SOC' Cn ; the theoretical power of the current battery pack SOC' P1 = (SOC' C1 + SOC' C2 + … + SOC' Cn ) / n, select the battery cell with the largest theoretical power SOC' max and the battery cell with the smallest theoretical power SOC' min , the extreme value of the difference of the theoretical power is recorded as△SOC' P1 =SOC' max -SOC' min ; S7: the state of charge SOC of the battery pack at the time P1 in the charging process estimated by ampere-hour integration P1 , by looking up the optimal charging rate relationship table of the battery cell at different temperatures and states of charge, different charging rates are selected for charging, and the capacity of the battery pack is corrected and charging is stopped; a first capacity threshold and a second capacity threshold are set; and a first charge-discharge cycle threshold and a second charge-discharge cycle threshold of the battery pack are set; A. The theoretical SOC' of the battery pack at time P1 during the current charging process. P1 When the first capacity threshold is reached: the theoretical SOC of the battery pack at time P1 during the current charging process is considered to be... P1 With the current battery pack's real-time state of charge (SOC) P1 Similarly, find the optimal charging rate relationship table for the battery cells under different temperatures and capacities, based on the current real-time SOC of the battery pack. P1 Charge at the corresponding charging rate; B. First capacity threshold value ≤ theoretical capacity SOC' of battery pack at time P1 during charging process P1 <Second capacity threshold value: real-time capacity SOC of battery pack at time P1 during charging process estimated by ampere-hour integral P1 And real-time capacity difference extreme value ΔSOC P1 Referring to the capacity SOC0 of each cell and the extreme value ΔSOC0 of the static capacity difference of the battery pack at the last time, the charging strategy is as follows: B1: If the number of charge-discharge cycles of the battery pack < the first charge-discharge cycle threshold, when △SOC P1 >△SOC0+A, the real-time power of the cell SOC at time P1 in the charging process is adopted max Corresponding to the charging rate at the current temperature in the best charging rate relationship table of the cell at different temperatures and power, charge; when △SOC P1 <△SOC0+A, the real-time power of the battery pack SOC at time P1 in the current charging process is adopted P1 Corresponding to the charging rate at the current temperature in the best charging rate relationship table of the cell at different temperatures and power; A is a constant; B2: if the first charge-discharge cycle threshold ≤ the charge-discharge cycle number of the battery pack < the second charge-discharge cycle threshold, when △SOC P1 >△SOC0+B, the real-time power of the battery pack at P1 in the charging process is adopted max Corresponding to the charging rate at the current temperature in the best charging rate relationship table of the battery at different temperatures and power, the battery is charged; when △SOC P1 <△SOC0+B, the real-time power of the battery pack at P1 in the charging process is adopted P1 Corresponding to the charging rate at the current temperature in the best charging rate relationship table of the battery at different temperatures and power, the battery is charged; B is a constant; B3: If the number of charge-discharge cycles of the battery pack ≥ the second charge-discharge cycle threshold, when △SOC P1 SOC of the cell with the largest real-time power at time P1 in the charging process max corresponding to the charging rate at the current temperature in the best charging rate relationship table of the cell at different temperatures and power, and charging; when △SOC P1 <△SOC0+C, the real-time power SOC of the battery pack at time P1 in the current charging process is adopted P1 corresponding to the charging rate at the current temperature in the best charging rate relationship table of the cell at different temperatures and power, and charging; C is a constant; C. real-time capacity SOC of the battery pack at time P1 during charging P1 ≥ second capacity threshold value, the capacity SOC of the battery pack at time P1 during charging obtained by the ampere-hour integral estimation P1 and the real-time capacity difference extreme value ΔSOC P1 ; and by querying the relationship table of the aging degree SOH n , the battery temperature T n , the open circuit voltage U n and the capacity SOC n value, obtaining the theoretical capacity SOC' P1 and the theoretical capacity difference extreme value ΔSOC' P1 of the current battery pack; C1: if the number of charge-discharge cycles of the battery pack < the first charge-discharge cycle threshold, when △SOC P1 >△SOC’ P1 +D, the real-time power of the cell SOC max of the time P1 in the charging process is adopted to charge; when △SOC P1 <△SOC’ P1 +D, the real-time power SOC P1 of the battery pack at the time P1 in the current charging process is corrected to 100%, and the charging is stopped; D is a constant; C2: if the first charge-discharge cycle threshold value ≤ the charge-discharge cycle number of the battery pack < the second charge-discharge cycle threshold value, when △SOC P1 >△SOC’ P1 +E, the real-time power of the cell SOC max corresponding to the charge rate at the current temperature in the best charge rate relationship table of the cell at different temperatures and power is used for charging; when △SOC P1 <△SOC’ P1 +E, the real-time power SOC P1 of the battery pack at time P1 in the current charging process is corrected to 100%, and the charging is stopped; E is a constant; C3: if the number of charge-discharge cycles of the battery pack is greater than or equal to the second charge-discharge cycle threshold, when △SOC P1 P1 , the real-time power of the battery pack at time P1 in the charging process is corrected to 100%, and the charging is stopped; F is a constant. max The charging is performed at the charging rate corresponding to the current temperature in the optimal charging rate relationship table of the battery cell at different temperatures and power; when △SOC P1 P1 , the real-time power of the battery pack at time P1 in the current charging process is corrected to 100%, and the charging is stopped; F is a constant. P1 The charging is performed at the charging rate corresponding to the current temperature in the optimal charging rate relationship table of the battery cell at different temperatures and power; when △SOC P1 P1 , the real-time power of the battery pack at time P1 in the current charging process is corrected to 100%, and the charging is stopped; F is a constant.

2. The capacity correction method of a battery pack according to claim 1, characterized by, The first capacity threshold is 90-95% of the rated capacity of the battery cell or battery pack; and the second capacity threshold is 98-99% of the rated capacity of the battery cell or battery pack.

3. The method of claim 1, wherein, The first charge-discharge cycle number threshold is 500 times; and the second charge-discharge cycle number threshold is 1000 times.

4. The method of claim 1, wherein, The constant A is 0.5%, the constant B is 1%, the constant C is 1.5%, the constant D is 0.1%, the constant E is 0.2%, and the constant F is 0.3%.

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