Method for predicting battery pack system capacity, electronic device, and storage medium

Abstract

The application provides a battery pack system capacity prediction method, an electronic device and a storage medium. The prediction method comprises the following steps: obtaining a first capacity minimum value of all battery cells in a to-be-tested battery pack; and determining a capacity prediction value of the to-be-tested battery pack according to a preset relationship between the first capacity minimum value and a first discharge temperature rise value, a first discharge capacity difference value and the capacity prediction value of the to-be-tested battery pack. The battery pack system capacity prediction method provided by the application solves the problems of long test time and high production cost caused by the existing full-test battery pack system capacity.

Description

Technical Field

[0001] This invention relates to the field of automotive power battery technology, and in particular to a method for predicting the capacity of a battery pack system, an electronic device, and a storage medium. Background Technology

[0002] With the rapid development of new energy vehicles and the promising market prospects, more and more car companies are focusing on the development of this field. Among them, the cost, safety, efficiency and intelligence of new energy vehicles are of paramount importance, and these are all closely related to the development of new energy power batteries.

[0003] As the core power source of new energy vehicles, the battery pack is a key component restricting the development of new energy vehicles, and its system capacity directly affects the driving range of new energy vehicles. In order to ensure the high performance of the battery pack, the testing of the battery pack, especially the testing of the battery pack system capacity, is particularly important.

[0004] Currently, the main method for testing the system capacity of battery packs is the full charge and full discharge method. The testing process is simple, but it is time-consuming. Taking the 1C constant current test rate as an example, a single test of a single battery pack takes about 5 hours. With multiple tests, the test time will increase exponentially, which is too time-consuming.

[0005] The development of new energy vehicles is rapid and the demand is increasing. If the system capacity of every battery pack is fully tested, firstly, the testing time is long and equipment resources are limited, and secondly, the production and delivery pressure is huge and the production cost is high. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method, electronic device and storage medium for predicting the capacity of a battery pack system, in order to solve the problems of long testing time and high production cost caused by the existing full-capacity testing of battery pack systems.

[0007] To achieve the above and other related objectives, the present invention provides a method for predicting the capacity of a battery pack system, the prediction method comprising:

[0008] S1 obtains the first minimum capacity of all cells in the battery pack under test;

[0009] S2 determines the predicted capacity value of the battery pack under test based on a preset relationship between the first minimum capacity value and the first discharge temperature rise value, the first discharge capacity difference value, and the predicted capacity value of the battery pack under test.

[0010] Optionally, the preset relationship satisfies the correction formula y = x1 + x2 * k - x3 + Δ, where y is the predicted capacity of the battery pack under test, x1 is the first minimum capacity, x2 is the first discharge temperature rise, k is the temperature influence coefficient of the battery pack under test, x3 is the first discharge capacity difference, and Δ is the capacity compensation value of the battery pack under test.

[0011] Optionally, before step S2, the following may also be included:

[0012] S21 obtains the second minimum capacity of all cells in the sample battery pack;

[0013] S22 performs charge and discharge tests on the sample battery pack to obtain the discharge capacity value, discharge temperature value, and second discharge capacity difference value.

[0014] S23 corrects the second minimum capacity value based on the second discharge temperature rise value and the second discharge capacity difference of the sample battery pack, and obtains the initial formula y'=x1'+x2'*k-x3', and thus obtains the initial value of the capacity prediction of the sample battery pack, where y' is the initial value of the capacity prediction of the sample battery pack, x1' is the second minimum capacity value, x2' is the second discharge temperature rise value and x2'=discharge temperature value-initial temperature value, and x3' is the second discharge capacity difference;

[0015] S24 repeats S21-S23 to obtain the discharge capacity value and initial capacity prediction value of several sample battery packs, and obtains the capacity compensation value by linear fitting the two.

[0016] S25 obtains the first discharge temperature rise value based on the second discharge temperature rise value of several sample battery packs, obtains the first discharge capacity difference value based on the second discharge capacity difference value of several sample battery packs, and compensates the initial formula based on the capacity compensation value, finally obtaining the corrected formula y=x1+x2*k-x3+Δ.

[0017] Optionally, the method for performing charge-discharge tests on the sample battery pack includes:

[0018] S221 After the sample battery pack is left to stand for a time T1, it is charged with a constant current of I1 until the voltage of the sample battery pack reaches the upper limit voltage.

[0019] S222 After the sample battery pack is left to stand for a time T2, it is charged with a constant current of I2 until the voltage of the sample battery pack reaches the upper limit voltage.

[0020] S223 After the sample battery pack is left to stand for a time T3, it is charged with a constant current of I3 until the voltage of the sample battery pack reaches the upper limit voltage.

[0021] S224 After the sample battery pack is left to stand for T4 time, it is discharged at a constant current of I4 until the voltage of the sample battery pack reaches the lower limit voltage, thereby obtaining the discharge capacity value, discharge temperature value and second discharge capacity difference value of the sample battery pack.

[0022] Among them, I3 <I2<I1=I4,T1=T2=T3<T4。

[0023] Optionally, after step S224, the method further includes: S225, after the sample battery pack has been left to stand for a time T5, using the voltage difference of the recovery of all cells in the sample battery pack to determine the consistency of all cells in the sample battery pack.

[0024] Optionally, I1 = I4 = 1 / 3C, I2 = 0.2C, I3 = 0.1C, where C is the nominal capacity; T1 = T2 = T3 ≥ 30s, T4 ≥ 30min, T5 > 0.

[0025] Optionally, prior to step S1, the prediction method further includes:

[0026] Based on the SOC of all cells in the battery pack under test, and the voltage difference and tolerance between any two cells, determine whether the cells in the battery pack under test meet the consistency requirements.

[0027] Alternatively, based on the internal resistance, SOC, and voltage difference and tolerance between any two cells in the battery pack under test, it can be determined whether the cells in the battery pack under test meet the consistency requirements.

[0028] If it is determined that the cells in the battery pack under test meet the consistency requirements, then step S1 is executed.

[0029] Optionally, S1 further includes the step of obtaining the first maximum capacity of all cells in the battery pack under test; in this case, the prediction method further includes:

[0030] S3 verifies the predicted capacity of the battery pack under test based on the first minimum capacity and the first maximum capacity. If the predicted capacity of the battery pack under test is between the first minimum capacity and the first maximum capacity, the verification passes; otherwise, the verification fails.

[0031] The present invention also provides an electronic device comprising: a memory and a processor, the memory for storing a computer program, and the processor for executing the computer program stored in the memory to cause the electronic device to perform the battery pack system capacity prediction method as described in any of the preceding claims.

[0032] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for predicting the capacity of a battery pack system as described in any of the preceding claims.

[0033] As described above, the battery pack system capacity prediction method, electronic device, and storage medium of the present invention, based on a preset relationship between the first minimum capacity value, the first discharge temperature rise value, the first discharge capacity difference value, and the capacity prediction value in the battery pack under test, correct the first minimum capacity value using the first discharge temperature rise value and the first discharge capacity difference value. Thus, the system capacity can be predicted using only the minimum capacity value of all cells in the battery pack, enabling the produced battery pack to quickly predict the system capacity using the cell capacity, improving the battery pack testing efficiency and reducing production costs. Attached Figure Description

[0034] Figure 1 The flowchart shown is a process for predicting the capacity of a battery pack system according to the present invention.

[0035] Figure 2 The flowchart shown is a process for obtaining the modified formula according to the present invention.

[0036] Figure 3 The diagram shown is a structural schematic of the electronic device of the present invention. Detailed Implementation

[0037] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] Please see Figures 1 to 3 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation, the shape, quantity and proportion of each component in the actual implementation can be arbitrarily changed, and the layout of the components may also be more complex.

[0039] like Figure 1 As shown, this embodiment provides a method for predicting the capacity of a battery pack system. The method includes steps S1 and S2. This prediction method can be executed by an electronic device, such as a computer; however, other entities capable of executing this prediction method are also applicable to this embodiment, and no limitation is made. The following description uses a computer as the execution entity as an example:

[0040] Step S1: Obtain the first minimum capacity of all cells in the battery pack under test.

[0041] The battery pack under test is assembled from several battery cells. This application does not limit the assembly method of the battery pack under test. For example, the battery pack under test can be assembled directly from battery cells, or it can be assembled from battery cells into battery modules and then assembled from battery modules.

[0042] The capacity data of all cells in the battery pack under test can be obtained directly from the cell traceability system, which can be an MES management system, and the first minimum capacity value is determined from the capacity data of all cells in the battery pack under test.

[0043] In one possible implementation, before step S1, the prediction method further includes step S0: determining whether the cells in the battery pack under test meet the consistency requirements. If the cells in the battery pack under test meet the consistency requirements, then step S1 is continued; otherwise, if the cells in the battery pack under test do not meet the consistency requirements, then the battery pack under test is replaced and step S0 is re-executed.

[0044] This application does not limit the specific implementation method for determining whether the cells in the battery pack under test meet the consistency requirements. For example, the consistency requirements can be determined based on the SOC (state of charge) of all cells in the battery pack under test, as well as the voltage difference and tolerance between any two cells. For instance, if all cells have the same SOC, the voltage difference between any two cells is ≤10mV, and the tolerance is ≤3%, then the cells in the battery pack under test are determined to meet the consistency requirements, and step S1 is executed. Otherwise, if the cells in the battery pack under test do not meet the consistency requirements, the battery pack under test is replaced, and step S0 is executed again.

[0045] For example, the consistency requirements of the cells in the battery pack under test can be determined based on the internal resistance and state of charge (SOC) of all cells in the battery pack, as well as the voltage difference and tolerance between any two cells in the battery pack. For instance, if the internal resistance of all cells in the battery pack is ≤0.2mΩ, the SOC of all cells is consistent, and the voltage difference between any two cells in the battery pack is ≤10mV and the tolerance is ≤3%, then the cells in the battery pack are determined to meet the consistency requirements, and step S1 is executed. Conversely, if the cells in the battery pack are determined not to meet the consistency requirements, the battery pack under test is replaced, and step S0 is executed again. This embodiment is merely an example and is not limited to this.

[0046] In practical applications, in order to minimize the impact of process errors on cell performance, cells of the same grade and batch are generally selected for consistency assessment.

[0047] Since the production and testing of battery cells are managed systematically, the data from each battery cell's production and testing are uploaded to a system, such as a battery cell traceability system. The voltage, capacity, internal resistance, SOC, and other data of the battery cells involved in this application embodiment can be directly obtained from the battery cell traceability system, avoiding the time spent on retesting.

[0048] Step S2: Determine the predicted capacity value of the battery pack under test based on the preset relationship between the first minimum capacity value, the first discharge temperature rise value, the first discharge capacity difference value, and the predicted capacity value of the battery pack under test.

[0049] After determining the specifications and type of the battery pack under test, a preset relationship between the predicted capacity and the minimum capacity can be determined using the first discharge temperature rise and the first discharge capacity difference. This application does not limit the specific expression of the preset relationship; for example, it can be expressed using formulas, tables, etc. The predicted capacity is positively correlated with the first discharge temperature rise and negatively correlated with the first discharge capacity difference. The minimum capacity is corrected using the first discharge temperature rise and the first discharge capacity difference to determine the predicted capacity, ensuring its accuracy.

[0050] In one possible implementation, the preset relationship could be, for example, multiplying the first minimum capacity value by a first preset coefficient, increasing the first discharge temperature rise value by a second preset coefficient multiple, and subtracting the first discharge capacity difference value by a third preset coefficient multiple to obtain the predicted capacity value of the battery pack under test; or, for another example, multiplying the first minimum capacity value by a first preset coefficient, increasing the first discharge temperature rise value by a second preset coefficient multiple, and subtracting the first discharge capacity difference value by a third preset coefficient multiple, then compensating for the difference, and finally obtaining the predicted capacity value of the battery pack under test.

[0051] In this application embodiment, regarding the determination of the first discharge temperature rise value and the first discharge capacity difference of the battery pack under test in a preset relationship, one possible implementation is to perform charge-discharge tests on sample battery packs of the same specifications and type as the battery pack under test, and store the second discharge temperature rise value and the second discharge capacity difference of the sample battery packs determined after the charge-discharge tests of each specification and type of sample battery pack in memory or upload them to the cell traceability system. Then, based on the specifications and type of the battery pack under test, the second discharge temperature rise value and the second discharge capacity difference of the sample battery packs of the same specifications and type are retrieved from memory or the cell traceability system and used as the first discharge temperature rise value and the first discharge capacity difference of the battery pack under test, respectively.

[0052] The first discharge temperature rise of the battery pack under test refers to the difference between the discharge temperature and the initial temperature of the battery pack. Since the battery pack includes multiple cells, the discharge temperatures of these cells may differ. The discharge temperature of the battery pack can be the average of the discharge temperatures of the multiple cells. In other possible implementations, the median, maximum, or minimum discharge temperatures of the multiple cells can also be used as the discharge temperature of the battery pack. The initial temperature of the battery pack can be the ambient temperature before the discharge test, or the average temperature of the multiple cells before the discharge test. This embodiment is only an example and is not limited to this.

[0053] The first discharge capacity difference of the battery pack under test can be the capacity difference between the upper limit voltage and the minimum discharge end voltage of the battery pack under test, and the capacity difference between the upper limit voltage and the average discharge end voltage. The embodiments of this application are not limited to this. In other possible implementations, it can also be other forms, such as the capacity difference between the upper limit voltage and the minimum discharge end voltage of the battery pack under test, and the capacity difference between the upper limit voltage and the median discharge end voltage.

[0054] The second discharge temperature rise value and the first discharge temperature rise value have the same form of expression, and the second discharge capacity difference value and the first discharge capacity difference value have the same form of expression. Therefore, the first discharge temperature rise value and the first discharge capacity difference value have different forms of expression, which may also lead to certain deformations in the specific relationship of the preset relationship. The embodiments of this application will not be described in detail here.

[0055] To more clearly express the preset relationship, in one possible implementation, the preset relationship satisfies the correction formula y = x1 + x2 * k - x3 + Δ, where y is the predicted capacity of the battery pack under test, x1 is the first minimum capacity, x2 is the first discharge temperature rise, k is the temperature influence coefficient of the battery pack under test, x3 is the first discharge capacity difference, and Δ is the capacity compensation value of the battery pack under test.

[0056] In one possible implementation, the correction formula can be stored in the system. According to the specifications and type of the battery pack under test, the correction formula corresponding to the specifications and type can be directly called. In the formula, x2, k, x3 and Δ are all known fixed values.

[0057] In another possible implementation, a preset relationship between the battery packs under test can be determined by testing several sample battery packs. For example... Figure 2 As shown, the method for obtaining the corrected formula includes steps S21, S22, S23, S24, and S25.

[0058] Step S21: Obtain the second minimum capacity of all cells in the sample battery pack.

[0059] The capacity data of all cells in the sample battery pack can be obtained directly from the cell traceability system, and the second minimum capacity value is determined from the capacity data of all cells in the sample battery pack.

[0060] In one possible implementation, before performing step S21, the method further includes step S20, which is the step of determining the consistency of the cells in the sample battery pack. For the specific determination method, please refer to the introduction of the cell consistency determination method in the battery pack under test above, which will not be repeated here.

[0061] The sample battery pack and the battery pack under test are battery packs of the same specifications and type. Furthermore, the sample battery pack and the battery pack under test are battery packs made from the same batch of cells produced in the same grade and batch.

[0062] Step S22: Perform charge and discharge tests on the sample battery pack to obtain the discharge capacity value, discharge temperature value, and second discharge capacity difference value.

[0063] The method for charging and discharging a sample battery pack in this application embodiment is not specifically limited. In one possible implementation, the method for charging and discharging a sample battery pack includes steps S221, S222, S223 and S224.

[0064] Step S221: After the sample battery pack is left to stand for a time T1, it is charged with a constant current of I1 until the voltage of the sample battery pack reaches the upper limit voltage.

[0065] Since the initial voltages of the cells in the sample battery pack are not exactly the same, when the sample battery pack is charged with constant current, the voltage of the sample battery pack is considered to have reached the upper limit voltage as soon as the voltage of one of the cells reaches the upper limit voltage, and charging is stopped at this time.

[0066] Step S222: After the sample battery pack is left to stand for time T2, it is charged with a constant current of I2 until the voltage of the sample battery pack reaches the upper limit voltage.

[0067] Step S223: After the sample battery pack is left to stand for time T3, it is charged with a constant current of I3 until the voltage of the sample battery pack reaches the upper limit voltage.

[0068] After the voltage of the sample battery pack reaches the upper limit voltage, the sample battery pack is left standing for a period of time, and the voltage of the sample battery pack will drop. Therefore, continuing to charge the sample battery pack with reduced current will make the voltage of the sample battery pack more saturated; in this embodiment, after the sample battery pack reaches the upper limit voltage for the first time, two more processes of standing still and then charging with reduced current are performed, which not only ensures the voltage capacity of the sample battery pack, but also does not increase excessive test time.

[0069] Step S224: after the sample battery pack is left standing for time T4, perform constant current discharge on the sample battery pack with a current of magnitude I4 until the voltage of the sample battery pack reaches the lower limit voltage, so as to obtain the discharge capacity value, the discharge temperature value and the second discharge capacity difference of the sample battery pack.

[0070] Since the initial voltages of the individual cells in the sample battery pack are not completely the same, and the voltages after constant current charging are also not completely the same, when performing constant current discharge on the sample battery pack, as long as the voltage of one cell reaches the lower limit voltage, it is considered that the voltage of the sample battery pack reaches the lower limit voltage, and the discharge is stopped at this time.

[0071] In the embodiments of the present application, I3<I2<I1=I4, T1=T2=T3<T4. Optionally, I1=I4=1 / 3C, I2=0.2C, I3=0.1C; T1=T2=T3≥30s, T4≥30min, for example, T1=T2=T3=1min, T4=30min. Wherein, C is the nominal capacity, which refers to the minimum capacity that the sample battery pack should release under certain discharge conditions, for example, the capacity that the sample battery pack can output when discharging from the upper limit voltage to the lower limit voltage with a certain discharge current.

[0072] In practical applications, when performing charge and discharge tests on the sample battery pack, a battery management system (BMS: BATTERY MANAGEMENT SYSTEM) is used to detect the voltage and temperature of each cell in the sample battery pack in real time, and perform charge and discharge control based on this. Wherein, the discharge temperature value and the second discharge capacity difference of the sample battery pack are obtained from the battery management system, while the discharge capacity value is read from the discharge equipment.

[0073] The discharge temperature value refers to the temperature of the sample battery pack at the end of discharge. Wherein, since the sample battery pack includes multiple cells, the temperatures of the multiple cells at the end of discharge may be different. The temperature of the sample battery pack at the end of discharge may be an average value of the temperatures of the multiple cells at the end of discharge. In other possible implementation manners, the median, maximum value, minimum value, etc. of the temperatures of the multiple cells at the end of discharge may also be used as the discharge temperature value of the sample battery pack. The embodiments of the present application only take this as an example, and are not limited thereto.

[0074] The second discharge capacity difference can be the capacity difference between the upper limit voltage of the sample battery pack and the minimum discharge voltage, and the capacity difference between the upper limit voltage and the average discharge voltage. This application is not limited to this embodiment; in other possible implementations, it can also take other forms, such as the capacity difference between the upper limit voltage of the battery pack under test and the minimum discharge voltage, and the capacity difference between the upper limit voltage and the median discharge voltage. The second discharge capacity difference has the same form as the first discharge capacity difference.

[0075] The discharge capacity value refers to the capacity value output by the sample battery pack, such as the capacity read by the electrical equipment coupled to the discharge equipment from the start to the end of the discharge.

[0076] Additionally, after step S224, step S225 may be included: after the sample battery pack has been left to stand for a time T5, the consistency of all cells in the sample battery pack is determined by the voltage difference of their recovery. In this embodiment, T5 > 0; optionally, T5 ≥ 30 min, such as T5 = 30 min.

[0077] After the voltage of the sample battery pack reaches the lower limit voltage, the sample battery pack is left to stand for a period of time. The voltage of the sample battery pack will rebound. By observing the trend of voltage rebound after the sample battery pack is discharged, a simple judgment can be made on the consistency of the cells in the sample battery pack, so as to verify the conclusion of the cell consistency judgment in step S20. For example, if the voltage difference of the rebound of all cells in the sample battery pack is not greater than 100mV, the consistency of the cells in the sample battery pack is considered to be good. If the voltage difference of the rebound of the cells in the sample battery pack is greater than 100mV, the consistency of the cells in the sample battery pack is considered to be poor.

[0078] The specific testing steps are shown in the table below:

[0079] 1 Let stand 1 Deadline 2 Constant current charging 1 / 3C Upper limit voltage Voltage cutoff 3 Let stand 1 Deadline 4 Constant current charging 0.2C Upper limit voltage Voltage cutoff 5 Let stand 1 Deadline 6 Constant current charging 0.1C Upper limit voltage Voltage cutoff 7 Let stand 30 Deadline 8 Constant current discharge 1 / 3C Lower limit voltage Voltage cutoff 9 Let stand 30 Finish

[0080] In this embodiment, only the constant current charging of the battery pack after three resting cycles and then constant current discharging after resting is described as an example. In other possible implementations, the number of charging cycles, charging current, and discharging current of the battery pack can be adaptively adjusted. This embodiment is not limited to this.

[0081] Step S23: Based on the second discharge temperature rise value and the second discharge capacity difference of the sample battery pack, the second minimum capacity value is corrected to obtain the initial formula y'=x1'+x2'*k-x3', and thus the initial value of the capacity prediction of the sample battery pack is obtained, where y' is the initial value of the capacity prediction of the sample battery pack, x1' is the second minimum capacity value, x2' is the second discharge temperature rise value and x2'=discharge temperature value-initial temperature value, k is the temperature influence coefficient of the sample battery pack, and x3' is the second discharge capacity difference.

[0082] In this embodiment, the initial temperature value can be the ambient temperature value for the charge-discharge test. In this embodiment, the ambient temperature value for the charge-discharge test is 25℃±2℃. Alternatively, it can be obtained by averaging the initial temperatures of all cells in the sample battery pack. For example, before step S22, the method further includes: obtaining the temperature data of all cells in the sample battery pack and obtaining the average temperature from them. The temperature data of all cells can be directly obtained from the cell traceability system.

[0083] The temperature influence coefficient k is a known value, but it is important to know that for a battery cell, the temperature influence coefficient is not a constant value. Instead, its value changes as the discharge temperature rises to different temperature ranges. However, for the same temperature range, the temperature influence coefficient is a fixed value.

[0084] Taking a lithium iron phosphate battery cell as an example, it is subjected to constant current discharge at a current of 1 / 3C. At 25℃, the capacity of the lithium iron phosphate battery cell is 136.78Ah. When the discharge temperature rise is within 10℃ (including 10℃), for every degree increase in discharge temperature rise, the cell capacity increases by (139.75-136.78) / (35-25)=0.297Ah. When the discharge temperature rise is within 15℃ (including 15℃), for every degree increase in discharge temperature rise, the cell capacity increases by (139.47-136.78) / (4 0-25)=0.179Ah; When the discharge temperature rise is within 20℃ (including 20℃), for every degree increase in discharge temperature rise, the cell capacity increases by (139.14-136.78) / (45-25)=0.118Ah; It can be seen that when the discharge temperature rise is less than or equal to 10℃, k=0.297Ah / ℃; when the discharge temperature rise is greater than 10℃ and less than or equal to 15℃, k=0.179Ah / ℃; when the discharge temperature rise is greater than 15℃ and less than or equal to 20℃, k=0.118Ah / ℃. See the table below for details:

[0085]

[0086] Step S24: Repeat steps S21-S23 to obtain the discharge capacity value and initial capacity prediction value of several sample battery packs, and obtain the capacity compensation value by linear fitting the two.

[0087] Of course, if step S20 is also included, then step S24 is to repeat step S20-step S23.

[0088] In this embodiment, the capacity compensation value can be obtained by averaging the differences between the discharge capacity values ​​of several sample battery packs and the initial capacity prediction values. Alternatively, the capacity compensation value can be calculated by taking the median of the differences between the discharge capacity values ​​of several sample battery packs and the initial capacity prediction values, and by combining variance, standard deviation, etc. This embodiment is only an example and is not limited to this.

[0089] Step S25: Obtain the first discharge temperature rise value based on the second discharge temperature rise value of several sample battery packs, obtain the first discharge capacity difference value based on the second discharge capacity difference value of several sample battery packs, and compensate the initial formula based on the capacity compensation value to finally obtain the corrected formula y=x1+x2*k-x3+Δ.

[0090] Since x2' and x3' in the initial formula y'=x1'+x2'*k-x3' are both unknown values ​​related to the battery pack, in this embodiment, the first discharge temperature rise value x2 is obtained by taking the second discharge temperature rise value of several sample battery packs. For example, the value of x2 is obtained by taking the mean, median and variance of the second discharge temperature rise values ​​of several sample battery packs. The first discharge capacity difference value x3 is obtained by taking the mean, median and variance of the second discharge capacity difference of several sample battery packs. Thus, in the final corrected formula y=x1+x2*k-x3+Δ, the variable is only x1, thereby realizing the prediction of system capacity based on the cell capacity of the battery pack.

[0091] It should be noted that in this embodiment, the first discharge temperature rise value x2 is used as the discharge temperature rise of the battery pack under test to determine the k value of the battery pack under test. Taking the above embodiment as an example, when the battery cell is a lithium iron phosphate cell, when it is discharged with a constant current of 1 / 3C, k = 0.297Ah / ℃ when the discharge temperature rise is less than or equal to 10℃; k = 0.179Ah / ℃ when the discharge temperature rise is greater than 10℃ and less than or equal to 15℃; and k = 0.118Ah / ℃ when the discharge temperature rise is greater than 15℃ and less than or equal to 20℃. That is, if x2 ≤ 10℃, then k = 0.297Ah / ℃; if 10℃ < x2 ≤ 15℃, then k = 0.179Ah / ℃; and if 15℃ < x2 ≤ 20℃, then k = 0.118Ah / ℃.

[0092] In one possible implementation, to determine whether the capacity prediction value obtained in step S2 is reasonable, the battery pack system capacity prediction method provided in this application embodiment may further include, after step S2:

[0093] Step S3: Verify the predicted capacity of the battery pack under test based on the first minimum and first maximum capacity values. If the predicted capacity value of the battery pack under test is between the first minimum and first maximum capacity values ​​(i.e., first minimum capacity ≤ predicted capacity ≤ first maximum capacity), it indicates that the predicted capacity value is reasonable, and the verification passes. Conversely, if the predicted capacity value is not reasonable, the verification fails. Accordingly, step S1 requires obtaining not only the first minimum capacity value of the battery pack under test but also the first maximum capacity value.

[0094] Since a battery pack typically consists of several cells connected in series to achieve high voltage, its capacity is determined by the capacity of the cell that first reaches the discharge cutoff condition (i.e., the lower limit voltage). In other words, the battery pack capacity is equal to the minimum capacity of all cells. Considering the voltage difference effect during series discharge, the overall capacity released will be lower than the maximum capacity of all cells. Therefore, the minimum and maximum capacities are used to verify the predicted capacity.

[0095] Correspondingly, such as Figure 3 As shown, this embodiment also provides an electronic device, which includes a memory 100 and a processor 200; wherein the memory 100 is used to store a computer program, and the processor 200 is used to execute the computer program stored in the memory 100 to enable the electronic device to perform the battery pack system capacity prediction method described above.

[0096] Specifically, memory 100 may include, but is not limited to, high-speed random access memory, non-volatile memory, such as one or more disk storage devices, flash memory devices, or other non-volatile solid-state storage devices.

[0097] Specifically, the processor 200 can be a general-purpose processor, including one or more central processing units (CPUs), network processors (NPs), etc.; it can also be a microcontroller unit (MCU), digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0098] Accordingly, this embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the battery pack system capacity prediction method described above.

[0099] Specifically, computer-readable storage media may include, but are not limited to, floppy disks, optical disks, CD-ROMs (compact disc read-only memory), magneto-optical disks, ROMs (read-only memory), RAMs (random access memory), EPROMs (erasable programmable read-only memory), EEPROMs (electrically erasable programmable read-only memory), magnetic cards or optical cards, flash memory, or other types of media / machine-readable media suitable for storing machine-executable instructions. Furthermore, the computer-readable storage medium may be a product not connected to a computer device or a component used in a computer device.

[0100] In summary, the battery pack system capacity prediction method, electronic device, and storage medium of the present invention, based on a preset relationship between a first minimum capacity value, a first discharge temperature rise value, a first discharge capacity difference, and a predicted capacity value in the battery pack under test, corrects the first minimum capacity value using the first discharge temperature rise value and the first discharge capacity difference. This allows for prediction of the system capacity solely based on the minimum capacity of all cells in the battery pack, enabling rapid prediction of the system capacity from cell capacity in the manufactured battery pack, improving testing efficiency and reducing production costs. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0101] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for predicting the capacity of a battery pack system, characterized in that, The prediction method includes: S1 obtains the first minimum capacity of all cells in the battery pack under test; S2 determines the predicted capacity value of the battery pack under test based on a preset relationship between the first minimum capacity value and the first discharge temperature rise value, the first discharge capacity difference value, and the predicted capacity value of the battery pack under test; wherein, the first discharge temperature rise value is the difference between the discharge temperature and the initial temperature of the battery pack under test; the first discharge capacity difference value is the capacity difference between the capacity corresponding to the minimum value of the upper limit voltage to the discharge end voltage of the battery pack under test and the capacity corresponding to the average or median value of the upper limit voltage to the discharge end voltage. The preset relationship satisfies the correction formula y=x1+x2*k-x3+Δ, where y is the predicted capacity of the battery pack under test, x1 is the first minimum capacity, x2 is the first discharge temperature rise, k is the temperature influence coefficient of the battery pack under test, x3 is the first discharge capacity difference, and Δ is the capacity compensation value of the battery pack under test.

2. The method for predicting the capacity of a battery pack system according to claim 1, characterized in that, Before step S2, the following may also be included: S21 obtains the second minimum capacity of all cells in the sample battery pack; S22 performs charge and discharge tests on the sample battery pack to obtain the discharge capacity value, discharge temperature value, and second discharge capacity difference value. S23 corrects the second minimum capacity value based on the second discharge temperature rise value and the second discharge capacity difference of the sample battery pack, and obtains the initial formula y'=x1'+x2'*k-x3', and thus obtains the initial value of the capacity prediction of the sample battery pack, where y' is the initial value of the capacity prediction of the sample battery pack, x1' is the second minimum capacity value, x2' is the second discharge temperature rise value and x2'=discharge temperature value-initial temperature value, and x3' is the second discharge capacity difference; S24 repeats S21-S23 to obtain the discharge capacity value and initial capacity prediction value of several sample battery packs, and obtains the capacity compensation value by linear fitting the two. S25 obtains the first discharge temperature rise value based on the second discharge temperature rise value of several sample battery packs, obtains the first discharge capacity difference value based on the second discharge capacity difference value of several sample battery packs, and compensates the initial formula based on the capacity compensation value, finally obtaining the corrected formula y=x1+x2*k-x3+Δ.

3. The method for predicting the capacity of a battery pack system according to claim 2, characterized in that, The method for performing charge-discharge tests on the sample battery pack includes: S221 After the sample battery pack is left to stand for a time T1, it is charged with a constant current of I1 until the voltage of the sample battery pack reaches the upper limit voltage. S222 After the sample battery pack is left to stand for a time T2, it is charged with a constant current of I2 until the voltage of the sample battery pack reaches the upper limit voltage. S223 After the sample battery pack is left to stand for a time T3, it is charged with a constant current of I3 until the voltage of the sample battery pack reaches the upper limit voltage. S224 After the sample battery pack is left to stand for T4 time, it is discharged at a constant current of I4 until the voltage of the sample battery pack reaches the lower limit voltage, thereby obtaining the discharge capacity value, discharge temperature value and second discharge capacity difference value of the sample battery pack. Where I3 < I2 < I1 = I4, T1 = T2 = T3 <T4。 4. The method for predicting the capacity of a battery pack system according to claim 3, characterized in that, After step S224, the method further includes: S225 After the sample battery pack has been left to stand for a time T5, the consistency of all cells in the sample battery pack is determined by using the voltage difference of the recovery of all cells in the sample battery pack.

5. The method for predicting the capacity of a battery pack system according to claim 3 or 4, characterized in that, I1=I4=1 / 3C, I2=0.2C, I3=0.1C, where C is the nominal capacity; T1=T2=T3≥30s, T4≥30min, T5>0.

6. The method for predicting the capacity of a battery pack system according to any one of claims 1-4, characterized in that, Prior to step S1, the prediction method further includes: Based on the SOC of all cells in the battery pack under test, and the voltage difference and tolerance between any two cells, determine whether the cells in the battery pack under test meet the consistency requirements. Alternatively, based on the internal resistance, SOC, and voltage difference and tolerance between any two cells in the battery pack under test, it can be determined whether the cells in the battery pack under test meet the consistency requirements. If it is determined that the cells in the battery pack under test meet the consistency requirements, then step S1 is executed.

7. The method for predicting the capacity of a battery pack system according to any one of claims 1-4, characterized in that, S1 also includes the step of obtaining the first maximum capacity of all cells in the battery pack under test; At this point, the prediction method further includes: S3 verifies the predicted capacity of the battery pack under test based on the first minimum capacity and the first maximum capacity. If the predicted capacity of the battery pack under test is between the first minimum capacity and the first maximum capacity, the verification passes; otherwise, the verification fails.

8. An electronic device, characterized in that, The electronic device includes a memory and a processor, the memory storing a computer program and the processor executing the computer program stored in the memory to cause the electronic device to perform the battery pack system capacity prediction method as described in any one of claims 1-7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for predicting the capacity of a battery pack system as described in any one of claims 1-7.

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