Power battery system and SOC estimation method and system thereof

Abstract

The invention relates to a power battery system and an SOC estimation method and system thereof, and belongs to the technical field of battery management. According to the power battery system SOC estimation method based on the battery model, an SOC estimation algorithm combining ampere-hour integration with high-end and low-end correction and an SOC estimation algorithm adopting the battery model are combined, and the SOC of the power battery system is estimated by adopting the SOC estimation method based on the battery model; and if the condition that the parameter residual error is smaller than the set residual error threshold value, the battery is in a discharge state, the internal polarization internal resistance change is smaller than the set threshold value or the current fluctuation is larger than the set threshold value is not met, estimating the SOC of the power battery system by using a method of combining ampere-hour integration with high-low end correction. SOC estimation is carried out on a high end and a low end in an SOC estimation algorithm in which ampere-hour integration is combined with high-low end correction, and an obtained relation model is improved in an SOC estimation algorithm in which a battery model is adopted, so that SOC estimation of a vehicle under a complex and severe working condition is realized.

Description

Technical Field

[0001] The present invention relates to a power battery system and a SOC estimation method and system thereof, belonging to the technical field of battery management. Background Art

[0002] In recent years, new energy vehicles, mainly electric vehicles, have developed rapidly. The calculation of SOC (State of Charge) is one of the key technologies of BMS (Battery Management System) in new energy vehicles. As one of the important decision-making factors for energy management, SOC plays an important role in optimizing vehicle energy management, improving power battery capacity and energy utilization, preventing power battery overcharge and overdischarge, and ensuring the safety and long life of power batteries during use. At present, the mainstream algorithms for estimating SOC are the SOC estimation algorithm combining ampere-hour integration with high and low-end corrections, and the SOC estimation algorithm based on the battery model.

[0003] The SOC estimation algorithm that combines ampere-hour integration with high- and low-end correction mainly performs coulomb counting through current acquisition, calibrates the SOC at the low end by performing an OCV lookup table based on the voltage after 1H at the end of discharge, and performs 100% calibration at the high end based on the full charge voltage. However, this method is too dependent on the initial SOC accuracy, and as the current acquisition error accumulates, the SOC calculation deviation gradually increases. Although it has a certain SOC calibration capability, it must trigger high-end correction and low-end correction scenarios to achieve high- and low-end correction. For the SOC estimation algorithm based on the battery model, if the OCV-SOC relationship is used to calculate the model parameters in the lithium iron phosphate battery, it may lead to inaccurate convergence intervals in the middle section, and then lead to non-convergence of parameters and other results, and use the final calculated new information to correct the initial SOC value. If braking feedback occurs during driving, it will lead to inaccurate parameter identification and affect the accuracy of SOC correction. Summary of the invention

[0004] The purpose of the present invention is to provide a power battery system and its SOC estimation method and system, so as to solve the problems that when the ampere-hour integration combined with the high- and low-end correction SOC algorithm is used, the high- and low-end correction of the SOC cannot be realized when the high- and low-end correction scenes cannot be triggered, and when the battery model SOC estimation algorithm is used, the scale precision gap of the OCV and SOC relationship table is large, resulting in low SOC estimation accuracy, and the occurrence of brake feedback during driving leads to inaccurate parameter identification, affecting the SOC correction accuracy.

[0005] To achieve the above objectives, the technical solutions and corresponding solutions provided by the present invention have the following beneficial effects:

[0006] A method for estimating the SOC of a power battery system of the present invention, in the process of estimating the SOC of the power battery system by using the SOC estimation method based on a battery model, if any of the following conditions is not met, the SOC of the power battery system is estimated by using an ampere-hour integration combined with a high-end and low-end correction method: the parameter residual is continuously less than a set residual threshold value within a first required time period, the battery is in a discharge state, the change in polarization internal resistance within a second required time period is less than a set internal resistance change threshold value, and the current fluctuation is greater than a set current change threshold value.

[0007] The beneficial effect of the above technical solution is: combining the SOC estimation method based on the battery model with the method of combining ampere-hour integration with high and low end correction to estimate the SOC of the power battery system. In the process of estimating the SOC of the power battery system using the SOC estimation method based on the battery model, if the parameter residual is continuously less than the set residual threshold value during the first required time period, the battery is in a discharge state, the polarization internal resistance change is less than the set internal resistance change threshold value during the second required time period, and the current fluctuation is greater than the set current change threshold value, then the SOC of the power battery system is estimated by using the method of ampere-hour integration combined with high and low end correction to ensure the robustness of the model-based SOC estimation algorithm. Even if the model algorithm fails, an alternative algorithm is enabled, and the algorithm will not be disabled due to model non-convergence.

[0008] As a further improvement of the method, when the SOC estimation method based on the battery model is used to estimate the SOC of the power battery system, the relationship MAP between OCV and SOC is obtained by the following steps:

[0009] 1) Perform a battery discharge experiment to obtain the relationship MAP between CCV and SOC;

[0010] 2) After replacing the OCV-SOC relationship MAP in the battery model with the CCV-SOC relationship MAP, the corresponding SOC is calculated using the SOC estimation method based on the battery model, and the calculated SOC is recorded as a; wherein the SOC scale corresponding to the CCV-SOC relationship MAP is smaller than the SOC scale corresponding to the OCV-SOC relationship MAP;

[0011] 3) Calculate the SOC value corresponding to the battery under standard operating conditions, and record the calculated SOC as b;

[0012] 4) Calculate the deviation between a and b, compensate the CCV voltage in the relationship MAP between CCV and SOC based on the deviation, and then calculate a. When a is consistent with b, the obtained relationship MAP is recognized as the relationship MAP between OCV and SOC.

[0013] The beneficial effects of the above technical solution are as follows: when the model parameters are obtained by directly using the OCV and SOC relationship MAP in the traditional way, the scale of the OCV and SOC relationship table is at 5% SOC, which may cause inaccurate convergence interval in the middle section in some batteries, thereby causing the parameters not to converge. The present invention uses the more accurate CCV and SOC relationship MAP to correct the traditional OCV and SOC relationship MAP, obtain the OCV and SOC relationship MAP with a scale of 1%, and improve the accuracy of the final estimated SOC.

[0014] As a further improvement of the method: the parameter residual is continuously less than the set residual threshold within the first required time period, which means that the parameter residual is continuously less than 20mv within 180S; the polarization internal resistance change within the second required time period is less than the set internal resistance change threshold, which means that the polarization internal resistance change calculated by the battery model within 300 seconds is less than the change threshold of 0.01mΩ; the current fluctuation is greater than the set current change threshold, which means that the current fluctuation at adjacent moments is greater than 5A.

[0015] As a further improvement of the method, when the SOC estimation method based on the battery model is used to estimate the SOC of the power battery system, the following method is used to judge the charge and discharge state of the battery system: when the battery changes from a charging state to a discharging state and the discharge capacity is 2a%, or when the battery changes from a static state to a discharging state and the discharge capacity is a%, the battery is judged to be in a discharging state; when the battery changes from a discharging state to a charging state and the charge capacity is 2a%, or when the battery changes from a static state to a charging state and the charge capacity is a%, the battery is judged to be in a charging state, wherein a% is the change in capacity of the battery when charging or discharging.

[0016] The beneficial effects of the above technical solution are as follows: the present invention further limits the determination of the battery charging and discharging state, effectively avoiding the errors caused by the feedback condition during vehicle operation on parameter identification and SOC correction under the discharge condition, and improving the accuracy of SOC estimation.

[0017] As a further improvement of the method, when the power battery system is in a charging state, the single cell with the largest single cell capacity is used to calculate its SOC value, which is used as the SOC of the power battery system in the charging state; when the power battery system is in a discharging state, the single cell with the smallest single cell capacity is used to calculate its SOC, which is used as the SOC of the power battery system in the discharging state.

[0018] The beneficial effect of the above technical solution is: by calculating the capacity of all cells in the battery system, the maximum capacity cell and the minimum capacity cell are obtained, the SOC calculated from the maximum capacity cell is used as the SOC of the battery system in the charging state, and the SOC calculated from the minimum capacity cell is used as the SOC of the battery system in the discharging state, so as to estimate the SOC of the entire system in the charging and discharging state.

[0019] As a further improvement of the method, when the method of using ampere-hour integration combined with high-end and low-end correction to estimate the SOC of the power battery system, the low-end correction step includes:

[0020] A. Measure the temperature, current and voltage of the battery system. When the battery temperature is within the open temperature range and the current fluctuation and voltage are stable, obtain the battery DC internal resistance DCR.

[0021] B. Determine whether U+DCR*I is within the set low-end region, where U is the voltage value after voltage stabilization, and I is the current value when current fluctuation is stable; the maximum value of the low-end region value range is: the OCV value obtained by the relationship MAP between OCV and SOC, minus a certain offset;

[0022] C. When U+DCR*I satisfies the set low-end area, (U+DCR*I)+Uoffset is calculated as the OCV voltage value at the current moment, where Uoffset is the offset caused by polarization;

[0023] D. Using the calculated OCV voltage value, according to the relationship MAP between OCV and SOC, the SOC of the current power battery system is obtained.

[0024] The beneficial effect of the above technical solution is: when estimating the SOC of the power battery system by using the method of ampere-hour integration combined with high- and low-end correction, for the low-end correction, if the traditional method is used for correction, the low-end voltage needs to be left static for more than 1H to be triggered. The present invention calculates the OCV at the current moment, and calculates the SOC based on the relationship MAP between OCV and SOC, thereby realizing short-term correction of the vehicle on the low-end platform.

[0025] As a further improvement of the method, the method of using ampere-hour integration combined with high-end and low-end correction to estimate the SOC of the power battery system, wherein the high-end correction method includes the following steps:

[0026] a. When the current charging rate is less than a certain threshold and the charging temperature is within a certain range within a certain period of time before the current time, obtain the current charging temperature and terminal voltage;

[0027] b. Based on the obtained charging temperature, terminal voltage and charging rate data at the current moment, and combined with the constructed corresponding relationship between the charging temperature, terminal voltage and charging rate and SOC, the SOC corresponding to the current moment is obtained.

[0028] The beneficial effect of the above technical solution is: when the traditional method is used to correct the SOC of the battery system on the high-end platform, the vehicle needs to be fully charged and calibrated, and the high-end correction cannot be triggered for the under-charged state. The present invention obtains the charging temperature Temp2, terminal voltage and charging rate under specific conditions, and performs a table lookup in the constructed charging temperature, terminal voltage and charging rate relationship to achieve the high-end platform correction of the battery system under the under-charged state.

[0029] As a further improvement of the method, the constructed corresponding relationship between the charging temperature, terminal voltage, charging rate and SOC is stored in a table form.

[0030] The beneficial effect of the above technical solution is: the charging temperature, terminal voltage and charging rate relationship data are displayed in a table form, so as to simply and clearly obtain the SOC of the battery system when the high-end platform is corrected.

[0031] A SOC estimation system for a power battery system of the present invention comprises a memory and a processor, wherein the processor is used to execute computer program instructions stored in the memory to implement the SOC estimation method for the power battery system described above.

[0032] The beneficial effect of the above technical solution is as follows: the present invention combines the SOC estimation method based on the battery model with the method of estimating the SOC of the power battery system by combining ampere-hour integration with high and low-end correction to cover all vehicle operating conditions such as the low platform area, high platform area, and middle section, especially hybrid or quasi-hybrid conditions. Even if the vehicle is not fully charged and not stationary, the real SOC can be calculated relatively accurately to reduce the risk of vehicle breakdown.

[0033] A power battery system of the present invention includes the SOC estimation system of the power battery system described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a SOC estimation flow chart of the prior art combining time-based integration with high-end and low-end correction;

[0035] Figure 2 The short-term correction process of the low-end platform of the present invention is shown in the figure;

[0036] Figure 3 It is a flow chart of the correction of the charging terminal of the high-end platform of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0038] The purpose of the present invention is to provide a power battery system, a SOC estimation method for a power battery system, and a SOC estimation system for a power battery system. By integrating and improving the SOC estimation algorithm of the ampere-hour integration combined with the high-end and low-end corrections and the SOC estimation algorithm of the battery model, the real SOC of the vehicle can be calculated even if it is not fully charged or stationary under the low-end platform and the high-end platform, and the scale of the OCV and SOC relationship MAP is finely divided, and the judgment of the battery charging and discharging state is improved, avoiding the error caused by the feedback working condition of the vehicle running on the parameter identification and SOC correction under the discharge working condition, and improving the accuracy of SOC estimation.

[0039] An embodiment of a method for estimating SOC of a power battery system:

[0040] The method for estimating the SOC of the power battery system in this embodiment is:

[0041] like Figure 1 As shown, the steps of estimating the SOC of the power battery system using the SOC estimation method based on the battery model are as follows:

[0042] ① Based on the SOC value at the previous moment or the initial SOC and the current measurement value, the current SOC estimate is calculated using the ampere-hour integration.

[0043] ② Calculate the model parameter value at this time based on the model parameter-SOC relationship, such as the relationship MAP between OCV and SOC.

[0044] Specifically, the steps for calculating the model parameter values ​​are:

[0045] 1) Perform a battery discharge experiment to obtain the relationship MAP between CCV and SOC;

[0046] 2) After replacing the OCV-SOC relationship MAP in the battery model with the CCV-SOC relationship MAP, the corresponding SOC is calculated using the SOC estimation method based on the battery model, and the calculated SOC is recorded as a; wherein the SOC scale corresponding to the CCV-SOC relationship MAP is smaller than the SOC scale corresponding to the OCV-SOC relationship MAP;

[0047] 3) Calculate the SOC value corresponding to the battery under standard operating conditions, and record the calculated SOC as b;

[0048] 4) Calculate the deviation between a and b, compensate the CCV voltage in the relationship MAP between CCV and SOC based on the deviation, and then calculate a. When a is consistent with b, the obtained relationship MAP is recognized as the relationship MAP between OCV and SOC.

[0049] ③ Calculate the model terminal voltage at this time based on the model terminal voltage-parameter relationship.

[0050] ④ Based on the voltage measurement value, obtain the model terminal voltage error, that is, new information, referred to as new information.

[0051] Specifically, when calculating the model terminal voltage of the battery pack, the vehicle is stationary on the high platform, the middle section, and the low platform, and the voltage of all cells is recorded in real time. Then, the actual maximum capacity cell and minimum capacity cell are screened out for comparison under different platforms. When the battery pack system is in the charging state, the cell with the largest cell capacity is selected to calculate the SOC, and the calculated SOC is used as the SOC of the power battery system in the charging state; when the power battery system is in the discharging state, the cell with the smallest cell capacity is selected to calculate the SOC, and the calculated SOC is used as the SOC of the power battery system in the discharging state.

[0052] ⑤ Correct the above SOC estimate with a certain gain of the new information to obtain the final SOC correction value, and use it as input at the next moment.

[0053] Specifically, when using the new information to correct the SOC estimate, the way to judge the charging and discharging state of the battery system is: when the battery changes from the charging state to the discharging state and the discharge capacity is 2a%, or the battery changes from the static state to the discharging state and the discharge capacity is a%, the battery is judged to be in the discharging state; when the battery changes from the discharging state to the charging state and the charging capacity is 2a%, or the battery changes from the static state to the charging state and the charging capacity is a%, the battery is judged to be in the charging state, where a% is the change in capacity when the battery is charged or discharged. (For example: the charging state is 1, the discharging state is -1, and the change in charging or discharging capacity is set to 5%, then it takes 10% to discharge from the fully charged state to the fully discharged state, and 5% to discharge from the 0 state to the discharged state)

[0054] When using the new information to correct the SOC estimate, the middle section and the low end are selected according to the characteristics of the OCV curve. Within the convergence interval, if any of the following conditions is not met, the SOC of the power battery system is estimated using the ampere-hour integration combined with the high- and low-end correction method: the parameter residual is continuously less than the set residual threshold within the first required time period, the battery is in a discharge state, the change in polarization internal resistance within the second required time period is less than the set internal resistance change threshold, and the current fluctuation is greater than the set current change threshold.

[0055] Specifically, Figure 2 and Figure 3As shown, the process of estimating the SOC of the power battery system by using the method of ampere-hour integration combined with high- and low-end correction is as follows: coulomb counting is performed through current acquisition, and the SOC is calibrated by OCV table lookup at the low end, and the current charging temperature, terminal voltage, and charging rate data are calculated at the high end, and based on the calculated data, a query is performed in the relationship table established using the charging temperature, terminal voltage, and charging rate data to obtain the corresponding SOC.

[0056] Specifically, Figure 2 As shown, the short-term correction of the low-end platform includes the following steps:

[0057] (1) The temperature Temp should be within the temperature range where the algorithm can be enabled.

[0058] (2) The battery discharge current is continuously determined until the current I fluctuates less than a certain value I1 within a certain period of time T1.

[0059] (3) Determine whether the battery terminal voltage U changes less than a certain specific value U1 within the above time.

[0060] (4) According to the current temperature, the current DC internal resistance DCR (Direct Current Resistance) is obtained.

[0061] (5) Determine whether (U+DCR*I) is within the table-lookup range. The maximum range of the table-lookup range is determined based on the actual cell OCV-SOC map. For example, the table-lookup range of a certain lithium iron phosphate cell is the OCV voltage corresponding to 25% SOC minus a 10mv offset (the offset here can be set according to actual needs or can be set to 0), that is, (OCV25%SOC-10mv).

[0062] (6) Calculate the current OCV voltage, that is, OCV = (U + DCR * I) + Uoffset, where Uoffset is the offset caused by polarization, which is related to the change in the terminal voltage in step ③ within time T1.

[0063] (7) Using the OCV-SOC relationship table, calculate the SOC of the current battery system according to the OCV in step ⑥.

[0064] Among them, the DCR value of a certain battery cell is shown in Table 1 below:

[0065] Table 1

[0066] temperature coefficient DCR 25℃ 1 0.75 10℃ 1.5 1.125 0℃ 2 1.5 -10℃ 3.3 2.475 -20℃ 5 3.75

[0067] Among them, because DCR is proportional to battery aging, a coefficient K needs to be added, which is closely related to SOH.

[0068] like Figure 3 As shown, the steps for correcting the charging terminal in the high platform area are as follows:

[0069] (1) During charging, the current charging rate and charging temperature are calculated in real time.

[0070] (2) The charging rate change is less than a certain threshold value I2.

[0071] (3) Obtain the temperature Temp2, terminal voltage U2 and charging rate K2 when the above conditions are met, and the temperature Temp1 half an hour before the conditions are met should be within a certain range.

[0072] (4) Obtain the corresponding SOC according to the charging temperature Temp2, the terminal voltage U2 and the charging rate K2.

[0073] Among them, when the terminal voltage of a certain battery cell is 3.5V, the corresponding charging temperature, terminal voltage and charging rate relationship are shown in Table 2 below:

[0074] Table 2

[0075] Ratio\Temperature 25℃ 45℃ 0.33C 98.5％ 99.4％ 0.5C 97.5％ 99％ 1C 92.5％ 97％

[0076] An embodiment of a SOC estimation system for a power battery system:

[0077] A power battery SOC estimation system includes a memory and a processor, and data is exchanged between the memory and the processor via an internal bus. The processor is used to execute computer program instructions stored in the memory to implement a SOC estimation method for a power battery system of the present invention. The specific content of the method has been described in detail in the embodiment of the power battery SOC estimation method, and will not be repeated in this embodiment. Among them, the memory can be selected from semiconductor memory, magnetic surface memory, read-only memory, sequential memory, etc., and the processor can be selected from Intel processor, MD processor, IBM processor, MediaTek processor, etc.

[0078] A power battery system embodiment:

[0079] A power battery system includes a plurality of power battery cells. The SOC estimation of the power battery system is implemented by using a SOC estimation method introduced in a SOC estimation system of a power battery system. The specific content of the SOC estimation method has been introduced in detail in the SOC estimation system of the power battery system, and will not be repeated in this embodiment.

[0080] The present invention integrates the SOC estimation of ampere-hour integration combined with high- and low-end corrections and the SOC estimation algorithm scheme based on the battery model, improves the high-end charging terminal correction and the low-end platform short-time correction in the SOC estimation of ampere-hour integration combined with high- and low-end corrections, improves the calculation model parameters in the SOC estimation algorithm based on the battery model and the use of new information to correct the SOC estimated value, so as to obtain a more accurate SOC value for the vehicle. At the same time, when the vehicle is not fully charged and not stationary, its true SOC can also be calculated to reduce the risk of vehicle breakdown.

Claims

1. A method for estimating the SOC of a power battery system, characterized in that: In the process of estimating the SOC of the power battery system using the SOC estimation method based on the battery model, if any of the following conditions is not met, the SOC of the power battery system is estimated by using the method of ampere-hour integration combined with high-end and low-end correction: the parameter residual is continuously less than the set residual threshold within the first required time period, the battery is in a discharging state, the change in polarization internal resistance within the second required time period is less than the set internal resistance change threshold, and the current fluctuation is greater than the set current change threshold.

2. The SOC estimation method of the power battery system according to claim 1, characterized in that: When the SOC estimation method based on the battery model is used to estimate the SOC of the power battery system, the relationship MAP between OCV and SOC is obtained by the following steps: 1) Perform a battery discharge experiment to obtain the relationship MAP between CCV and SOC; 2) After replacing the OCV-SOC relationship MAP in the battery model with the CCV-SOC relationship MAP, the corresponding SOC is calculated using the SOC estimation method based on the battery model, and the calculated SOC is recorded as a; Among them, the SOC scale corresponding to the CCV and SOC relationship MAP is smaller than the SOC scale corresponding to the OCV and SOC relationship MAP; 3) Calculate the SOC value corresponding to the battery under standard operating conditions, and record the calculated SOC as b; 4) Calculate the deviation between a and b, compensate the CCV voltage in the relationship MAP between CCV and SOC based on the deviation, and then calculate a. When a is consistent with b, the obtained relationship MAP is recognized as the relationship MAP between OCV and SOC.

3. The SOC estimation method of the power battery system according to claim 1, characterized in that: The parameter residual is continuously less than the set residual threshold within the first required time period, which means that the parameter residual is continuously less than 20mv within 180S; the polarization internal resistance change within the second required time period is less than the set internal resistance change threshold, which means that the polarization internal resistance change calculated by the battery model within 300 seconds is less than the change threshold of 0.01mΩ; the current fluctuation is greater than the set current change threshold, which means that the current fluctuation at adjacent moments is greater than 5A.

4. The SOC estimation method of the power battery system according to claim 1, characterized in that: When the SOC estimation method based on the battery model is used to estimate the SOC of the power battery system, the charge and discharge state of the battery system is judged in the following manner: when the battery changes from a charging state to a discharging state and the discharge capacity is 2a%, or when the battery changes from a static state to a discharging state and the discharge capacity is a%, the battery is judged to be in a discharging state; when the battery changes from a discharging state to a charging state and the charge capacity is 2a%, or when the battery changes from a static state to a charging state and the charge capacity is a%, the battery is judged to be in a charging state, where a% is the change in capacity of the battery when charging or discharging.

5. The SOC estimation method of the power battery system according to claim 1, characterized in that: When the power battery system is in a charging state, the SOC value of the single cell with the largest single cell capacity is calculated as the SOC of the power battery system in the charging state; when the power battery system is in a discharging state, the SOC of the single cell with the smallest single cell capacity is calculated as the SOC of the power battery system in the discharging state.

6. The SOC estimation method of a power battery system according to any one of claims 1 to 5, characterized in that: When the method of using ampere-hour integration combined with high-end and low-end correction to estimate the SOC of the power battery system is used, the low-end correction step includes: A. Measure the temperature, current and voltage of the battery system. When the battery temperature is within the open temperature range and the current fluctuation and voltage are stable, obtain the battery DC internal resistance DCR. B. Determine whether U+DCR*I is within the set low-end region, where U is the voltage value after voltage stabilization, and I is the current value when current fluctuation is stable; the maximum value of the low-end region value range is: the OCV value obtained by the relationship MAP between OCV and SOC, minus a certain offset; C. When U+DCR*I satisfies the set low-end area, (U+DCR*I)+Uoffset is calculated as the OCV voltage value at the current moment, where Uoffset is the offset caused by polarization; D. Using the calculated OCV voltage value, according to the relationship MAP between OCV and SOC, the SOC of the current power battery system is obtained.

7. The SOC estimation method of a power battery system according to any one of claims 1 to 5, characterized in that: The method of estimating the SOC of the power battery system by using ampere-hour integration combined with high-end and low-end correction includes the following steps: a. When the current charging rate is less than a certain threshold and the charging temperature is within a certain range within a certain period of time before the current time, obtain the current charging temperature and terminal voltage; b. Based on the obtained charging temperature, terminal voltage and charging rate data at the current moment, and combined with the constructed corresponding relationship between the charging temperature, terminal voltage and charging rate and SOC, the SOC corresponding to the current moment is obtained.

8. The SOC estimation method of the power battery system according to claim 7, characterized in that: The constructed corresponding relationship between the charging temperature, terminal voltage, charging rate and SOC is stored in a table format.

9. A SOC estimation system for a power battery system, characterized in that: The method comprises a memory and a processor, wherein the processor is used to execute computer program instructions stored in the memory to implement the SOC estimation method of the power battery system according to any one of claims 1 to 7.

10. A power battery system, characterized in that: A SOC estimation system for a power battery system comprising the system as claimed in claim 9.

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