A method and device for calculating SOC of a power battery and an electric vehicle

Abstract

The present invention relates to a method, device and electric vehicle for calculating the SOC of a power battery. The method comprises the following steps: S01: judging whether the stationary time after the BMS sleeps is greater than a threshold value T1, if so, the initial real SOC is equal to the OCV table SOC value; if not, the initial real SOC is equal to the stored real SOC value; S02: performing continuous ampere-hour integral calculation based on the initial real SOC; S03: continuously judging whether the power battery is in a charging state, if so, judging whether the charging process correction condition is met, if so, updating the initial real SOC to the SOC charging process absolute correction value, clearing the ampere-hour integral value, and re-executing S02; if not, judging whether the discharge process correction condition is met, if so, updating the initial real SOC to the SOC discharge process absolute correction value, clearing the ampere-hour integral value, and re-executing S02. The present invention can correctly estimate the SOC, make the displayed SOC infinitely close to the real SOC, and prevent jumps during the SOC correction process.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery management systems, and in particular to SOC calculation technology of power batteries and electric vehicles. Background Art

[0002] The power battery components are the energy source for the operation of new energy vehicles, and the battery management system is one of the core components of the power battery. It manages and controls the battery system charging and discharging, SOC, SOH, SOP and other systems. SOC is one of the extremely important parameters, which characterizes the remaining charge of the power battery and is directly related to the calculation of the vehicle's cruising range. It is directly related to the user experience. Because the operating environment, working conditions and electrochemical characteristics of new energy vehicles are relatively complex, and there is no corresponding measurement quantity that can directly produce a relatively stable and accurate relationship with SOC, it brings great difficulties to the accurate estimation of SOC. Improving the accuracy of SOC estimation has become one of the topics that many manufacturers have to overcome.

[0003] At present, manufacturers mainly use ampere-hour integral calculation, supplemented by static OCV correction (open circuit voltage correction), voltage-based charge and discharge end correction and other correction methods to estimate SOC. The main problems are as follows: First, the OCV correction conditions are relatively harsh, and the power battery pack must be stationary for a period of time before it can be entered; second, due to the existence of current sensor acquisition errors, long-term ampere-hour integration has a large cumulative error, especially under long-term shallow charge and discharge conditions; third, after the battery power decays, the estimated SOC deviates greatly from the actual SOC; fourth, there are jumps in the SOC correction process. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for calculating the SOC of a power battery and an electric vehicle, and to solve the following technical problems:

[0005] First, long-term accumulation of ampere-hour points leads to inaccurate SOC estimation;

[0006] Second, there are jumps in the SOC correction process.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for calculating the SOC of a power battery, comprising the following steps:

[0008] S01: Determine whether the stationary time after the BMS sleep is greater than the threshold T1. If so, the initial real SOC is equal to the OCV table SOC value; if not, the initial real SOC is equal to the stored real SOC value;

[0009] S02: performing continuous ampere-hour integral calculation based on the initial real SOC;

[0010] S03: continuously determining whether the power battery is in a charging state; if so, determining whether the charging process correction condition is met; if so, updating the initial real SOC to the SOC discharge process absolute correction value, clearing the ampere-hour integral value, and re-executing S02; if not, determining whether the discharge process correction condition is met; if so, updating the initial real SOC to the SOC discharge process absolute correction value, clearing the ampere-hour integral value, and re-executing S02;

[0011] S04: If the discharge process correction condition or the charging process correction condition is not met, it is determined whether the minimum cell voltage is less than the voltage reference value at the corresponding temperature point. If so, the discharge end SOC self-learning is started;

[0012] S05: Determine whether the highest cell voltage is greater than the voltage reference value at the corresponding temperature point. If so, enter the charging terminal SOC self-learning;

[0013] S06: Output the real SOC and store it in the corresponding NVM;

[0014] S07: Determine whether the stationary time after the BMS sleeps is greater than the threshold value T2 and whether the static OCV table SOC is less than P1 (P1 is 10%), and whether the result obtained by subtracting the static OCV table SOC from the stored display SOC is greater than P2 (P2 is 5%);

[0015] S08: If the judgment result of S07 is true, the initial display SOC is equal to the OCV table SOC value; if the judgment result of S07 is false, the initial display SOC is equal to the stored display SOC value;

[0016] S09: performing continuous ampere-hour integral calculation with correction value k based on the initial display SOC;

[0017] S10: Determine whether the minimum cell voltage is less than the corresponding temperature point voltage reference value. If so, enter the discharge terminal SOC self-learning; if not, determine whether the maximum cell voltage is greater than the corresponding temperature point voltage reference value. If so, enter the charging terminal SOC self-learning; if not, execute S11;

[0018] S11: Output display SOC and store it in the corresponding NVM;

[0019] S12: Determine whether it is in a non-charging state and whether the deviation between the actual SOC and the displayed SOC is greater than P3 (P3 is 0.001);

[0020] S13: determining whether to enter into a discharge OCV acceleration correction or a discharge OCV deceleration correction according to the deviation between the displayed SOC and the actual SOC; when the deviation is greater than zero, entering into an acceleration correction; when the deviation is less than zero, entering into a deceleration correction;

[0021] S14: Determine whether it is in the charging state. If so, enter the charging OCV correction state. When the deviation is greater than zero, enter the charging deceleration correction state; when the deviation is less than zero, enter the SOC charging acceleration correction state.

[0022] S15: Determine whether it is in a non-charging state, if so, re-enter S13;

[0023] S16: Determine whether the remaining correction amount is less than P5 (P5 is 0.001) or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If yes, the correction rate is equal to 1;

[0024] S17: Determine whether the displayed SOC is greater than the absolute correction point of the discharge process and whether the minimum voltage of the single cell is less than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether it is in a non-charging state. If the judgment result is false, enter the waiting state for the discharge process correction condition to be met, and the correction rate is equal to 1;

[0025] S18: If the waiting time of S17 is greater than the threshold value T3, the discharge process is started and the SOC is accelerated and corrected, and the correction rate k is greater than 1;

[0026] S19: Determine whether it is in charging state, if yes, enter the charging process deceleration correction, and the correction rate is less than 1;

[0027] S20: Determine whether it is in a non-charging state, if so, enter the discharge process and perform SOC acceleration correction;

[0028] S21: Determine whether the remaining correction amount is less than P6 (P6 is 0.001) or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If the judgment result is true, the correction rate is equal to 1;

[0029] S22: Determine whether the displayed SOC is less than the SOC at the absolute correction point of the charging process and whether the maximum voltage of the single cell is greater than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether the charging rate meets the conditions and is in the charging state;

[0030] S23: If the judgment result of S22 is true, wait for the charging process correction condition to be met, and the correction rate k is equal to 1;

[0031] S24: If the judgment result of S22 is false, the correction rate is equal to 1, and the state is entered into an uncorrected state;

[0032] S25: If the waiting time in S23 is greater than the threshold value T3, then the charging process SOC is accelerated and the correction rate k is greater than 1;

[0033] S26: If the state is not charging, then the SOC deceleration correction during the discharge process is performed, and the correction rate k is less than 1;

[0034] S27: If the remaining correction amount is less than P4 (P4 is 0.001) or the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered, the correction rate k is equal to 1.

[0035] Preferably,

[0036] In the S02, the ampere-hour integral calculation is performed according to the following formula:

[0037] Among them, SOCReal t is the current real SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery.

[0038] Preferably,

[0039] In S09, the ampere-hour integral is calculated according to the following formula:

[0040]

[0041] Among them, SOCDisplay t is the current displayed SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery, k is the SOC correction rate, where, if k is equal to 1, there is no correction for the ampere-hour integral; if k is greater than 1, charging is corrected for deceleration and discharging is corrected for acceleration; if k is less than 1, charging is corrected for acceleration and discharging is corrected for deceleration.

[0042] Preferably,

[0043] In S03, if the charging process correction condition is met, the discharge process SOC acceleration correction in S18 is performed, and the correction rate k is greater than 1;

[0044] In S03, if the charging process correction condition is met, the charging process SOC acceleration correction in S25 is performed, and the correction rate k is greater than 1;

[0045] Preferably,

[0046] In S04, the voltage reference value at the corresponding temperature point is obtained by linearly interpolating the temperature, discharge rate and the single cell voltage MAP corresponding to the low SOC point, wherein the SOC is 3%, and the single cell voltage corresponding to the SOC of 3% is discharged at a rate of 0.1C, 0.2C, and 0.33C at each temperature point, forming the linear interpolation MAP of the voltage reference value at the corresponding temperature point.

[0047] Preferably,

[0048] In S05, the voltage reference value at the corresponding temperature point is obtained by linearly interpolating the temperature, the charging rate and the single cell voltage MAP corresponding to the high SOC point, wherein the SOC is 97%, and the single cell voltage corresponding to the SOC of 97% is charged at a rate of 0.1c, 0.2c, 0.33c, 0.5c, 0.8c, and 1c at each temperature point, forming the linear interpolation MAP of the voltage reference value at the corresponding temperature point.

[0049] Preferably,

[0050] In said S04, if no, then directly execute S05;

[0051] In S05, if no, then S06 is directly executed.

[0052] Preferably,

[0053] In the step S03, it is determined whether the charging process correction condition is met, and if so, the initial real SOC is updated to 90%; it is determined whether the discharging process correction condition is met, and if so, the initial real SOC is updated to 30%;

[0054] In said S01, the threshold T1 is 2h;

[0055] In said S07, the threshold T2 is 2h;

[0056] In the above S18, the threshold T3 is 10s.

[0057] The present invention also provides a SOC calculation device for a power battery, comprising:

[0058] The first judgment module is used to judge whether the static time after the BMS sleeps is greater than the threshold value T1. If so, the initial real SOC is equal to the OCV table SOC value; if not, the initial real SOC is equal to the stored real SOC value;

[0059] A first calculation module, configured to perform continuous ampere-hour integral calculation based on the initial real SOC;

[0060] a second judgment module, for continuously judging whether the power battery is in a charging state; if so, judging whether a charging process correction condition is satisfied; if so, updating the initial real SOC to an absolute correction value of the SOC discharge process, clearing the ampere-hour integral value, and re-executing the first calculation module; if not, judging whether a discharge process correction condition is satisfied; if so, updating the initial real SOC to an absolute correction value of the SOC discharge process, clearing the ampere-hour integral value, and re-executing the second judgment module;

[0061] The third judgment module is used to judge whether the minimum cell voltage is less than the voltage reference value of the corresponding temperature point if the discharge process correction condition or the charging process correction condition is not met, and if so, enter the discharge end SOC self-learning;

[0062] The fourth judgment module is used to judge whether the highest single cell voltage is greater than the voltage reference value of the corresponding temperature point. If so, the charging terminal SOC self-learning is started;

[0063] A first output module, used for outputting the real SOC and storing it in the corresponding NVM;

[0064] The fifth judgment module is used to judge whether the static time after the BMS sleeps is greater than the threshold value T2 and whether the static OCV table SOC is less than P1 (P1 is 10%) and whether the result obtained by subtracting the static OCV table SOC from the stored display SOC is greater than P2 (P2 is 5%); if the judgment result of S07 is true, the initial display SOC is equal to the OCV table SOC value; if the judgment result of S07 is false, the initial display SOC is equal to the stored display SOC value;

[0065] A second calculation module, configured to perform continuous ampere-hour integral calculation with a correction value k based on the initial displayed SOC;

[0066] The seventh judgment module is used to judge whether the minimum cell voltage is less than the corresponding temperature point voltage reference value. If so, the discharge terminal SOC self-learning is started; if not, the maximum cell voltage is judged to be greater than the corresponding temperature point voltage reference value. If so, the charging terminal SOC self-learning is started; if not, the second output module is executed;

[0067] The second output module is used to output the display SOC and store it in the corresponding NVM;

[0068] The eighth judgment module is used to judge whether it is in a non-charging state and whether the deviation between the real SOC and the displayed SOC is greater than P3 (P3 is 0.001); according to the deviation between the displayed SOC and the real SOC, determine whether to enter the discharge OCV acceleration correction or the discharge OCV deceleration correction; when the deviation is greater than zero, enter the acceleration correction; when the deviation is less than zero, enter the deceleration correction;

[0069] The ninth judgment module is used to judge whether it is in the charging state. If so, it enters the charging OCV correction state. When the deviation is greater than zero, it enters the charging deceleration correction; when the deviation is less than zero, it enters the SOC charging acceleration correction;

[0070] A tenth judging module, used for judging whether the battery is in a non-charging state, and if so, re-entering the eighth judging module;

[0071] The eleventh judgment module is used to judge whether the remaining correction amount is less than P5 (P5 is 0.001) or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If yes, the correction rate is equal to 1;

[0072] The twelfth judgment module is used to judge whether the displayed SOC is greater than the absolute correction point of the discharge process and whether the minimum voltage of the single cell is less than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether it is in a non-charging state. If the judgment result is false, the process enters the waiting state for the discharge process correction condition to be met, and the correction rate is equal to 1;

[0073] A thirteenth judgment module, configured to enter the discharge process SOC acceleration correction if the waiting time of the twelfth judgment module is greater than a threshold value T3, and the correction rate k is greater than 1;

[0074] A fourteenth judgment module is used to judge whether it is in a charging state. If so, the charging process is decelerated and corrected, and the correction rate is less than 1;

[0075] A fifteenth judgment module is used to judge whether it is in a non-charging state, and if so, enter the discharge process SOC acceleration correction;

[0076] A sixteenth judgment module is used to judge whether the remaining correction amount is less than P6 (P6 is 0.001) or whether to enter the charging terminal SOC self-learning state or whether to enter the discharging terminal SOC self-learning state. If the judgment result is true, the correction rate is equal to 1;

[0077] The seventeenth judgment module is used to judge whether the displayed SOC is less than the absolute correction point SOC of the charging process and whether the maximum voltage of the single cell is greater than or equal to the single cell voltage value corresponding to the correction point in the table under each temperature discharge rate and whether the charging rate meets the conditions and whether it is in the charging state; if the judgment result of S22 is true, wait for the charging process correction condition to be met, and the correction rate k is equal to 1; if the judgment result of S22 is false, the correction rate is equal to 1, and enters the uncorrected state;

[0078] An eighteenth judgment module, configured to perform an accelerated correction of the SOC during the charging process if the waiting time in the seventeenth judgment module is greater than a threshold value T3, and a correction rate k is greater than 1;

[0079] The nineteenth judgment module, if the state is not charging, performs SOC deceleration correction during the discharge process, and the correction rate k is less than 1;

[0080] The twentieth judgment module is used to determine that if the remaining correction amount is less than P4 (P4 is 0.001) or the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered, the correction rate k is equal to 1.

[0081] Preferably,

[0082] In the first calculation module, the ampere-hour integral calculation is performed according to the following formula:

[0083]

[0084] Among them, SOCReal t is the current real SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery.

[0085] Preferably,

[0086] In the second calculation module, the ampere-hour integral calculation is performed according to the following formula:

[0087]

[0088] Among them, SOCDisplay t is the current displayed SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery, k is the SOC correction rate, where, if k is equal to 1, there is no correction for the ampere-hour integral; if k is greater than 1, charging is corrected for deceleration and discharging is corrected for acceleration; if k is less than 1, charging is corrected for acceleration and discharging is corrected for deceleration.

[0089] Preferably,

[0090] In the second judgment module, if the charging process correction condition is met, the discharge process SOC acceleration correction in S18 is performed, and the correction rate k is greater than 1;

[0091] In S03, if the charging process correction condition is met, the charging process SOC acceleration correction in S25 is performed, and the correction rate k is greater than 1.

[0092] Preferably,

[0093] In the third judgment module, the voltage reference value of the corresponding temperature point is obtained by linearly interpolating the temperature, the discharge rate and the single cell voltage MAP corresponding to the low SOC point, wherein the SOC is 3%, and the single cell voltage corresponding to the SOC of 3% at each temperature point at a discharge rate of 0.1C, 0.2C, and 0.33C constitutes the linear interpolation MAP of the voltage reference value of the corresponding temperature point.

[0094] Preferably,

[0095] In the fourth judgment module, the voltage reference value of the corresponding temperature point is obtained by linearly interpolating the temperature, the charging rate and the single cell voltage MAP corresponding to the high SOC point, wherein the SOC is 97%, and each temperature point is charged at a rate of 0.1c, 0.2c, 0.33c, 0.5c, 0.8c, and 1c, corresponding to the single cell voltage of 97% SOC, forming the linear interpolation MAP of the voltage reference value of the corresponding temperature point.

[0096] Preferably,

[0097] In the third judgment module, if no, directly execute the fourth judgment module;

[0098] In the fourth judgment module, if not, the fifth judgment module is directly executed.

[0099] Preferably,

[0100] In the second judgment module, it is judged whether the charging process correction condition is met, and if so, the initial real SOC is updated to 90%; it is judged whether the discharging process correction condition is met, and if so, the initial real SOC is updated to 30%.

[0101] In the first judgment module, the threshold T1 is 2h;

[0102] In the fifth judgment module, the threshold T2 is 2h;

[0103] In the thirteenth judgment module, the threshold T3 is 10s.

[0104] The present invention also provides an electric vehicle, comprising the SOC calculation device of the power battery as described above.

[0105] By adopting the above technical solution, the present invention can achieve the following beneficial effects:

[0106] First, when the BMS is powered on, it enters OCV static correction depending on the conditions; at the end of charging and discharging, the voltage-based SOC terminal self-learning correction method is used; in the middle SOC segment of charging and discharging, multi-condition SOC discharge process absolute correction points and multi-condition SOC charging process absolute correction points are set; the combination of the above SOC correction strategies can effectively solve the problem of inaccurate SOC estimation caused by long-term ampere-hour integral accumulation error.

[0107] Second, using the normalization method, the BMS selects different correction rates k based on the SOC correction status and the deviation between the displayed SOC and the actual SOC. It smoothly adjusts the displayed SOC while quickly approaching the actual SOC to solve the jump problem in the SOC correction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0108] Figure 1 This is the actual SOC calculation flow chart;

[0109] Figure 2 To show the SOC calculation flow chart;

[0110] Figure 3 Revised state management flow chart for SOC. DETAILED DESCRIPTION

[0111] The present invention will be further described below in conjunction with the accompanying drawings.

[0112] The SOC calculation method of a power battery described in the present invention is generally divided into three major modules, including real SOC calculation, displayed SOC calculation and SOC correction state management.

[0113] Real SOC calculation module: used to characterize the current remaining real power of the power battery. The deviation of the remaining displayed SOC is used as one of the conditions for selecting the displayed SOC correction rate k. Once the value meets the correction condition, it will directly jump to the SOC correction target value.

[0114] Display SOC calculation module: used for the instrument to display the current remaining power of the power battery and the VCU (vehicle control unit) to calculate the remaining cruising range. The value changes smoothly during charging and discharging without correction mutations.

[0115] SOC correction status management: Based on the real SOC, displayed SOC, single cell voltage, charging status and other information, comprehensive judgment is made to enter each correction status.

[0116] A method for calculating the SOC of a power battery comprises the following steps:

[0117] like Figure 1 As shown, S01: determine whether the static time after the BMS sleeps is greater than the threshold T1, if so, the initial real SOC is equal to the OCV table SOC value; if not, the initial real SOC is equal to the stored real SOC value;

[0118] S02: Calculate the continuous ampere-hour integral based on the initial real SOC;

[0119] S03: Continue to determine whether the power battery is in a charging state. If so, determine whether the charging process correction condition is met. If so, update the initial real SOC to the SOC discharge process absolute correction value, clear the ampere-hour integral value, and re-execute S02; if not, determine whether the discharge process correction condition is met. If so, update the initial real SOC to the SOC discharge process absolute correction value, clear the ampere-hour integral value, and re-execute S02;

[0120] Specifically, the correction principle is stated as follows: When the battery cell temperature changes little, the battery terminal voltage curve is monotonically increasing or decreasing during the charge and discharge process of the lithium battery at a constant rate, which is consistent with the characteristics of the static OCV curve, that is, there is a corresponding relationship between the terminal voltage and SOC during the charge and discharge process. This relationship can be obtained through battery cell tests, but in the actual charge and discharge process, the battery temperature and charge and discharge rate change rapidly, and the constant charge and discharge rate mentioned in the principle cannot be met, so this relationship cannot be directly used. By analyzing the battery terminal voltage and SO during the charge and discharge process at various temperatures (-30 / -20 / -10 / 0 / 10 / 15 / 25 / 35 / 45 / 55℃) and various charge and discharge rates (0.1C / 0.2C / 0.33C / 0.5C / 0.8C / 1C), the correction principle is as follows: C; during discharge, one or more SOC absolute correction points for the discharge process can be set, through which a two-dimensional table of cell voltages corresponding to each temperature point under multiple discharge rates can be obtained. If, at a discharge rate less than or equal to the discharge rate, the collected cell voltage is less than the voltage corresponding to the temperature in the two-dimensional table, and lasts for several seconds, then the absolute correction condition for the discharge process is met, that is, the set SOC absolute correction point is approximate to the true SOC. The setting of the discharge absolute correction point needs to be determined based on the cell voltage-SOC characteristics. For lithium iron phosphate batteries, due to the presence of a plateau period, it is recommended to select SOC below 30%, and 1 to 3 correction points can be set. For ternary lithium batteries, due to the absence of a plateau period, the discharge process absolute correction point can be set in the entire SOC range.

[0121] When charging, one or more SOC absolute correction points for the charging process can be set. Through the SOC point, a two-dimensional table of cell voltages corresponding to each temperature point under multiple charging rates can be obtained. If the collected cell voltage is greater than the voltage corresponding to the temperature in the two-dimensional table at a discharge rate less than or equal to the discharge rate, and lasts for several seconds, the absolute correction condition for the charging process is met, that is, the set SOC absolute correction point is approximately the real SOC. The setting of the absolute correction point for charging needs to be determined based on the cell voltage-SOC characteristics. For lithium iron phosphate batteries, due to the presence of a plateau period, it is recommended to select more than 90%. For ternary lithium batteries, due to the absence of a plateau period, the absolute correction point for charging can be set in the entire SOC range.

[0122] S04: If the discharge process correction condition or the charging process correction condition is not met, it is determined whether the minimum cell voltage is less than the voltage reference value at the corresponding temperature point. If so, the discharge end SOC self-learning is started;

[0123] S05: Determine whether the highest cell voltage is greater than the voltage reference value at the corresponding temperature point. If so, enter the charging terminal SOC self-learning;

[0124] S06: Output the real SOC and store it in the corresponding NVM;

[0125] S07: Determine whether the stationary time after the BMS sleeps is greater than the threshold value T2 and whether the static OCV table SOC is less than 10% (P1) and whether the result obtained by subtracting the static OCV table SOC from the stored display SOC is greater than 5% (P2);

[0126] S08: If the judgment result of S07 is true, the initial display SOC is equal to the OCV table SOC value; if the judgment result of S07 is false, the initial display SOC is equal to the stored display SOC value;

[0127] S09: performing continuous ampere-hour integral calculation with correction value k based on the initial displayed SOC;

[0128] S10: Determine whether the minimum cell voltage is less than the corresponding temperature point voltage reference value. If so, enter the discharge terminal SOC self-learning; if not, determine whether the maximum cell voltage is greater than the corresponding temperature point voltage reference value. If so, enter the charging terminal SOC self-learning; if not, execute S11;

[0129] S11: Output display SOC and store it in the corresponding NVM;

[0130] S12: Determine whether it is in a non-charging state and whether the deviation between the actual SOC and the displayed SOC is greater than 0.001 (P3);

[0131] S13: Determine whether to enter the discharge OCV acceleration correction or discharge OCV deceleration correction according to the deviation between the displayed SOC and the actual SOC; when the deviation is greater than zero, enter the acceleration correction; when the deviation is less than zero, enter the deceleration correction;

[0132] S14: Determine whether it is in the charging state. If so, enter the charging OCV correction state. When the deviation is greater than zero, enter the charging deceleration correction; when the deviation is less than zero, enter the SOC charging acceleration correction;

[0133] S15: Determine whether it is in a non-charging state, if so, re-enter S13;

[0134] S16: Determine whether the remaining correction amount is less than 0.001 (P5) or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If yes, the correction rate is equal to 1;

[0135] S17: Determine whether the displayed SOC is greater than the absolute correction point of the discharge process and whether the minimum voltage of the single cell is less than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether it is in a non-charging state. If the judgment result is false, enter the waiting state for the discharge process correction condition to be met, and the correction rate is equal to 1;

[0136] S18: If the waiting time of S17 is greater than the threshold value T3, the discharge process is entered and the SOC is accelerated and corrected, and the correction rate k is greater than 1;

[0137] S19: Determine whether it is in charging state, if yes, enter the charging process deceleration correction, and the correction rate is less than 1;

[0138] S20: Determine whether it is in a non-charging state, if so, enter the discharge process and perform SOC acceleration correction;

[0139] S21: Determine whether the remaining correction amount is less than 0.001 (P6) or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If the judgment result is true, the correction rate is equal to 1;

[0140] S22: Determine whether the displayed SOC is less than the SOC at the absolute correction point of the charging process and whether the maximum voltage of the single cell is greater than or equal to the single cell voltage value corresponding to the correction point at each temperature discharge rate and whether the charging rate meets the conditions and is in the charging state;

[0141] S23: If the judgment result of S22 is true, wait for the charging process correction condition to be met, and the correction rate k is equal to 1;

[0142] S24: If the judgment result of S22 is false, the correction rate is equal to 1, and the state enters the uncorrected state;

[0143] S25: If the waiting time in S23 is greater than the threshold value T3, then the charging process SOC is accelerated and corrected, and the correction rate k is greater than 1;

[0144] S26: If the state is not charging, then the SOC deceleration correction during the discharge process is performed, and the correction rate k is less than 1;

[0145] S27: If the remaining correction amount is less than 0.001 (P4) or the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered, the correction rate k is equal to 1.

[0146] Specifically,

[0147] In S02, the ampere-hour integral is calculated according to the following formula:

[0148]

[0149] Among them, SOCReal t is the current real SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery.

[0150] Specifically,

[0151] In S09, the ampere-hour integral is calculated according to the following formula:

[0152]

[0153] Among them, SOCDisplay t is the current displayed SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery, k is the SOC correction rate, where, if k is equal to 1, there is no correction for the ampere-hour integral; if k is greater than 1, charging is corrected for deceleration and discharging is corrected for acceleration; if k is less than 1, charging is corrected for acceleration and discharging is corrected for deceleration.

[0154] Specifically,

[0155] In S03, if the charging process correction condition is met, the discharge process SOC acceleration correction in S18 is performed, and the correction rate k is greater than 1;

[0156] In S03, if the charging process correction condition is met, the charging process SOC acceleration correction in S25 is performed, and the correction rate k is greater than 1;

[0157] Specifically,

[0158] In S04, the voltage reference value at the corresponding temperature point is obtained by linearly interpolating the temperature, discharge rate and the single cell voltage MAP corresponding to the low SOC point, wherein the SOC is 3%, and the single cell voltage corresponding to the SOC of 3% is discharged at a rate of 0.1C, 0.2C, and 0.33C at each temperature point, forming a linear interpolation MAP of the voltage reference value at the corresponding temperature point.

[0159] Specifically,

[0160] In S05, the voltage reference value at the corresponding temperature point is obtained by linearly interpolating the temperature, charging rate and the single cell voltage MAP corresponding to the high SOC point, where the SOC is 97%, and the single cell voltage corresponding to the SOC of 97% is charged at a rate of 0.1c, 0.2c, 0.33c, 0.5c, 0.8c, and 1c at each temperature point, forming a linear interpolation MAP of the voltage reference value at the corresponding temperature point.

[0161] Specifically,

[0162] In S04, if not, directly execute S05;

[0163] In S05, if not, directly execute S06.

[0164] Specifically,

[0165] In S03, it is determined whether the charging process correction condition is met, and if so, the initial real SOC is updated to 90%; it is determined whether the discharging process correction condition is met, and if so, the initial real SOC is updated to 30%;

[0166] In S01, the threshold T1 is 2h;

[0167] In S07, the threshold T2 is 2h;

[0168] In S18, the threshold value T3 is 10s.

[0169] The present invention also provides a SOC calculation device for a power battery, comprising:

[0170] The first judgment module is used to judge whether the static time after the BMS sleeps is greater than the threshold value T1. If so, the initial real SOC is equal to the OCV table SOC value; if not, the initial real SOC is equal to the stored real SOC value;

[0171] A first calculation module, used for performing continuous ampere-hour integral calculation based on an initial real SOC;

[0172] The second judgment module is used to continuously judge whether the power battery is in a charging state. If so, it is judged whether the charging process correction condition is met. If so, the initial real SOC is updated to the SOC discharge process absolute correction value, and the ampere-hour integral value is cleared, and the first calculation module is re-executed; if not, it is judged whether the discharge process correction condition is met. If so, the initial real SOC is updated to the SOC discharge process absolute correction value, and the ampere-hour integral value is cleared, and the second judgment module is re-executed;

[0173] The third judgment module is used to judge whether the minimum cell voltage is less than the voltage reference value of the corresponding temperature point if the discharge process correction condition or the charging process correction condition is not met, and if so, enter the discharge end SOC self-learning;

[0174] The fourth judgment module is used to judge whether the highest single cell voltage is greater than the voltage reference value of the corresponding temperature point. If so, the charging terminal SOC self-learning is started;

[0175] A first output module, used for outputting the real SOC and storing it in the corresponding NVM;

[0176] The fifth judgment module is used to judge whether the static time after the BMS sleeps is greater than the threshold value T2 and whether the static OCV table SOC is less than 10% (P1) and whether the result obtained by subtracting the static OCV table SOC from the stored display SOC is greater than 5% (P2); if the judgment result of S07 is true, the initial display SOC is equal to the OCV table SOC value; if the judgment result of S07 is false, the initial display SOC is equal to the stored display SOC value;

[0177] A second calculation module, used for performing continuous ampere-hour integral calculation with a correction value k based on the initial displayed SOC;

[0178] The seventh judgment module is used to judge whether the minimum cell voltage is less than the corresponding temperature point voltage reference value. If so, the discharge terminal SOC self-learning is started; if not, the maximum cell voltage is judged to be greater than the corresponding temperature point voltage reference value. If so, the charging terminal SOC self-learning is started; if not, the second output module is executed;

[0179] The second output module is used to output the display SOC and store it in the corresponding NVM;

[0180] The eighth judgment module is used to judge whether it is in a non-charging state and whether the deviation between the actual SOC and the displayed SOC is greater than 0.001 (P3); according to the deviation between the displayed SOC and the actual SOC, determine whether to enter the discharge OCV acceleration correction or the discharge OCV deceleration correction; when the deviation is greater than zero, enter the acceleration correction; when the deviation is less than zero, enter the deceleration correction;

[0181] The ninth judgment module is used to judge whether it is in the charging state. If it is, it enters the charging OCV correction state. When the deviation is greater than zero, it enters the charging deceleration correction; when the deviation is less than zero, it enters the SOC charging acceleration correction;

[0182] A tenth judging module is used to judge whether the device is in a non-charging state, and if so, re-enter the eighth judging module;

[0183] The eleventh judgment module is used to judge whether the remaining correction amount is less than 0.001 (P5) or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If yes, the correction rate is equal to 1;

[0184] The twelfth judgment module is used to judge whether the displayed SOC is greater than the absolute correction point of the discharge process and whether the minimum voltage of the single cell is less than or equal to the single cell voltage value corresponding to the correction point in the table under each temperature discharge rate and whether it is in a non-charging state. If the judgment result is false, it enters the waiting state for the discharge process correction condition to be met, and the correction rate is equal to 1;

[0185] A thirteenth judgment module is used to enter the discharge process SOC acceleration correction if the waiting time of the twelfth judgment module is greater than the threshold T3, and the correction rate k is greater than 1;

[0186] A fourteenth judgment module is used to judge whether it is in a charging state. If so, the charging process is decelerated and corrected, and the correction rate is less than 1;

[0187] A fifteenth judgment module is used to judge whether it is in a non-charging state, and if so, enter the discharge process SOC acceleration correction;

[0188] A sixteenth judgment module is used to judge whether the remaining correction amount is less than 0.001 (P6) or whether to enter the charging terminal SOC self-learning state or whether to enter the discharging terminal SOC self-learning state. If the judgment result is true, the correction rate is equal to 1;

[0189] The seventeenth judgment module is used to judge whether the displayed SOC is less than the SOC at the absolute correction point of the charging process and whether the maximum voltage of the single cell is greater than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether the charging rate meets the conditions and whether it is in the charging state; if the judgment result of S22 is true, wait for the charging process correction conditions to be met, and the correction rate k is equal to 1; if the judgment result of S22 is false, the correction rate is equal to 1, and enters the uncorrected state;

[0190] An eighteenth judgment module, configured to perform an accelerated correction of the SOC during the charging process if the waiting time in the seventeenth judgment module is greater than a threshold value T3, and a correction rate k is greater than 1;

[0191] The nineteenth judgment module, if the state is not charging, performs SOC deceleration correction during the discharge process, and the correction rate k is less than 1;

[0192] The twentieth judgment module is used to determine that if the remaining correction amount is less than 0.001 (P4) or the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered, the correction rate k is equal to 1.

[0193] Specifically,

[0194] In the first calculation module, the ampere-hour integral calculation is performed according to the following formula:

[0195]

[0196] Among them, SOCReal t is the current real SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery.

[0197] Specifically,

[0198] In the second calculation module, the ampere-hour integral calculation is performed according to the following formula:

[0199]

[0200] Among them, SOCDisplay t is the current displayed SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery, k is the SOC correction rate, where, if k is equal to 1, there is no correction for the ampere-hour integral; if k is greater than 1, charging is corrected for deceleration and discharging is corrected for acceleration; if k is less than 1, charging is corrected for acceleration and discharging is corrected for deceleration.

[0201] Specifically,

[0202] In the second judgment module, if the charging process correction condition is met, the discharge process SOC acceleration correction in S18 is performed, and the correction rate k is greater than 1;

[0203] In S03, if the charging process correction condition is met, the charging process SOC acceleration correction in S25 is performed, and the correction rate k is greater than 1.

[0204] Specifically,

[0205] In the third judgment module, the voltage reference value of the corresponding temperature point is obtained by linearly interpolating the temperature, the discharge rate and the single cell voltage MAP corresponding to the low SOC point, wherein the SOC is 3%, and the single cell voltage corresponding to the SOC of 3% at each temperature point at a discharge rate of 0.1C, 0.2C, and 0.33C constitutes the linear interpolation MAP of the voltage reference value of the corresponding temperature point.

[0206] Specifically,

[0207] In the fourth judgment module, the voltage reference value of the corresponding temperature point is obtained by linearly interpolating the temperature, the charging rate and the single cell voltage MAP corresponding to the high SOC point, wherein the SOC is 97%, and each temperature point is charged at a rate of 0.1c, 0.2c, 0.33c, 0.5c, 0.8c, and 1c, corresponding to the single cell voltage of 97% SOC, forming the linear interpolation MAP of the voltage reference value of the corresponding temperature point.

[0208] Specifically,

[0209] In the third judgment module, if no, directly execute the fourth judgment module;

[0210] In the fourth judgment module, if not, the fifth judgment module is directly executed.

[0211] Specifically,

[0212] In the second judgment module, it is judged whether the charging process correction condition is met, and if so, the initial real SOC is updated to 90%; it is judged whether the discharging process correction condition is met, and if so, the initial real SOC is updated to 30%.

[0213] In the first judgment module, the threshold T1 is 2h;

[0214] In the fifth judgment module, the threshold T2 is 2h;

[0215] In the thirteenth judgment module, the threshold T3 is 10s.

[0216] The present invention also provides an electric vehicle, comprising the SOC calculation device of the power battery as described above.

Claims

1. A method for calculating the SOC of a power battery, characterized in that: It includes three parts: real SOC calculation, displayed SOC calculation and SOC correction status management; The actual SOC calculation is used to characterize the actual remaining power of the power battery. The deviation between the actual SOC and the displayed SOC is used as one of the conditions for selecting the displayed SOC correction rate k. Once the actual SOC value meets the correction condition, it directly jumps to the SOC correction target value. The display SOC calculation is used for the instrument to display the current remaining power of the power battery and the vehicle controller to calculate the remaining cruising range. The displayed SOC value changes smoothly during the charging and discharging process without correction mutations; The SOC correction state management is to enter each correction state based on the actual SOC, displayed SOC, cell voltage, and charging state; The actual SOC calculation comprises the steps of: S01: Determine whether the stationary time after the BMS sleep is greater than the threshold T1. If so, take the initial real SOC equal to the OCV table SOC value; if not, take the initial real SOC equal to the stored real SOC value; S02: performing continuous ampere-hour integral calculation based on the initial real SOC; S03: continuously determining whether the power battery is in a charging state; if so, determining whether a charging process correction condition is satisfied; if so, updating the initial real SOC to an absolute correction value of the SOC charging process, clearing the ampere-hour integral value, and re-executing S02; if not, determining whether a discharge process correction condition is satisfied; if so, updating the initial real SOC to an absolute correction value of the SOC discharge process, clearing the ampere-hour integral value, and re-executing S02; S04: Continuously determine whether the minimum cell voltage is less than the voltage reference value at the corresponding temperature point. If so, enter the discharge end SOC self-learning; S05: Determine whether the highest cell voltage is greater than the voltage reference value at the corresponding temperature point. If so, enter the charging terminal SOC self-learning; S06: Output the real SOC and store it in the corresponding NVM; The display SOC calculation comprises the steps of: S07: Determine whether the stationary time after the BMS is dormant is greater than a threshold value T2 and whether the static OCV table SOC is less than P1 and whether the result obtained by subtracting the static OCV table SOC from the stored display SOC is greater than P2; S08: If the judgment result of S07 is true, the initial displayed SOC is equal to the OCV table SOC value; If the judgment result of S07 is false, the initial display SOC is equal to the stored display SOC value; S09: performing continuous ampere-hour integral calculation with correction value k based on the initial display SOC; S10: Determine whether the minimum cell voltage is less than the corresponding temperature point voltage reference value. If so, enter the discharge terminal SOC self-learning; if not, determine whether the maximum cell voltage is greater than the corresponding temperature point voltage reference value. If so, enter the charging terminal SOC self-learning; If not, execute S11; S11: Output display SOC and store it in the corresponding NVM; The SOC correction state management comprises the steps of: S12: Determine whether it is in a non-charging state and whether the deviation between the actual SOC and the displayed SOC is greater than P3; S13: determining whether to enter into a discharge OCV acceleration correction or a discharge OCV deceleration correction according to the deviation between the displayed SOC and the actual SOC; when the deviation is greater than zero, entering into an acceleration correction; when the deviation is less than zero, entering into a deceleration correction; S14: Determine whether it is in the charging state. If so, enter the charging OCV correction state. When the deviation is greater than zero, enter the charging deceleration correction state; when the deviation is less than zero, enter the SOC charging acceleration correction state. S15: Determine whether it is in a non-charging state, if so, re-enter S13; S16: Determine whether the remaining correction amount is less than P5 or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If yes, the correction rate is equal to 1; S17: Determine whether the displayed SOC is greater than the absolute correction point of the discharge process and whether the minimum voltage of the single cell is less than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether it is in a non-charging state. If the judgment result is false, enter the waiting state for the discharge process correction condition to be met, and the correction rate is equal to 1; S18: If the waiting time of S17 is greater than the threshold value T3, the discharge process is started and the SOC is accelerated and corrected, and the correction rate k is greater than 1; S19: Determine whether it is in charging state, if yes, enter the charging process deceleration correction, and the correction rate is less than 1; S20: Determine whether it is in a non-charging state, if so, enter the discharge process and perform SOC acceleration correction; S21: Determine whether the remaining correction amount is less than P6 or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If the judgment result is true, the correction rate is equal to 1; S22: Determine whether the displayed SOC is less than the SOC at the absolute correction point of the charging process and whether the maximum voltage of the single cell is greater than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether the charging rate meets the conditions and is in the charging state; S23: If the judgment result of S22 is true, wait for the charging process correction condition to be met, and the correction rate k is equal to 1; S24: If the judgment result of S22 is false, the correction rate is equal to 1, and the state is entered into an uncorrected state; S25: If the waiting time in S23 is greater than the threshold value T3, then the charging process SOC is accelerated and the correction rate k is greater than 1; S26: If the state is not charging, then the SOC deceleration correction during the discharge process is performed, and the correction rate k is less than 1; S27: If the remaining correction amount is less than P4 or the charging terminal SOC self-learning state is entered or the discharging terminal SOC self-learning state is entered, the correction rate k is equal to 1.

2. The method for calculating the SOC of a power battery according to claim 1, characterized in that: In the S02, the ampere-hour integral calculation is performed according to the following formula: Among them, SOCReal t is the current real SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery.

3. The method for calculating the SOC of a power battery according to claim 1, characterized in that: In S09, the ampere-hour integral is calculated according to the following formula: Among them, SOCDisplay t is the current displayed SOC, I is the bus current of the power battery, Kt is the charge and discharge efficiency, Cap toatl is the nominal total capacity of the battery, k is the SOC correction rate, where, if k is equal to 1, there is no correction for the ampere-hour integral; if k is greater than 1, charging is corrected for deceleration and discharging is corrected for acceleration; if k is less than 1, charging is corrected for acceleration and discharging is corrected for deceleration.

4. The method for calculating the SOC of a power battery according to claim 1, characterized in that: In S03, if the discharge process correction condition is met, the discharge process SOC acceleration correction in S18 is performed, and the correction rate k is greater than 1; In S03, if the charging process correction condition is met, the charging process SOC acceleration correction in S25 is performed, and the correction rate k is greater than 1; In the S04, the voltage reference value at the corresponding temperature point is obtained by linearly interpolating the temperature, the discharge rate and the single cell voltage MAP corresponding to the low SOC point, wherein the SOC is 3%, and the single cell voltage corresponding to the SOC of 3% is discharged at the rates of 0.1C, 0.2C and 0.33C at each temperature point, forming the linear interpolation MAP of the voltage reference value at the corresponding temperature point; In the S05, the voltage reference value at the corresponding temperature point is obtained by linearly interpolating the temperature, the charging rate and the single cell voltage MAP corresponding to the high SOC point, wherein the SOC is 97%, and the single cell voltage corresponding to the SOC of 97% is charged at the rates of 0.1c, 0.2c, 0.33c, 0.5c, 0.8c and 1c at each temperature point, forming the linear interpolation MAP of the voltage reference value at the corresponding temperature point; In said S04, if no, then directly execute S05; In said S05, if no, then directly execute S06; In S03, it is determined whether the charging process correction condition is met, and if so, the initial real SOC is updated to 90%; it is determined whether the discharging process correction condition is met, and if so, the initial real SOC is updated to 30%.

5. A SOC calculation device for a power battery, characterized in that: include: Real SOC calculation module, displayed SOC calculation module and SOC correction status management module; The real SOC calculation module is used to characterize the real remaining power of the power battery. The deviation between the real SOC and the displayed SOC is used as one of the conditions for selecting the displayed SOC correction rate k. Once the real SOC value meets the correction condition, it directly jumps to the SOC correction target value. The display SOC calculation module is used for the instrument to display the current remaining power of the power battery and the vehicle controller to calculate the remaining cruising range, and the displayed SOC value changes smoothly during the charging and discharging process without correction mutations; The SOC correction state management module is used to comprehensively judge and enter each correction state according to the real SOC, displayed SOC, cell voltage, and charging state; The real SOC calculation module includes: The first judgment module is used to judge whether the static time after the BMS sleeps is greater than the threshold value T1. If so, the initial real SOC is equal to the OCV table SOC value; if not, the initial real SOC is equal to the stored real SOC value; A first calculation module, configured to perform continuous ampere-hour integral calculation based on the initial real SOC; a second judgment module, for continuously judging whether the power battery is in a charging state; if so, judging whether a charging process correction condition is satisfied; if so, updating the initial real SOC to an absolute correction value of the SOC discharge process, clearing the ampere-hour integral value, and re-executing the first calculation module; if not, judging whether a discharge process correction condition is satisfied; if so, updating the initial real SOC to an absolute correction value of the SOC discharge process, clearing the ampere-hour integral value, and re-executing the second judgment module; The third judgment module is used to judge whether the minimum cell voltage is less than the voltage reference value of the corresponding temperature point if the discharge process correction condition or the charging process correction condition is not met, and if so, enter the discharge end SOC self-learning; The fourth judgment module is used to judge whether the highest single cell voltage is greater than the voltage reference value of the corresponding temperature point. If so, the charging terminal SOC self-learning is started; A first output module, used for outputting the real SOC and storing it in the corresponding NVM; The display SOC calculation module includes: A fifth judgment module is used to judge whether the static time after the BMS is dormant is greater than a threshold value T2 and whether the static OCV table SOC is less than P1 and whether the result obtained by subtracting the static OCV table SOC from the stored display SOC is greater than P2; if the judgment result is true, the initial display SOC is equal to the OCV table SOC value; if the judgment result is false, the initial display SOC is equal to the stored display SOC value; A second calculation module, configured to perform continuous ampere-hour integral calculation with a correction value k based on the initial displayed SOC; The seventh judgment module is used to judge whether the minimum cell voltage is less than the corresponding temperature point voltage reference value. If so, the discharge terminal SOC self-learning is started; if not, the maximum cell voltage is judged to be greater than the corresponding temperature point voltage reference value. If so, the charging terminal SOC self-learning is started; if not, the second output module is executed; The second output module is used to output the display SOC and store it in the corresponding NVM; The SOC correction state management module includes: An eighth judgment module is used to judge whether it is a non-charging state and whether the deviation between the real SOC and the displayed SOC is greater than P3; according to the deviation between the displayed SOC and the real SOC, determine whether to enter the discharge OCV acceleration correction or the discharge OCV deceleration correction; when the deviation is greater than zero, enter the acceleration correction; when the deviation is less than zero, enter the deceleration correction; The ninth judgment module is used to judge whether it is in the charging state. If so, it enters the charging OCV correction state. When the deviation is greater than zero, it enters the charging deceleration correction; when the deviation is less than zero, it enters the SOC charging acceleration correction; A tenth judging module, used for judging whether the battery is in a non-charging state, and if so, re-entering the eighth judging module; An eleventh judgment module is used to judge whether the remaining correction amount is less than P5 or whether the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state is entered. If yes, the correction rate is equal to 1; The twelfth judgment module is used to judge whether the displayed SOC is greater than the absolute correction point of the discharge process and whether the minimum voltage of the single cell is less than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether it is in a non-charging state. If the judgment result is false, the process enters the waiting state for the discharge process correction condition to be met, and the correction rate is equal to 1; A thirteenth judgment module, configured to enter the discharge process SOC acceleration correction if the waiting time of the twelfth judgment module is greater than a threshold value T3, and the correction rate k is greater than 1; A fourteenth judgment module is used to judge whether it is in a charging state. If so, the charging process is decelerated and corrected, and the correction rate is less than 1; A fifteenth judgment module is used to judge whether it is in a non-charging state, and if so, enter the discharge process SOC acceleration correction; A sixteenth judgment module is used to judge whether the remaining correction amount is less than P6 or whether to enter the charging terminal SOC self-learning state or the discharging terminal SOC self-learning state. If the judgment result is true, the correction rate is equal to 1; The seventeenth judgment module is used to judge whether the displayed SOC is less than the SOC at the absolute correction point of the charging process and whether the maximum voltage of the single cell is greater than or equal to the single cell voltage value corresponding to the correction point in the table at each temperature discharge rate and whether the charging rate meets the conditions and whether it is in the charging state; if the judgment result is true, wait for the charging process correction conditions to be met, and the correction rate k is equal to 1; if the judgment result is false, the correction rate is equal to 1, and enters the uncorrected state; An eighteenth judgment module, configured to perform an accelerated correction of the SOC during the charging process if the waiting time in the seventeenth judgment module is greater than a threshold value T3, and a correction rate k is greater than 1; The nineteenth judgment module, if the state is not charging, performs SOC deceleration correction during the discharge process, and the correction rate k is less than 1; The twentieth judgment module is used to determine that if the remaining correction amount is less than P4 or the charging terminal SOC self-learning state is entered or the discharging terminal SOC self-learning state is entered, the correction rate k is equal to 1.

6. An electric vehicle, characterized in that: A SOC calculation device for a power battery comprising the method according to claim 5.

Images