CN114355207A - SOC calculation method, device and electric vehicle of a power battery - Google Patents

Abstract

The invention relates to a SOC calculation method, device and electric vehicle of a power battery. The method includes the following steps: S01: judging whether the static time after the BMS sleeps is greater than a threshold value T1, and if so, the initial real SOC is equal to the OCV look-up table SOC value; No, the initial real SOC is equal to the stored real SOC value; S02: Perform continuous ampere-hour integral calculation based on the initial real SOC; S03: Continue to judge whether the power battery is in a charging state, if so, judge whether the charging process correction condition is met, if yes, then Update the initial real SOC to be the absolute correction value of the SOC charging process, and clear the ampere-hour integral value, and execute S02 again; if not, determine whether the correction conditions for the discharge process are met; if so, update the initial real SOC to the absolute correction value of the SOC discharge process, And clear the ampere-hour integral value, and execute S02 again. The present invention can correctly estimate the SOC, make the displayed SOC infinitely close to the real SOC, and can prevent jumping during the SOC correction process.

Description

SOC calculation method, device and electric vehicle of a power battery

technical field

The invention relates to the technical field of power battery management systems, in particular to the SOC calculation technology of power batteries and electric vehicles.

Background technique

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 charging and discharging, SOC, SOH, SOP and other systems of the battery system. SOC is one of the most important ones. The parameters that characterize the remaining charge of the power battery are directly related to the calculation of the cruising range of the whole vehicle, and are directly related to the user experience. Because the operating environment, working conditions, and electrochemical characteristics of the battery itself are relatively complex for new energy vehicles, and there is no corresponding measurement. Quantity can directly have a relatively robust and exact relationship with SOC, which brings great difficulties to accurate SOC estimation. Improving the accuracy of SOC estimation has become one of the topics that many manufacturers have overcome.

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. , it can only enter after the power battery pack has been stationary for a period of time; second, due to the existence of the current sensor acquisition error, there is a large cumulative error in the long-term ampere-hour integration, especially in the long-term shallow charging and shallow discharging conditions; third , after the battery power decays, the estimated SOC and the actual SOC have a large deviation; fourth, there is a jump in the SOC correction process.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a SOC calculation method, device and electric vehicle of a power battery, and the technical problems solved:

First, the accumulation of ampere-hour points for a long time leads to inaccurate SOC estimation;

Second, there are jumps in the SOC correction process.

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

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 look-up table SOC value; if not, the initial real SOC is equal to the stored real SOC value;

S02: Perform continuous ampere-hour integral calculation based on the initial real SOC;

S03: Continue to judge whether the power battery is in a charged state, and if so, judge whether the charging process correction condition is met, and if so, update the initial real SOC to the absolute correction value of the SOC discharge process, clear the ampere-hour integral value, and re-execute the above S02; if not, judge whether the discharge process correction condition is met, if so, update the initial real SOC to be the absolute correction value of the SOC discharge process, clear the ampere-hour integral value, and re-execute the S02;

S04: If the discharge process correction conditions are not met or the charging process correction conditions are not met, judge whether the minimum cell voltage is less than the reference voltage value at the corresponding temperature point, and if so, enter the discharge end SOC self-learning;

S05: Determine whether the highest cell voltage is greater than the reference value of the voltage at the corresponding temperature point, and if so, enter the charging end SOC self-learning;

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

S07: Determine whether the static time after the BMS sleeps is greater than the threshold T2 and whether the static OCV look-up table SOC is less than P1 (P1 is 10%), and store and display whether the result obtained by subtracting the static OCV look-up SOC from the static OCV table SOC is greater than P2 (P2 is 5%);

S08: If the judgment result of the S07 is true, the initial display SOC is equal to the OCV look-up table SOC value; if the judgment result of the S07 is false, the initial display SOC is equal to the stored display SOC value;

S09: Perform continuous ampere-hour integral calculation with correction value k based on the initially displayed SOC;

S10: Determine whether the minimum cell voltage is less than the reference voltage value at the corresponding temperature point, if so, enter the discharge end SOC self-learning; if not, determine whether the highest cell voltage is greater than the corresponding temperature point voltage reference value, if so, enter the charging end SOC self-learning; if not, execute S11;

S11: The output shows the SOC and stores it in the corresponding NVM;

S12: Determine 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);

S13: 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;

S14: Determine whether it is a 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;

S15: Determine whether it is in a non-charging state, and if so, re-enter the S13;

S16: Determine whether the remaining correction amount is less than P5 (P5 is 0.001) or whether it enters the end-of-charge SOC self-learning state or whether it enters the discharge-end SOC self-learning state, if so, 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 cell voltage is less than or equal to the cell voltage value corresponding to the correction point of the table look-up correction point under each temperature discharge rate and whether it is in a non-charging state, if the judgment result is false, then Enter and wait for the correction condition of the discharge process to be satisfied, and the correction rate is equal to 1;

S18: If the waiting time in S17 is greater than the threshold value T3, enter the discharge process SOC acceleration correction, and the correction rate k is greater than 1;

S19: determine whether it is in the charging state, if so, enter the charging process to decelerate and correct, and the correction rate is less than 1;

S20: Determine whether it is in a non-charging state, and if so, enter the SOC acceleration correction in the discharging process;

S21: Determine whether the remaining correction amount is less than P6 (P6 is 0.001) or whether it enters the SOC self-learning state at the end of charging or whether it enters the self-learning state of the SOC at the end of discharge. If the judgment result is true, the correction rate is equal to 1;

S22: judging whether the displayed SOC is less than the absolute correction point SOC of the charging process and whether the maximum cell voltage is greater than or equal to the cell voltage value corresponding to the correction point in the table look-up table under each temperature discharge rate, and whether the charging rate meets the conditions and is in a charging state;

S23: If the judgment result of S22 is true, wait for the charging process correction condition to be satisfied, 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 uncorrected state is entered;

S25: If the waiting time in S23 is greater than the threshold value T3, perform SOC acceleration correction during the charging process, and the correction rate k is greater than 1;

S26: If it is in a non-charging state, perform SOC deceleration correction during the discharge process, and the correction rate k is less than 1;

S27: If the remaining correction amount is less than P4 (P4 is 0.001) or enters the end-of-charge SOC self-learning state or enters the end-of-discharge SOC self-learning state, the correction rate k is equal to 1.

Preferably,

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

其中，SOCReal_t为当前真实SOC，I为动力电池母线电流，Kt为充放电效率，Cap_toatl为电池标称总容量。

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, and Cap _toatl is the nominal total capacity of the battery.

Preferably,

In the S09, the ampere-hour integral calculation is performed 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, and k is the SOC correction rate. If k is equal to 1, the ampere-hour integral is not corrected; If k is greater than 1, charging is deceleration correction, and discharging is acceleration correction; if k is less than 1, charging is acceleration correction, and discharging is deceleration correction.

Preferably,

In the S03, if the charging process correction condition is satisfied, the SOC acceleration correction in the discharging process in the S18 is performed, and the correction rate k is greater than 1;

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

Preferably,

In the S04, the voltage reference value corresponding to the temperature point is obtained by linearly interpolating the temperature, the discharge rate and the cell voltage MAP corresponding to the low SOC point, wherein the SOC is 3%, and each temperature point is 0.1C, 0.2C, 0.33 The C rate discharge corresponds to the cell voltage with SOC of 3%, which constitutes the linear interpolation MAP of the voltage reference value at the corresponding temperature point.

Preferably,

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

Preferably,

In the S04, if not, then directly execute S05;

In the S05, if not, then directly execute S06.

Preferably,

In the S03, it is judged whether the charging process correction condition is satisfied, and if so, the initial real SOC is updated to be 90%; it is judged whether the discharge process correction condition is satisfied, and if so, the initial real SOC is updated to 30%;

In the S01, the threshold T1 is 2h;

In the S07, the threshold T2 is 2h;

In the S18, the threshold value T3 is 10s.

The present invention also provides an SOC calculation device for a power battery, comprising:

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 look-up 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;

The second judging module is used to continuously judge whether the power battery is in a charging state, and if so, judge whether the charging process correction condition is met, and if so, update the initial real SOC to be the absolute correction value of the SOC discharge process, and clear the ampere-hour integral value , re-execute the first calculation module; if not, determine whether the discharge process correction condition is met, if so, update the initial real SOC to the absolute correction value of the SOC discharge process, clear the ampere-hour integral value, and re-execute the above the second judgment module;

The third judging module is used for judging whether the minimum cell voltage is less than the reference value of the voltage at the corresponding temperature point if the discharge process correction condition is not satisfied or the charging process correction condition is not satisfied, and if so, enter the discharge end SOC self-learning;

The fourth judgment module is used to judge whether the highest cell voltage is greater than the reference value of the voltage at the corresponding temperature point, and if so, enter the self-learning of the SOC at the charging end;

The first output module is used to output the real SOC and store it in the corresponding NVM;

The fifth judgment module is used to judge whether the static time after BMS sleep is greater than the threshold value T2 and whether the static OCV look-up table SOC is less than P1 (P1 is 10%) and whether the result obtained by subtracting the static OCV look-up 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 look-up table SOC value; if the judgment result of S07 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 initially displayed SOC;

The seventh judgment module is used to judge whether the minimum cell voltage is less than the reference value of the voltage at the corresponding temperature point, if so, enter the discharge end SOC self-learning; if not, judge whether the maximum cell voltage is greater than the reference value of the voltage at the corresponding temperature point, if so , then enter the charging end SOC self-learning; if not, execute the second output module;

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

The 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 (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 discharge OCV deceleration correction; when the deviation is greater than zero, enter acceleration correction; when the deviation is less than zero, enter deceleration correction;

The ninth judgment module is used for judging whether it is a 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;

The tenth judgment module is used to judge whether it is in a non-charging state, and if so, re-enter the eighth judgment module;

The eleventh judgment module is used to judge whether the remaining correction amount is less than P5 (P5 is 0.001) or whether it enters the self-learning state of SOC at the end of charging or whether it enters the self-learning state of SOC at the end of discharge. If so, the correction rate is equal to 1;

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

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

The fourteenth judging module is used to judge whether it is in the charging state, if so, enter the charging process to decelerate and correct, and the correction rate is less than 1;

The fifteenth judging module is used to judge whether it is in a non-charging state, and if so, enter the SOC acceleration correction in the discharging process;

The sixteenth judgment module is used to judge whether the remaining correction amount is less than P6 (P6 is 0.001) or whether it has entered the charging end SOC self-learning state or whether it has entered the discharging end SOC self-learning state. If the judgment result is true, the correction rate is equal to 1;

The seventeenth judging 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 cell voltage is greater than or equal to the cell voltage value corresponding to the correction point of the look-up table under the discharge rate of each temperature and whether the charging rate satisfies the conditions and Whether it is in a charging state; if the judgment result of S22 is true, wait for the charging process correction condition to be satisfied, 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;

An eighteenth judging module, configured to perform a charging process SOC acceleration correction if the waiting time in the seventeenth judging module is greater than the threshold value T3, and the correction rate k is greater than 1;

The nineteenth judging module, if it is in a non-charging state, performs SOC deceleration correction during the discharge process, and the correction rate k is less than 1;

The twentieth judging module is used for the correction rate k equal to 1 if the remaining correction amount is less than P4 (P4 is 0.001) or enters the end-of-charge SOC self-learning state or enters the end-of-discharge SOC self-learning state.

Preferably,

In the first calculation module, 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, and Cap _toatl is the nominal total capacity of the battery.

Preferably,

In the second calculation module, the ampere-hour integral calculation is performed 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, and k is the SOC correction rate. If k is equal to 1, the ampere-hour integral is not corrected; If k is greater than 1, charging is deceleration correction, and discharging is acceleration correction; if k is less than 1, charging is acceleration correction, and discharge is deceleration correction.

Preferably,

In the second judgment module, if the charging process correction condition is satisfied, the SOC acceleration correction in the discharging process in S18 is performed, and the correction rate k is greater than 1;

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

Preferably,

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

Preferably,

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

Preferably,

In the third judgment module, if not, then directly execute the fourth judgment module;

In the fourth judging module, if no, the fifth judging module is directly executed.

Preferably,

In the second judging module, it is judged whether the charging process correction condition is met, and if so, the initial real SOC is updated to be 90%; it is judged whether the discharge process correction condition is met, and if so, the initial real SOC is updated to 30% .

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

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

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

The present invention also provides an electric vehicle, including the above-mentioned SOC calculation device of the power battery.

By adopting the above-mentioned technical scheme, the beneficial effects that the present invention can achieve are:

First, when the BMS is powered on, it enters the 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, the absolute correction point and multi-condition SOC of the multi-condition SOC discharge process are set. The absolute correction point of the charging process; the SOC correction strategy of the above sections can effectively solve the problem of inaccurate SOC estimation caused by the accumulated error of the long-term ampere-hour integration.

Second, using the normalization method, the BMS looks up the table to select different correction rates k according to the SOC correction state and the deviation between the displayed SOC and the real SOC. While adjusting the displayed SOC smoothly, it quickly approaches the real SOC and solves the SOC correction process. jump problem.

Description of drawings

Figure 1 is a flow chart of real SOC calculation;

Figure 2 is a flow chart showing the calculation of SOC;

FIG. 3 is a flowchart of SOC correction state management.

Detailed ways

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

The SOC calculation method for a power battery described in the present invention is generally divided into three large modules, including real SOC calculation, displayed SOC calculation and SOC correction state management.

Real SOC calculation module: It is used to characterize the current remaining real power of the power battery, and the deviation of the SOC is displayed through the rest as one of the conditions for selecting and displaying the SOC correction rate k. Once the value meets the correction conditions, it directly jumps to the SOC correction target value.

Display SOC calculation module: used for the instrument to display the current remaining power of the power battery and the VCU (vehicle controller) to calculate the remaining cruising range. This value changes smoothly in the ancient city of charging and discharging, and there is no correction and sudden change.

SOC correction state management: According to the real SOC, display SOC, cell voltage, charging state and other information, comprehensively judge to enter each correction state.

A method for calculating the SOC of a power battery, comprising the following steps:

As shown in Figure 1, 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 look-up table SOC value; if not, the initial real SOC is equal to the stored real SOC value;

S02: Perform continuous ampere-hour integral calculation based on the initial real SOC;

S03: Continue to judge whether the power battery is in a state of charge, and if so, judge whether the charging process correction condition is met, if so, update the initial real SOC to the absolute correction value of the SOC discharge process, and clear the ampere-hour integral value, and execute S02 again; if not , then judge whether the discharge process correction condition is satisfied, and if so, update the initial real SOC to be the absolute correction value of the SOC discharge process, clear the ampere-hour integral value, and execute S02 again;

Specifically, the correction principle is stated as follows: when the temperature of the battery cell changes slightly, the battery terminal voltage curve increases or decreases monotonically during the charging and discharging process at a constant rate, which is consistent with the characteristics of the static OCV curve, that is, the charging and discharging process terminal There is a corresponding relationship between voltage and SOC. This relationship can be obtained through cell tests. However, in the actual charging and discharging process, the battery temperature and charging and discharging rate change rapidly, which cannot meet the constant charging and discharging rate mentioned in the principle, so this relationship cannot be directly Application, through the analysis of each temperature (-30/-20/-10/0/10/15/25/35/45/55℃), each charge and discharge rate (0.1C/0.2C/0.33C/0.5C/0.8 The relationship between the battery terminal voltage and SOC during the charging and discharging process under C/1C); during discharging, one or more absolute correction points for the SOC during the discharging process can be set, and the SOC corresponding to each temperature point under multiple discharge rates can be obtained through the SOC point. Two-dimensional table of core voltage, if the collected cell voltage is less than or equal to the discharge rate, the voltage of the collected cell is less than the voltage corresponding to the above two-dimensional table according to the temperature, and lasts for several seconds, the absolute correction condition of the discharge process is satisfied, that is, the set SOC The absolute correction point is close to the real SOC. The setting of the absolute correction point for discharge should be determined according to the cell voltage-SOC characteristics. For lithium iron phosphate batteries, due to the plateau period, it is recommended to select SOC below 30%, and 1 to 3 correction points can be set , for ternary lithium batteries, since there is no plateau period, the absolute correction point of the discharge process can be set in the entire SOC segment.

When charging, you can set one or more absolute SOC correction points during the charging process. Through this SOC point, you can get a two-dimensional table of the cell voltage corresponding to each temperature point at multiple charging rates. If it is less than or equal to the discharge rate, the The collected cell voltage is greater than the voltage corresponding to the above-mentioned two-dimensional table according to the temperature, and lasts for several seconds, the absolute correction condition of the charging process is satisfied, that is, the set SOC absolute correction point is similar to the real SOC. For the setting of the charging absolute correction point, it is necessary to According to the cell voltage-SOC characteristics, for lithium iron phosphate batteries, because there is a plateau period, it is recommended to select more than 90%. For ternary lithium batteries, because there is no plateau period, the charging absolute correction point can be set in the entire SOC segment.

S04: If the discharge process correction conditions are not met or the charging process correction conditions are not met, judge whether the minimum cell voltage is less than the reference voltage value at the corresponding temperature point, and if so, enter the discharge end SOC self-learning;

S05: Determine whether the highest cell voltage is greater than the reference value of the voltage at the corresponding temperature point, and if so, enter the charging end SOC self-learning;

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

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

S08: If the judgment result of S07 is true, the initial display SOC is equal to the OCV look-up table SOC value; if the judgment result of S07 is false, the initial display SOC is equal to the stored display SOC value;

S09: carry out the continuous ampere-hour integral calculation with the correction value k based on the initially displayed SOC;

S10: Determine whether the minimum cell voltage is less than the reference value of the voltage at the corresponding temperature point, if so, enter the end-of-discharge SOC self-learning; if not, determine whether the highest cell voltage is greater than the reference value of the voltage at the corresponding temperature point, and if so, enter the end of the charge SOC self-learning; if not, execute S11;

S11: The output shows the SOC and stores it in the corresponding NVM;

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

S13: 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;

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;

S15: determine whether it is in a non-charging state, and if so, re-enter S13;

S16: Determine whether the remaining correction amount is less than 0.001 (P5) or whether it enters the end-of-charge SOC self-learning state or whether it enters the discharge-end SOC self-learning state, if so, the correction rate is equal to 1;

S17: Judging whether the displayed SOC is greater than the absolute correction point of the discharge process and whether the minimum cell voltage is less than or equal to the cell voltage value corresponding to the correction point in the table look-up correction point at each temperature discharge rate and whether it is in a non-charging state, if the judgment result is false, enter the wait The correction condition of the discharge process is satisfied, and the correction rate is equal to 1;

S18: If the waiting time of S17 is greater than the threshold value T3, enter the discharge process SOC acceleration correction, and the correction rate k is greater than 1;

S19: determine whether it is in the charging state, if so, enter the charging process to decelerate and correct, and the correction rate is less than 1;

S20: Determine whether it is in a non-charging state, and if so, enter the SOC acceleration correction in the discharging process;

S21: Determine whether the remaining correction amount is less than 0.001 (P6) or whether it enters the end-of-charge SOC self-learning state or whether it enters the discharge-end SOC self-learning state, if the judgment result is true, the correction rate is equal to 1;

S22: judging whether the displayed SOC is less than the absolute correction point SOC of the charging process and whether the maximum cell voltage is greater than or equal to the cell voltage value corresponding to the correction point in the table look-up correction point under each temperature discharge rate, and whether the charging rate meets the conditions and is in a charging state;

S23: If the judgment result of S22 is true, wait for the charging process correction condition to be satisfied, 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 uncorrected state is entered;

S25: If the waiting time in S23 is greater than the threshold value T3, perform SOC acceleration correction during the charging process, and the correction rate k is greater than 1;

S26: If it is in a non-charging state, perform SOC deceleration correction during the discharge process, and the correction rate k is less than 1;

S27: If the remaining correction amount is less than 0.001 (P4) or enters the end-of-charge SOC self-learning state or enters the discharge-end SOC self-learning state, the correction rate k is equal to 1.

specifically,

In 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, and Cap _toatl is the nominal total capacity of the battery.

specifically,

In S09, the ampere-hour integral calculation is performed 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, and k is the SOC correction rate. If k is equal to 1, the ampere-hour integral is not corrected; If k is greater than 1, charging is deceleration correction, and discharging is acceleration correction; if k is less than 1, charging is acceleration correction, and discharge is deceleration correction.

specifically,

In S03, if the charging process correction condition is satisfied, the SOC acceleration correction in the discharging process in S18 is performed, and the correction rate k is greater than 1;

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

specifically,

In S04, the voltage reference value corresponding to the temperature point is obtained by linearly interpolating the temperature, the discharge rate, and the cell voltage MAP corresponding to the low SOC point, where the SOC is 3%, and each temperature point corresponds to the discharge rate of 0.1C, 0.2C, and 0.33C. The SOC is 3% of the cell voltage, which constitutes the linear interpolation MAP of the voltage reference value at the corresponding temperature point.

specifically,

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

specifically,

In S04, if not, then directly execute S05;

In S05, if not, execute S06 directly.

specifically,

In S03, it is judged whether the charging process correction condition is satisfied, and if so, the initial real SOC is updated to be 90%; it is judged whether the discharge process correction condition is satisfied, and if so, the initial real SOC is updated to be 30%;

In S01, the threshold T1 is 2h;

In S07, the threshold value T2 is 2h;

In S18, the threshold value T3 is 10s.

The present invention also provides an SOC calculation device for a power battery, comprising:

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 look-up table SOC value; if not, the initial real SOC is equal to the stored real SOC value;

a first calculation module for performing continuous ampere-hour integral calculation based on the initial real SOC;

The second judging module is used to continuously judge whether the power battery is in the state of charge. If so, judge whether the charging process correction condition is met. If so, update the initial real SOC to the absolute correction value of the SOC discharge process, clear the ampere-hour integral value, and re- Execute the first calculation module; if not, judge whether the discharge process correction condition is met, and if so, update the initial real SOC to be the absolute correction value of the SOC discharge process, and clear the ampere-hour integral value, and re-execute the second judgment module;

The third judging module is used for judging whether the minimum cell voltage is less than the reference value of the voltage at the corresponding temperature point if the discharge process correction condition is not satisfied or the charging process correction condition is not satisfied, and if so, enter the discharge end SOC self-learning;

The fourth judgment module is used to judge whether the highest cell voltage is greater than the reference value of the voltage at the corresponding temperature point, and if so, enter the charging end SOC self-learning;

The first output module is used to output the real SOC and store it in the corresponding NVM;

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

The seventh judgment module is used to judge whether the minimum cell voltage is less than the reference value of the voltage at the corresponding temperature point. If so, enter the self-learning of the SOC at the discharge end; if not, judge whether the highest cell voltage is greater than the reference value of the voltage at the corresponding temperature point. , then enter the charging end SOC self-learning; if not, execute the second output module;

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

The 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 0.001 (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, 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;

The tenth judging module is used to judge whether it is in a non-charging state, and if so, re-enter the eighth judging module;

The eleventh judgment module is used to judge whether the remaining correction amount is less than 0.001 (P5) or whether it enters the SOC self-learning state at the end of charging or whether it enters the self-learning state of the SOC at the end of discharge. If so, 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 cell voltage is less than or equal to the cell voltage value corresponding to the correction point under the discharge rate of each temperature and whether it is in a non-charging state. If it is false, it will enter and wait for the correction condition of the discharge process to be satisfied, and the correction rate is equal to 1;

The 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 value T3, and the correction rate k is greater than 1;

The fourteenth judging module is used to judge whether it is in the charging state, if so, enter the charging process to decelerate and correct, and the correction rate is less than 1;

The fifteenth judging module is used to judge whether it is in a non-charging state, and if so, enter the SOC acceleration correction in the discharging process;

The sixteenth judgment module is used to judge whether the remaining correction amount is less than 0.001 (P6) or whether it enters the SOC self-learning state at the charging end or whether it enters the SOC self-learning state at the discharging end. If the judgment result is true, the correction rate is equal to 1;

The seventeenth judging 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 cell voltage is greater than or equal to the cell voltage value corresponding to the correction point under each temperature discharge rate and whether the charging rate meets the conditions and is in the Charging state; if the judgment result of S22 is true, wait for the charging process correction condition to be satisfied, 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 the uncorrected state is entered;

An eighteenth judging module, configured to perform a charging process SOC acceleration correction if the waiting time in the seventeenth judging module is greater than the threshold value T3, and the correction rate k is greater than 1;

The nineteenth judging module, if it is in a non-charging state, performs SOC deceleration correction during the discharge process, and the correction rate k is less than 1;

The twentieth judging module is used for the correction rate k equal to 1 if the remaining correction amount is less than 0.001 (P4) or enters the end-of-charge SOC self-learning state or enters the end-of-discharge SOC self-learning state.

specifically,

In the first calculation module, 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, and Cap _toatl is the nominal total capacity of the battery.

specifically,

In the second calculation module, the ampere-hour integral calculation is performed 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, and k is the SOC correction rate. If k is equal to 1, the ampere-hour integral is not corrected; If k is greater than 1, charging is deceleration correction, and discharging is acceleration correction; if k is less than 1, charging is acceleration correction, and discharge is deceleration correction.

specifically,

In the second judgment module, if the charging process correction condition is satisfied, the SOC acceleration correction in the discharging process in S18 is performed, and the correction rate k is greater than 1;

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

specifically,

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

specifically,

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

specifically,

In the third judgment module, if not, then directly execute the fourth judgment module;

In the fourth judging module, if no, the fifth judging module is directly executed.

specifically,

In the second judging module, it is judged whether the charging process correction condition is met, and if so, the initial real SOC is updated to be 90%; it is judged whether the discharge process correction condition is met, and if so, the initial real SOC is updated to 30% .

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

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

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

The present invention also provides an electric vehicle, including the above-mentioned SOC calculation device of the power battery.

Claims (12)

1. The SOC calculation method of the power battery is characterized by comprising three parts of real SOC calculation, SOC calculation display and SOC correction state management; the real SOC calculation is used for representing the current remaining real electric quantity of the power battery, and is used as one of conditions for selecting and displaying the SOC correction rate k through the deviation of the real SOC calculation and the displayed SOC, and once the real SOC value meets the correction condition, the real SOC value directly jumps to the SOC correction target value; the SOC calculation display is used for displaying the current residual electric quantity of the power battery by an instrument and calculating the residual endurance mileage by the vehicle control unit, and the SOC value is displayed to be smooth in change and free of correction mutation in the charging and discharging process; the SOC correction state management is to comprehensively judge to enter each correction state according to the real SOC, the display SOC, the cell voltage and the charging state.

2. The method of calculating the SOC of a power battery according to claim 1, wherein the true SOC calculation includes the steps of:

s01: judging whether the rest time of the BMS after sleeping is greater than a threshold value T1, if so, taking the initial real SOC equal to the OCV table lookup SOC value; if not, the initial real SOC value is taken to be equal to the stored real SOC value;

s02: performing a continuous ampere-hour integral calculation based on the initial true SOC;

s03: continuously judging whether the power battery is in a charging state, if so, judging whether a charging process correction condition is met, if so, updating the initial real SOC to be an SOC charging process absolute correction value, clearing the ampere-hour integral value, and executing the step S02 again; if not, judging whether the discharge process correction condition is met, if so, updating the initial real SOC to be an SOC discharge process absolute correction value, clearing away the ampere-hour integral value, and executing the step S02 again;

s04: continuously judging whether the minimum monomer voltage is smaller than the voltage reference value of the corresponding temperature point, if so, entering self-learning of the SOC at the discharging tail end;

s05: judging whether the highest single voltage is greater than a voltage reference value of a corresponding temperature point, if so, entering SOC self-learning of a charging tail end;

s06: and outputting the real SOC and storing the SOC into the corresponding NVM.

3. The method of calculating the SOC of a power battery according to claim 1, wherein the displaying the SOC calculation includes the steps of:

s07: judging whether the rest time of the BMS after sleeping is greater than a threshold T2 and whether the static OCV table lookup SOC is less than P1 and whether the result of subtracting the static OCV table lookup SOC from the stored display SOC is greater than P2;

s08: if the judgment result of the S07 is true, the initial display SOC is equal to the OCV table lookup SOC value; if the determination result of S07 is false, the initial display SOC is equal to a stored display SOC value;

s09: performing continuous ampere-hour integral calculation with a correction value k based on the initial display SOC;

s10: judging whether the minimum monomer voltage is smaller than the voltage reference value of the corresponding temperature point, if so, entering self-learning of the SOC at the discharging tail end; if not, judging whether the highest monomer voltage is greater than the voltage reference value of the corresponding temperature point, and if so, entering SOC self-learning of the charging tail end; if not, go to S11;

s11: and outputting and displaying the SOC, and storing the SOC into the corresponding NVM.

4. The SOC calculation method for a power battery according to claim 1, wherein the SOC correction state management includes the steps of:

s12: judging whether the SOC is in a non-charging state or not and whether the deviation of the real SOC and the display SOC is larger than P3 or not;

s13: determining whether to enter discharging OCV acceleration correction or discharging OCV deceleration correction according to the deviation of the display SOC and the real SOC; when the deviation is larger than zero, entering acceleration correction; when the deviation is less than zero, entering deceleration correction;

s14: judging whether the charging state is a charging state, if so, entering a charging OCV correction state, and entering charging deceleration correction when the deviation is greater than zero; when the deviation is less than zero, entering SOC charge acceleration correction;

s15: judging whether the charging state is a non-charging state, and if so, re-entering the S13;

s16: judging whether the residual correction amount is smaller than P5 or whether the SOC self-learning state of the charging end or the SOC self-learning state of the discharging end is entered, if so, the correction rate is equal to 1;

s17, judging whether the display SOC is larger than the absolute correction point of the discharging process and the minimum voltage of the monomer is smaller than or equal to the monomer voltage value corresponding to the table lookup correction point under each temperature discharging multiplying power and whether the display SOC is in a non-charging state, if the judgment result is false, entering the waiting discharging process and meeting the correction condition, wherein the correction rate is equal to 1;

s18: if the waiting time of S17 is greater than the threshold value T3, entering the discharging process SOC acceleration correction, wherein the correction rate k is greater than 1;

s19: judging whether the charging state is the charging state, if so, entering a charging process for deceleration correction, wherein the correction rate is less than 1;

s20: judging whether the battery is in a non-charging state, if so, entering a discharging process to accelerate and correct the SOC;

s21: judging whether the residual correction amount is less than P6 or whether the SOC self-learning state of the charging end or the SOC self-learning state of the discharging end is entered, and if the judgment result is true, the correction rate is equal to 1;

s22: judging whether the display SOC is smaller than an absolute correction point SOC in the charging process, whether the maximum voltage of the single body is larger than or equal to a single body voltage value corresponding to the table lookup correction point under each temperature discharge rate, and whether the charging rate meets the condition and is in a charging state;

s23: if the judgment result of the S22 is true, waiting for the charging process correction condition to be met, wherein the correction rate k is equal to 1;

s24: if the judgment result of the S22 is false, the correction rate is equal to 1, and the state is not corrected;

s25: if the waiting time in the step S23 is greater than a threshold value T3, performing SOC acceleration correction in the charging process, wherein the correction rate k is greater than 1;

s26: if the state is a non-charging state, performing SOC deceleration correction in the discharging process, wherein the correction rate k is less than 1;

s27: if the remaining correction amount is less than P4 or enters the end of charge SOC self-learning state or enters the end of discharge SOC self-learning state, the correction rate k is equal to 1.

5. The SOC calculation method for a power battery according to claim 2,

in S02, an ampere-hour integral calculation is performed according to the following formula:

wherein, SOCReal_tFor the current true SOC, I is the bus current of the power battery, Kt is the charge-discharge efficiency, Cap_toatlIs the nominal total capacity of the battery.

6. The SOC calculation method for a power battery according to claim 3,

in S09, an ampere-hour integral calculation is performed according to the following formula:

wherein, SOCDisplay_tFor the current display of SOC, I is the bus current of the power battery, Kt is the charge-discharge efficiency, Cap_toatlThe nominal total capacity of the battery is taken, k is the SOC correction rate, and if k is equal to 1, the ampere-hour integral is not corrected; if k is larger than 1, charging is deceleration correction, and discharging is acceleration correction; if k is less than 1, charging is acceleration correction and discharging is deceleration correction.

7. The SOC calculation method for a power battery according to claim 2,

in the S03, if a discharge process correction condition is satisfied, performing discharge process SOC acceleration correction in the S18, where a correction rate k is greater than 1;

in the S03, if a charging process correction condition is satisfied, the charging process SOC acceleration correction in the S25 is performed, and a correction rate k is greater than 1;

in S04, the corresponding temperature point voltage reference value is obtained by linearly interpolating the cell voltage MAP corresponding to the temperature, the discharge rate, and the low SOC point, where SOC is 3%, and each temperature point discharges the cell voltage corresponding to SOC of 3% at 0.1C, 0.2C, and 0.33C rates, to form the corresponding temperature point voltage reference value linear interpolation MAP.

In S05, the corresponding temperature point voltage reference value is obtained by linearly interpolating the cell voltage MAP corresponding to the temperature, the charge rate, and the high SOC point, where the SOC is 97%, and the cell voltage corresponding to the SOC is 97% charged at each temperature point according to the rates of 0.1c, 0.2c, 0.33c, 0.5c, 0.8c, and 1c, to form the corresponding temperature point voltage reference value linear interpolation MAP.

In the S04, if not, directly execute S05;

in the S05, if not, S06 is directly performed.

In S03, determining whether a charging process correction condition is satisfied, and if so, updating the initial true SOC to 90%; and judging whether the discharge process correction condition is met, if so, updating the initial real SOC to be 30%.

8. An SOC calculation device for a power battery, comprising: the system comprises a real SOC calculation module, a display SOC calculation module and an SOC correction state management module;

the real SOC calculation module is used for representing the current remaining real electric quantity of the power battery, and the deviation between the current remaining real electric quantity of the power battery and the displayed SOC is used as one of the conditions for selecting and displaying the SOC correction rate k, and once the real SOC value meets the correction condition, the real SOC value directly jumps to the SOC correction target value;

the SOC display calculation module is used for displaying the current residual electric quantity of the power battery by an instrument and calculating the residual endurance mileage by the vehicle control unit, and displaying that the SOC value changes smoothly without modification and mutation in the charging and discharging process;

the SOC correction state management module is used for comprehensively judging to enter each correction state according to the real SOC, the display SOC, the cell voltage and the charging state.

9. The power battery SOC calculation device according to claim 8, wherein the true SOC calculation module includes:

the first judgment module is used for judging whether the rest time of the BMS after dormancy is greater than a threshold value T1 or not, and if so, the initial real SOC is equal to an OCV table lookup SOC value; if not, the initial real SOC is equal to the stored real SOC value;

the first calculation module is used for performing continuous ampere-hour integral calculation based on the initial real SOC;

the second judgment module is used for continuously judging whether the power battery is in a charging state, if so, judging whether a charging process correction condition is met, if so, updating the initial real SOC to be an SOC discharging process absolute correction value, clearing an ampere-hour integral value, and executing the first calculation module again; if not, judging whether a discharge process correction condition is met, if so, updating the initial real SOC to be an SOC discharge process absolute correction value, clearing the ampere-hour integral value, and executing the second judgment module again;

the third judgment module is used for judging whether the minimum cell voltage is smaller than the voltage reference value of the corresponding temperature point or not if the discharge process correction condition is not met or the charging process correction condition is not met, and entering self-learning of the SOC at the discharge end if the minimum cell voltage is smaller than the voltage reference value of the corresponding temperature point;

the fourth judging module is used for judging whether the highest monomer voltage is greater than the voltage reference value of the corresponding temperature point or not, and if so, entering SOC self-learning of the charging tail end;

and the first output module is used for outputting the real SOC and storing the real SOC into the corresponding NVM.

10. The power battery SOC calculation device according to claim 8, wherein the display SOC calculation module includes:

the fifth judging module is used for judging whether the rest time of the BMS after the BMS is in the sleep state is greater than a threshold value T2 and whether the static OCV table lookup SOC is less than P1 and whether the result obtained by subtracting the static OCV table lookup SOC from the stored display SOC is greater than P2; if the judgment result of the S07 is true, the initial display SOC is equal to the OCV table lookup SOC value; if the determination result of S07 is false, the initial display SOC is equal to a stored display SOC value;

the second calculation module is used for performing continuous ampere-hour integral calculation with a correction value k based on the initial display SOC;

the seventh judging module is used for judging whether the minimum cell voltage is smaller than the voltage reference value of the corresponding temperature point or not, and if so, entering self-learning of the SOC at the discharging tail end; if not, judging whether the highest monomer voltage is greater than the voltage reference value of the corresponding temperature point, and if so, entering SOC self-learning of the charging tail end; if not, executing a second output module;

and the second output module is used for outputting and displaying the SOC and storing the SOC into the corresponding NVM.

11. The SOC calculation apparatus for a power battery according to claim 8, wherein the SOC correction state management module includes:

an eighth judging module, configured to judge whether the SOC is in a non-charging state and whether a deviation between the actual SOC and the display SOC is greater than P3; determining whether to enter discharging OCV acceleration correction or discharging OCV deceleration correction according to the deviation of the display SOC and the real SOC; when the deviation is larger than zero, entering acceleration correction; when the deviation is less than zero, entering deceleration correction;

the ninth judging module is used for judging whether the charging state is the charging state or not, if so, entering a charging OCV correction state, and entering charging deceleration correction when the deviation is greater than zero; when the deviation is less than zero, entering SOC charge acceleration correction;

a tenth judging module, configured to judge whether the battery is in a non-charging state, and if so, re-enter the eighth judging module;

an eleventh judging module, configured to judge whether the remaining correction amount is less than P5, or whether the remaining correction amount enters a charging end SOC self-learning state, or whether the remaining correction amount enters a discharging end SOC self-learning state, and if yes, the correction rate is equal to 1;

a twelfth judging module, configured to judge whether the display SOC is greater than an absolute correction point in the discharging process and whether the minimum voltage of the cell is less than or equal to a cell voltage value corresponding to the table lookup correction point at each temperature discharging magnification and is in a non-charging state, if the judgment result is false, entering a waiting discharging process, where the correction condition is satisfied and the correction rate is equal to 1;

a thirteenth judging module, configured to enter a discharging process SOC acceleration correction if the waiting time of the twelfth module is greater than a threshold T3, where a correction rate k is greater than 1;

a fourteenth judging module, configured to judge whether the charging status is the charging status, and if so, enter a charging process for deceleration correction, where a correction rate is less than 1;

a fifteenth judging module, configured to judge whether the battery is in a non-charging state, and if so, enter a discharging process SOC acceleration correction;

a sixteenth judging module, configured to judge whether the remaining correction amount is less than P6, or whether the SOC enters a charging end SOC self-learning state, or whether the SOC enters a discharging end SOC self-learning state, where if the judgment result is true, the correction rate is equal to 1;

a seventeenth judging module, configured to judge whether the display SOC is smaller than an absolute correction point SOC in the charging process, whether the maximum voltage of the cell is greater than or equal to a cell voltage value corresponding to the table lookup correction point at each temperature discharge rate, and whether the charging rate satisfies a condition and is in a charging state; if the judgment result of the S22 is true, waiting for the charging process correction condition to be met, wherein the correction rate k is equal to 1; if the judgment result of the S22 is false, the correction rate is equal to 1, and the state is not corrected;

an eighteenth judging module, configured to, if the waiting time in the seventeenth judging module is greater than a threshold T3, perform SOC acceleration correction during the charging process, where a correction rate k is greater than 1;

a nineteenth judging module, if the state is a non-charging state, performing SOC deceleration correction in the discharging process, wherein the correction rate k is less than 1;

and the twentieth judgment module is used for judging whether the residual correction amount is less than P4 or enters a charging end SOC self-learning state or a discharging end SOC self-learning state, and the correction rate k is equal to 1.

12. An electric vehicle characterized by comprising the SOC calculation device of the power battery according to any one of claims 8 to 11.

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