Search

EP-3951408-B1 - METHOD AND APPARATUS FOR ACQUIRING STATE OF HEALTH OF BATTERY, AND STORAGE MEDIUM

EP3951408B1EP 3951408 B1EP3951408 B1EP 3951408B1EP-3951408-B1

Inventors

  • YOU, Shiyun
  • LIU, HAIYANG
  • MAO, Jun

Dates

Publication Date
20260506
Application Date
20201210

Claims (7)

  1. A method for acquiring a state of health of a battery, wherein the method is carried out by the device according to claim 4, and wherein the method comprises: when a vehicle is powered on, determining (101) whether a capacity variation calculation condition is satisfied; when determining that the capacity variation calculation condition is satisfied, calculating (102) a capacity variation; when the vehicle is powered on, determining (103) whether a capacity calculation condition is satisfied; when determining that the capacity calculation condition is satisfied, calculating (104) a capacity; and calculating (105) the state of health of the battery according to the capacity variation and the capacity; wherein the capacity variation calculation condition comprises satisfying the following two conditions at the same time: capacity variation calculation condition A: a parking time is greater than or equal to S1; the S1 being a preset parking time threshold of the capacity variation calculation condition; and capacity variation calculation condition B: SOC1≤SOC_judge1; the SOC1 being an SOC value of an OCV-SOC curve of the battery corresponding to a current voltage of a minimum unit voltage; and the SOC_judge1 being a preset state of charge threshold of the capacity variation calculation condition; wherein the step of calculating (204) the capacity variation comprises: calculating: ΔCap = ∫ T 1 RTC − Idt ΔDchaCap = ∫ T 1 RTC I d dt wherein, T1 is a time point when determining that the capacity variation calculation condition is satisfied; RTC is a time to calculate ΔCap or ΔDchaCap, which is capable of being acquired by internal timing of a BMS or acquired externally; I is a current of the battery; I d is a current in a discharge direction of the battery; ΔCap is a capacity variation accumulated from a start time of T1; and ΔDchaCap is a capacity variation in the discharge direction accumulated from the start time of T1; wherein the capacity calculation condition comprises satisfying the following four conditions: capacity calculation condition A: a parking time is greater than or equal to S2; the parking time being a time interval between last power-off and the present power-on; and S2 being a preset time threshold of the capacity calculation condition; capacity calculation condition B: SOC2≤SOC_judge2; the SOC2 being an SOC value of the battery corresponding to a maximum unit voltage in an OCV-SOC curve; and the SOC_judge2 being a preset SOC threshold of the capacity calculation condition; capacity calculation condition C: CT-T1≤T_Judge; wherein the CT is the time point when determining whether the capacity calculation condition is satisfied; T1 is the time point when determining that the capacity variation calculation condition is satisfied; and T_Judge is a preset time difference threshold; and capacity calculation condition D: ΔDchaCap≤ΔDchaCap_Judge; wherein the ΔDchaCap is the capacity variation in the discharge direction accumulated from the start time of T1; and the ΔDchaCap_Judge is a preset upper limit of a capacity variation threshold; wherein the step of calculating (206) the capacity comprises: Cap_cal = Δ Cap SOC 2 − SOC 1 wherein the Cap_cal is an actual capacity of the battery; and the ΔCap is the capacity variation accumulated from the start time of T1, wherein the step of calculating (207) the state of health of the battery according to the capacity variation and the capacity comprises: calculating: SOH_C = Cap _ cal Cap _ rate × 100 % wherein the SOH_C is the state of health of the battery; and the Cap_rate is a nominal capacity of the battery delivered from a factory.
  2. The method for acquiring the state of health of the battery according to claim 1, wherein before the step of determining (101) whether the capacity variation calculation condition is satisfied, the method further comprises: when the vehicle is powered on, determining (201) whether an ongoing capacity variation calculation process exists at present; if the ongoing capacity variation calculation process exists, performing (205) the step of determining whether the capacity calculation condition is satisfied; and if no ongoing capacity variation calculation process exists, performing (203) the step of determining whether the capacity variation calculation condition is satisfied.
  3. The method for acquiring the state of health of the battery according to claim 1, wherein before the step of determining (101) whether the capacity variation calculation condition is satisfied, the method further comprises: when the vehicle is powered on, determining (201) whether an ongoing capacity variation calculation process exists at present; if determining that the ongoing capacity variation calculation process exists, determining (202) whether the ongoing capacity variation calculation process is overdue; if determining that no ongoing capacity variation calculation process exists, performing (203) the step of determining whether the capacity variation calculation condition is satisfied; if determining the ongoing capacity variation calculation process is overdue, performing (203) the step of determining whether the capacity variation calculation condition is satisfied; and if determining the ongoing capacity variation calculation process is not overdue, performing (205) the step of determining whether the capacity calculation condition is satisfied.
  4. A device for acquiring a state of health of a battery, wherein the device comprises: a capacity variation calculation condition determining module (301) configured for, when a vehicle is powered on, determining whether a capacity variation calculation condition is satisfied; a capacity variation calculation module (302) configured for calculating a capacity variation; a capacity calculation condition determining module (303) configured for, when the vehicle is powered on, determining whether a capacity calculation condition is satisfied; a capacity calculation module (304) configured for calculating a capacity; and a calculation module for state of health (305) configured for calculating the state of health of the battery according to the capacity variation and the capacity; wherein the capacity variation calculation condition comprises satisfying the following two conditions at the same time: capacity variation calculation condition A: a parking time is greater than or equal to S1; the S1 being a preset parking time threshold of the capacity variation calculation condition; and capacity variation calculation condition B: SOC1≤SOC_judge1; the SOC1 being an SOC value of an OCV-SOC curve of the battery corresponding to a current voltage of a minimum unit voltage; and the SOC_judge1 being a preset state of charge threshold of the capacity variation calculation condition; wherein the capacity variation calculation module (302) configured for: calculating: ΔCap = ∫ T 1 RTC − Idt ΔDchaCap = ∫ T 1 RTC I d dt wherein T1 is a time point when determining that the capacity variation calculation condition is satisfied; RTC is a time to calculate ΔCap or ΔDchaCap, which is capable of being acquired by internal timing of a BMS or acquired externally; I is a current of the battery; I d is a current in a discharge direction of the battery; ΔCap is a capacity variation accumulated from a start time of T1; and ΔDchaCap is a capacity variation in the discharge direction accumulated from the start time of T1; wherein the capacity calculation condition comprises satisfying the following four conditions: capacity calculation condition A: a parking time is greater than or equal to S2; the parking time being a time interval between last power-off and the present power-on; and S2 being a preset time threshold of the capacity calculation condition; capacity calculation condition B: SOC2≤SOC_judge2; the SOC2 being an SOC value of the battery corresponding to a maximum unit voltage in an OCV-SOC curve; and the SOC_judge2 being a preset SOC threshold of the capacity calculation condition; capacity calculation condition C: CT-T1≤T_Judge; wherein the CT is the time point when determining whether the capacity calculation condition is satisfied; T1 is the time point when determining that the capacity variation calculation condition is satisfied; and T_Judge is a preset time difference threshold; and capacity calculation condition D: ΔDchaCap ≤ΔDchaCap_Judge; wherein the ΔDchaCap is the capacity variation in the discharge direction accumulated from the start time of T1; and the ΔDchaCap_Judge is a preset upper limit of a capacity variation threshold; wherein the capacity calculation module (304) is configured for: Cap_cal = Δ Cap SOC 2 − SOC 1 wherein the Cap_cal is an actual capacity of the battery; and the ΔCap is the capacity variation accumulated from the start time of T1, wherein the calculation module for state of health (305) is configured for: calculating: SOH_C = Cap _ cal Cap _ rate × 100 % wherein the SOH_C is the state of health of the battery; and the Cap_rate is a nominal capacity of the battery delivered from a factory.
  5. A vehicle comprising the device for acquiring the state of health of the battery according to claim 4.
  6. A computer program product comprising instructions to cause the device of claim 4 to execute the method for acquiring the state of health of the battery according to any one of claims 1 to 3.
  7. A computer-readable storage medium comprising the computer program product according to claim 6.

Description

TECHNICAL FIELD The present disclosure relates to the technical field of batteries, and particularly relates to a method and device for acquiring a state of health of a battery, a vehicle, a computer program product and a computer-readable storage medium. BACKGROUND For new energy vehicles, especially pure electric vehicles, lithium-ion power batteries are the main power sources. A state of health (SOH) of the battery is an important parameter of the power battery, which indicates an aging degree of the battery, that is, the attenuation of a capacity and the increase of an internal resistance. The SOH is also related to the estimation of other important states of the battery, such as a state of charge(SOC) and an allowable power, which directly affect a driving range and a driving experience. Therefore, how to accurately estimate the SOH of the battery is an important issue for the pure electric vehicles. Currently, the SOH of the lithium-ion power battery for the new energy vehicle is generally estimated by: firstly measuring a cycle number of the battery, and then obtaining the state of health SOH of the battery by querying a correspondence table between the cycle number measured in advance and the SOH. In fact, due to the different temperatures and working conditions of the battery in different vehicles and differences between the batteries, the SOHs of different batteries are actually different even with the same cycle times, so this method cannot truly reflect the actual SOH of the battery, which leads to inaccurate estimation of the SOC and the driving range, and seriously affects the driving experience of users. US 2015/0346285 A1 discloses a device for assessing an extent of degradation of a secondary battery, including: a determination unit that determines whether or not a value of current flowing in the secondary battery is less than a predetermined value; a first voltage measurement unit that takes a time point at which it is determined by the determination unit that the value of the current is less than the predetermined value as being a start time point of a specific interval, and that measures a first battery voltage of the secondary battery at the start time point; a first charge amount calculation unit that obtains a first charge amount corresponding to the secondary battery based upon the measured first battery voltage; a second voltage measurement unit that, after the first battery voltage has been measured by the first voltage measurement unit, takes a time point at which itis determined by the determination unit that the value of the current is less than the predetermined value as being an end time point of the specific interval, and that measures a second battery voltage of the secondary battery at the end time point; a second charge amount calculation unit that obtains a second charge amount corresponding to the secondary battery based upon the measured second battery voltage; an integrated current amount calculation unit that obtains an integrated amount of the current flowing in the secondary battery during the specific interval; and a charge capacity calculation unit that obtains a difference between the first charge amount and the second charge amount, and that calculates a charge capacity by dividing the integrated amount of the current by the difference. US 2015/0120225 A1 discloses an apparatus and a method for determining degradation of a high-voltage vehicle battery. The apparatus for determining degradation of a high-voltage vehicle battery is configured to measure a battery state of health (SOH) according to a preset estimation calculation, thereby minimizing a battery degradation estimation error. It is possible to calculate a capacity of a battery only using a current value and a state of charge (SOC) change value to estimate an SOH of the battery, thereby simplifying an algorithm for the estimation. In particular, it is also advantageously possible to estimate a battery SOH through a first estimation algorithm, compare the estimated battery SOH with a threshold value, determine whether to perform re-estimation and if the re-estimation is determined, re-estimate the battery SOH through a second estimation algorithm, using a least mean square method, thereby minimizing an error in a battery SOH estimation value. US 2004/0257045 A1 discloses a voltage control apparatus which checks a battery voltage when an automotive generator gradually increases its output to be within a predetermined range after temporarily stopping the generator. Then, the battery voltage is picked up to calculate the charge rate. Further, a first charge rate and a first residual capacity of the battery are memorized when the engine is stopped. Periodically, a pseudo-open circuit voltage is checked when a charge/discharge current fits within a pre-determined small range while the engine is not running, and a second charge rate is calculated based on the checked pseudo-open circuit voltage. A second resid