CN107861074B - Lithium battery SOC estimation method - Google Patents
Lithium battery SOC estimation method Download PDFInfo
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- CN107861074B CN107861074B CN201711397185.4A CN201711397185A CN107861074B CN 107861074 B CN107861074 B CN 107861074B CN 201711397185 A CN201711397185 A CN 201711397185A CN 107861074 B CN107861074 B CN 107861074B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
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Abstract
The invention relates to a lithium battery SOC estimation method, which comprises the following steps: roughly estimating a battery SOC value to obtain a SOC rough value; the BMS calculates the actual discharged amount of the battery in real time during the running process of the vehicle; when the SOC rough value is smaller than a pre-calibrated critical value, calculating the theoretical discharged capacity of the battery according to the rated capacity of the battery; according to the rated capacity of the battery, the actual discharged capacity and the theoretical discharged capacity, the BMS calculates the actual rated capacity of the battery and stores the actual rated capacity into the EEPROM for calculating the accurate SOC value of the battery, and the original rated capacity is equal to the actual rated capacity; the accurate SOC value of the battery at that time is calculated based on the actually calculated actual rated capacity. The invention can improve the reliability and stability of the SOC estimation of the battery, record the historical rated capacity value of the battery, reflect the health condition of the battery, effectively solve the problem of inaccurate SOC estimation of the battery caused by aging of the battery or inconsistent quality of the battery core, and well meet the requirements of practical application.
Description
Technical Field
The invention relates to a lithium battery SOC estimation method.
Background
The accurate estimation of the State of Charge (SOC) of the battery is an important basis for the Charge and discharge control and the power optimization management of the battery of the electric automobile, directly influences the service life of the battery and the power performance of the automobile, and can predict the driving range of the electric automobile. It can be seen that accurate measurement of the remaining battery capacity is a very critical issue. The SOC calculation formula of the battery is as follows: SOC is 1-Q/C. The conventional lithium battery SOC estimation method for the new energy automobile comprises an ampere-hour integral method and a Kalman filtering method, and no matter which estimation method is adopted, the SOC of the battery cannot be estimated accurately and reliably no matter how the total capacity C of the battery cannot be accurately calculated and the quantity Q of electricity discharged by the battery cannot be accurately estimated.
In the recycling process of the lithium battery, the service life of the lithium battery is gradually shortened, and meanwhile, the rated capacity of the lithium battery is gradually reduced, so that if a traditional SOC estimation method is adopted, the rated capacity of the lithium battery is always taken as a fixed value when the lithium battery leaves a factory, and the SOC estimation of the lithium battery is inevitably inaccurate. Even if the precision of the discharged amount of the battery is continuously improved, the accuracy of the SOC estimation of the battery cannot be ensured.
The power battery PACK of the new energy automobile is composed of a large number of single battery cells, the consistency of each single battery cell is difficult to ensure during assembly, and the actual capacity of some single battery cells is possibly smaller. If the battery SOC is also estimated according to the rated capacity, the final SOC estimation must not be accurate.
In the process of recycling the power battery PACK, due to differences of the monomer battery cells, some monomer battery cells cannot be completely filled during charging. For the single battery cells which are not fully charged, the estimation of the battery SOC is carried out according to the rated capacity, so that the finally estimated battery SOC is not accurate.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a method for estimating SOC of a lithium battery, which can avoid the above technical drawbacks.
In order to achieve the above object, the present invention provides the following technical solutions:
a lithium battery SOC estimation method comprises the following steps:
the method comprises the following steps: roughly estimating the SOC value of the battery to obtain the SOC rough value SOCCoarse；
Step two: for SOCCoarseCorrecting to obtain the accurate SOC valuePrecision of。
Further, the first step comprises the following steps:
step 1) when the battery PACK leaves factory, all monomer battery cores of the battery PACK are fully charged, and the BMS calculates the current capacity of the battery PACK and takes the current capacity as the rated capacity C of the batteryRated valueThen the calculated rated capacity C of the batteryRated valueStored in EEPROM as rated capacity C of battery deliveryRated value；
Step 2) according to the rated capacity C of the batteryRated valueEstimating a coarse battery SOC value SOCCoarse。
Further, the step 2) is specifically as follows: by using KaerMandarin filter method or ampere-hour integration method according to rated capacity C of batteryRated valueEstimating a coarse battery SOC value SOCCoarse。
Further, the second step comprises the following steps:
step (1) in the running process of the vehicle, the BMS calculates the actual discharged quantity Q of the battery in real timePractical placing；
Step (2) when the battery SOCCoarseSOC less than a pre-calibrated thresholdCritical valueAccording to the rated capacity C of the batteryRated valueCalculating to obtain the theoretical discharged quantity Q of the batteryTheory of the invention：
QTheory of the invention＝CRated value·(1-SOCCritical value)；
Step (3) according to the rated capacity C of the batteryRated valueActual discharged amount QPractical placingAnd theoretical discharged quantity QTheory of the inventionBMS calculates the actual rated capacity C of the batteryActual ratingAnd storing the data into EEPROM for calculating the accurate SOC value of the batteryPrecision ofUsed and original rated capacity CRated valueEqual to the actual rated capacity CActual rating：
CActual rating＝CRated value·QPractical placing/QTheory of the invention；
Step (4) according to the actual rated capacity C calculated actuallyActual ratingTo calculate the accurate SOC value SOC of the battery at the timePrecision of：SOCPrecision of＝1–QPractical placing/CActual rating。
Further, in the step (1), the BMS calculates the actual discharged capacity Q of the battery in real time by adopting a Kalman filtering method or an ampere-hour integration methodPractical placing。
The method for estimating the SOC of the lithium battery can improve the reliability and stability of the SOC estimation of the battery, obtain an accurate SOC value, record a historical rated capacity value of the battery, reflect the health condition of the battery, effectively solve the problem of inaccurate SOC estimation of the battery caused by battery aging or inconsistent quality of a battery core, and realize the purpose of estimating the critical value SOC by a calibration methodCritical valueCan well meet the requirements of practical application.
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FIG. 1 is a flow chart of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A lithium battery SOC estimation method comprises the following steps:
the method comprises the following steps: roughly estimating the SOC value of the battery to obtain the SOC rough value SOCCoarse；
Step two: for SOCCoarseCorrecting to obtain the accurate SOC valuePrecision of。
Specifically, as shown in fig. 1:
the first step comprises the following steps:
step 1) when the battery PACK leaves the factory, all the monomer battery cores of the battery PACK are fully charged, and the BMS (Battery management System) calculates the capacity of the battery PACK at the moment and takes the capacity as the rated capacity C of the batteryRated valueThen the calculated rated capacity C of the batteryRated valueStored in EEPROM as rated capacity C of battery deliveryRated value；
Step 2) adopting a traditional SOC estimation method such as a Kalman filtering method or an ampere-hour integration method according to the rated capacity C of the batteryRated valueEstimating a coarse battery SOC value SOCCoarse。
The second step comprises the following steps:
step (1) in the running process of the vehicle, the BMS calculates the actual discharged capacity Q of the battery in real time by adopting a Kalman filtering method or an ampere-hour integration methodPractical placing；
Step (2) when the battery SOCCoarseSOC less than a pre-calibrated thresholdCritical valueAccording to the rated capacity C of the batteryRated valueCalculating to obtain the theoretical discharged quantity Q of the batteryTheory of the invention：
QTheory of the invention＝CRated value·(1-SOCCritical value)；
Step (3) according to the rated capacity C of the batteryRated valueActual discharged amount QPractical placingAnd theoretical discharged quantity QTheory of the inventionBMS calculates the actual rated capacity C of the batteryActual ratingAnd storing the data into EEPROM for calculating the accurate SOC value of the batteryPrecision ofUsed and original rated capacity CRated valueEqual to the actual rated capacity CActual rating：
CActual rating＝CRated value·QPractical placing/QTheory of the invention；
CRated value＝CActual rating；
Step (4) according to the actual rated capacity C calculated actuallyActual ratingTo calculate the accurate SOC value SOC of the battery at the timePrecision of，SOCPrecision of＝1–QPractical placing/CActual rating，SOCPrecision ofI.e. the exact SOC value of the battery at that time.
The method for estimating the SOC of the lithium battery can improve the reliability and stability of the SOC estimation of the battery, obtain an accurate SOC value, record a historical rated capacity value of the battery, reflect the health condition of the battery, effectively solve the problem of inaccurate SOC estimation of the battery caused by battery aging or inconsistent quality of a battery core, and realize the purpose of estimating the critical value SOC by a calibration methodCritical valueCan well meet the requirements of practical application.
The above-mentioned embodiments only express the embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (4)
1. A lithium battery SOC estimation method is characterized by comprising the following steps:
the method comprises the following steps: roughly estimating the SOC value of the battery to obtain the SOC rough value SOCCoarse；
Step two: for SOCCoarseCorrecting to obtain the accurate SOC valuePrecision ofThe method comprises the following steps:
step (1) in the running process of the vehicle, the BMS calculates the actual discharged quantity Q of the battery in real timePractical placing；
Step (2) when the battery SOCCoarseSOC less than a pre-calibrated thresholdCritical valueAccording to the rated capacity C of the batteryRated valueCalculating to obtain the theoretical discharged quantity Q of the batteryTheory of the invention：
QTheory of the invention＝CRated value·(1-SOCCritical value)；
Step (3) according to the rated capacity C of the batteryRated valueActual discharged amount QPractical placingAnd theoretical discharged quantity QTheory of the inventionBMS calculates the actual rated capacity C of the batteryActual ratingAnd storing the data into EEPROM for calculating the accurate SOC value of the batteryPrecision ofUsed and original rated capacity CRated valueEqual to the actual rated capacity CActual rating：
CActual rating＝CRated value·QPractical placing/QTheory of the invention；
Step (4) according to the actual rated capacity C calculated actuallyActual ratingTo calculate the accurate SOC value SOC of the battery at the timePrecision of：SOCPrecision of＝1–QPractical placing/CActual rating。
2. The method for estimating the SOC of the lithium battery as claimed in claim 1, wherein the first step includes the steps of:
step 1) when the battery PACK leaves the factory, all the monomer battery cores of the battery PACK are fully charged, and the BMS calculates the capacity of the battery PACK at the moment andusing it as the rated capacity C of the batteryRated valueThen the calculated rated capacity C of the batteryRated valueStored in EEPROM as rated capacity C of battery deliveryRated value；
Step 2) according to the rated capacity C of the batteryRated valueEstimating a coarse battery SOC value SOCCoarse。
3. The method for estimating the SOC of the lithium battery according to claim 2, wherein the step 2) is specifically: adopting a Kalman filtering method or an ampere-hour integration method according to the rated capacity C of the batteryRated valueEstimating a coarse battery SOC value SOCCoarse。
4. The method for estimating the SOC of a lithium battery as claimed in claim 1, wherein in the step (1), the BMS calculates the actual discharged amount Q of the battery in real time using a kalman filter method or an ampere-hour integration methodPractical placing。
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| CN111007412B (en) * | 2019-12-25 | 2022-05-17 | 宜宾凯翼汽车有限公司 | Method for updating actual available capacity of power battery |
| CN111239624B (en) * | 2020-02-21 | 2022-10-11 | 中创新航科技股份有限公司 | Battery capacity calibration method and device, electronic equipment and storage medium |
| CN112415400B (en) * | 2020-10-21 | 2023-09-12 | 欣旺达电动汽车电池有限公司 | Battery capacity estimation method and system |
| CN113075558B (en) * | 2021-06-08 | 2021-08-10 | 天津市松正电动科技有限公司 | Battery SOC estimation method, device and system |
| CN114114056B (en) * | 2022-01-25 | 2022-04-26 | 深圳康普盾科技股份有限公司 | Battery detection and recovery method and system of power exchange cabinet and storage medium |
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