Method for correcting lithium battery SOC according to dynamic voltage

Abstract

The invention provides a method for correcting a lithium battery SOC according to dynamic voltage. The method comprises the following steps of S1, obtaining the corresponding relation between dynamicend voltage and SOC of a battery under different temperatures and different multiplying powers through experiments; S2, according to the characteristics of the battery, selecting calibrated points inthe charging process and the discharging process; S3, in the traveling car discharging process, when it is judged that the continuous setup frequency that the current is smaller than a set threshold value and the voltage is smaller than a threshold value corresponding to the current temperature reaches a set threshold value in real time, if the current SOC is larger than the SOC corresponding to the calibrated point, calibrating the current SOC to the SOC corresponding to the calibrated point; S4, in the charging process, when it is judged that the current is smaller than the set threshold value, and the voltage is smaller than the threshold value corresponding to the current temperature in real time, if the current SOC is smaller than the SOC corresponding to the calibrated point, calibrating the current SOC to the SOC corresponding to the calibrated point. In the traveling car process, algorithm operation is performed in real time, a program does not reply on the special standing working condition, and in the SOC calibration process, it is ensured that SOC smoothness changes cannot change suddenly.

Description

technical field [0001] The invention relates to the field of battery management systems, in particular to a method for correcting the SOC of a lithium battery by using the terminal voltage of the battery during discharge to reduce the SOC error. Background technique [0002] As one of the core components of electric vehicles, the battery management system (Battery Management System, BMS) has always been the focus of electric vehicle research and development. Due to the complex working environment and working conditions of electric vehicles and the complex chemical characteristics of batteries, compared with traditional fuel vehicles, the main technical difficulty of new energy vehicles lies in the accuracy of mileage estimation. SOC is the most important parameter for calculating cruising range, and SOC calculation has become one of the core functions of BMS. The accuracy of SOC calculation directly determines the quality of BMS. [0003] At present, the ampere-hour integra...

AI Technical Summary

Problems solved by technology

However, there are obvious defects in the ampere-hour integration method: 1. The accuracy of the ampere-hour integration algorithm depends on the accuracy of the current sensor, and in the case of a systematic error in the current sensor, the long-term pure ampere-hour integration strategy will inevitably lead to an increase in the error of the SOC. getting bigger

2. Due to the self-discharge phenomenon of lithium batteries, and the ampere-hour integration does not take this into account, the long-term pure ampere-hour integration algorithm will inevitably lead to a falsely high SOC

4. When fully charged, it is directly calibrated to 100% according to the current voltage condition, and the SOC may jump.

But this scheme also has obvious disadvantages: 1. In this method, there are clear requirements on the working conditions of the vehicle, and there must be enough standing time

2. In view of the plateau period of lithium iron phosphate batteries, the voltage change range is very small in the range of 30% to 90%. The voltage acquisition accuracy of the current BMS is generally 5mv, and the OCV calibration scheme will have a huge error

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