基于可用容量估算和电量增量曲线的安时积分荷电状态估算方法

Ampere Hour Integrated State of Charge Estimation Method Based on Available Capacity Estimation and Power Increment Curve

荷电状态(State of Charge, SOC)估算是电动汽车电池管理系统的重要功能之一,安时积分因其计算简单、不依赖具体电池模型的优点而广泛应用于SOC估算,但电流传感器的累计误差和电池可用容量误差会使SOC估算误差越来越大。从导致安时积分估算误差的原因出发,首先利用最小二乘法对电流传感器进行校准,然后利用温度和可用容量的关系对电池包可用容量进行估算,最后利用电池包充电过程中的电量增量(Incremental Capacity, IC)曲线对估算的SOC进行修正。通过长时间不同温度下连续动态压力测试(Dynamic Stress Test, DST)工况放电-恒流充电的不完全充放电实验,结果表明改进后的安时积分SOC估算误差在充放电过程中不超过4.1%,充电修正后的误差不超过3%,得到了比较精确的估算结果。

State of charge(SOC) estimation is one of the important functions of battery management system for electric vehicles. Ampere-hour integral is widely used in SOC estimation because of its simple calculation and being independent of specific battery model, but the cumulative error of current sensor and battery capacity estimation error will make SOC estimation error more and more large. In this paper, derived from the error of ampere hour integral estimation, the least square method is used to calibrate the current sensor, and then the relationship between the initial temperature and the discharge capacity is used to estimate the battery pack capacity. Finally, the estimated SOC is modified by the incremental capacity(IC) curve of the battery charge process. In this paper, the incomplete constant current charge and discharge under the condition of dynamic stress test(DST) experiments for a long time are carried out. The results show that the improved error of SOC estimation is less than 4.1% during charging and discharging, and the error after charging correction is less than 3%. That is, more accurate estimation results are obtained.