基于SOC的动力电池组主动均衡研究

Research on active equalization of power batteries based on state of charge

动力电池单体容量不一致会导致动力电池组在充放电过程中失去平衡,影响动力电池组的使用效果,降低动力电池组的使用寿命。为了解决这一难题,本工作设计了一种基于荷电状态(SOC)值的主动均衡电池管理系统。该电池管理系统利用安时积分法估计动力电池组中各电池单体的SOC值,在此基础上计算动力电池组的SOC平均值,然后将各动力电池单体的SOC值与动力电池组的SOC平均值进行比较,若二者的差值大于或小于设定的阈值,电池管理系统将控制DC/DC变换器和开关电路对相应的电池单体进行充电或放电,实现电池组能量的转移,从而达到均衡的目的。以4块动力电池单体串联而成的动力电池组为例,对该主动均衡电池管理系统的有效性进行了仿真验证。仿真结果表明,经过该系统的主动均衡,3608 s后各动力电池单体之间的SOC差值由初始的7.8%迅速减小到3%以内,5600 s后减小到1%,大大降低了动力电池中各电池单体SOC值的不一致。

The capacity and other parameters of a single power battery are different, which causes imbalance on charging and discharging, poor performance, and reduced service life of series and parallel power batteries. To solve this problem, an active equalization battery management system based on state of charge(SOC) is designed. After estimating the SOC of a single power battery using the ampere-hour integral method, the battery management system will compare the SOC of the single power battery with the average SOC of the power battery. If the difference value is greater than or less than the set threshold, discharging and charging of the single power batteries will be carried out separately. The validity of the battery management system is verified by simulation through taking four single batteries in series.The simulation results show that the SOC difference values of the single power battery are less than 3% after 3608 s and 1% after 5600 s through active equalization, which greatly reduce the SOC inconsistency of the power batteries.