锂离子电池组均衡控制策略研究

Research on balance control strategy of lithium-ion battery pack

由于电池电压非常容易获得,故以电池电压为指标的均衡控制策略被广泛应用,但该策略很难让电池管理系统(battery management system,BMS)较好地实现电池均衡的目标。提出一种新的均衡控制策略,该策略以电池组中任意两节电池荷电状态(state of charge,SOC)之差作为指标,进而对电池组进行均衡。简单地说,由于电池组SOC与其开路电压(open circuit voltage,OCV)存在一定的关系,利用该关系,可以将电池单体电压之差转换为电池SOC之差,进而为BMS提供较优的均衡指标。该策略与电压均衡控制策略一样简单,并且在性能上要优于电压均衡控制策略。搭建7节电池串联组成的实验平台进行验证,使电池组中最大与最小电池电压之差为65 mV,相较于电压均衡控制策略将该电压之差缩小至45 mV,所提出的均衡控制策略,在电池静置状态可以将其缩小至2 mV,在放电状态可以将其缩小至6 mV,证明了该均衡控制策略的优异性。

Due to the easy obtaining of the cell voltage,the balance control strategy based on the voltage is widely used,but this strategy is difficult for the BMS to better achieve the goal of cell balance.This paper proposed a new balance control strategy,which took the difference between the SOCs of any two battery cells in the battery pack as an indicator to balance the battery pack.In brief,because SOC of the battery pack has a certain relationship with its OCV,using this relationship,the difference in voltages of battery cells can be converted into the difference in SOCs,thereby providing a better index for BMS.This strategy is as simple as the voltage balance control strategy,and is better than the voltage balance control strategy in performance.An experimental platform consisting of 7 battery cells in series was built for verification,and the difference between the maximum and minimum voltages of the battery cells in the battery pack was 65 mV.Compared with the voltage balance control strategy to 45 mV,the balance control strategy proposed in this article reduces to 2 mV in the static state,and to 6 mV in the discharged state,which proves the superiority of the balance control strategy.