基于Buck-Boost的电池组分时域闭环均衡策略

Buck-Boost-based Closed Loop Equilibrium Strategy for Battery Pack in Time Domain

针对串联锂电池组常规主动均衡控制策略中精度差和速度慢的问题,提出一种基于Buck-Boost的电池组分时域闭环均衡控制策略。硬件上,在均衡拓扑中增加均衡电流采样电路;算法上,在分时域控制策略中加入均衡环路比例积分(PI)控制器调节均衡电流,既可避免电感磁滞饱和又能提升均衡速度。实时检测均衡电流,把均衡转移的能量计入荷电状态(SOC)估计中,以SOC为均衡变量,依次进行相邻电池组间均衡,可提高均衡控制的精度。搭建实验平台,对4节串联锂电池在充电、放电、静置3种条件下进行均衡实验,各单体电池能快速达到平衡且SOC差值在2%以内,实验结果表明所提方法的有效性。

A control strategy for time domain partition of closed loop equilibrium for battery pack based on Buck-Boost is proposed to address the issues of poor accuracy and slow speed in conventional active balancing control strategies for series connected lithium battery pack.In terms of hardware,a balancing current sampling circuit is added to the balancing topology.In terms of algorithm,the balancing loop proportional integral(PI)controller is added to the time domain partition control method to adjust the balancing current,which can not only avoid the hysteresis saturation of the inductor but also improve the equalization speed.The accuracy of balancing control can be improved by detecting the balancing current in real time,including energy transferred by the balancing into the state of charge(SOC)estimation,and using the SOC as the equalization variable,and sequentially balancing between adjacent battery packs.An experimental platform is set up to carry out balancing experiments on four series lithium batteries under three conditions:charging,discharging and standing,and each single battery can quickly reach equilibrium and the SOC difference is within 2%,and the experimental results show the effectiveness of the proposed method.