基于Buck-Boost电路的能量转移型均衡方案

提出了一种基于Buck-Boost电路的新型均衡电路,实现了锂离子串联电池组充放电均衡。根据均衡能量流向,采取两种不同的均衡策略:电池组放电时,均衡能量由电池组向组内荷电状态(state of charge,SOC)较低的单体电池转移;电池组充电时,均衡能量由电池组中SOC较高的单体电池向电池组转移。以单体电池开路电压在线估计为基础,运用开路电压法估算SOC,选取SOC值在一定阈值范围之外的单体电池作为均衡对象,对6节串联的磷酸铁锂电池进行了充放电均衡实验。实验结果表明,该方案可以有效减小单体电池间的不一致性,提升电池组的整体性,同时提高了电池组充放电容量。

Energy-transferring equalization scheme based on Boost-Buck circuit

A new equalization circuit based on Boost-Buck circuit was proposed,which realizes the charge and discharge equalization of series-connected lithium-ion batteries.Two different balancing strategies were used respectively according to the balanced energy-transferring direction.When battery pack was discharging,the balanced energy was transferred from the battery pack to the batteries with lower stage of charge (SOC);When battery pack was charging,the balanced energy was transferred from the higher SOC batteries to the battery pack.The scheme were based on online estimation of open circuit voltage (OCV) of single cell,which takes advantage of OCV-SOC curve to estimate the stage of charge (SOC),balanced objects were selected whose SOC are outside a certain range and an experiment was performed for six serially connected LiFeP04 battery cells.Experimental results confirm that the inconsistency between the single cells is validly reduced,the integrity of the battery pack is improved and the charging and discharging of battery pack is increased.