锂电池组的两级均衡充放电控制策略

Two-stage Equalization Charge-discharge Control Strategy for Lithium-ion Battery Pack

针对电动车辆锂电池组中单体电池数量较多,导致控制复杂且各单体电池充放电不一致等问题,根据电源双向主动均衡理论,提出了一种基于一级对称多绕组变压器和二级直流-直流变换器的两级均衡拓扑及控制策略。运用极差法,分别以电池模组之间电压一致和模组内单体电池电压一致为控制目标,对电池模组和组内单体电池进行能量均衡分配。建模分析表明:本文所提出的均衡系统在充放电期间,使电池模组之间电压和模组内单体电池电压离散度均保持在2%以内,均衡时间为0.5 ms,相较于直流-直流变换器,均衡时间缩短了33.3%。

Owing to the problems of complex control and inconsistent charge caused by a mass of cells of electric vehicle lithium-ion battery pack,a two-stage equalization topology and control strategy were proposed based on first level symmetric multiwinding transformer and second level direct current-direct current(DC-DC)converter with power bidirectional active equalization theory.The energy of lithium-ion battery modules and cells inside module was distributed averagely,in order to realize the objective of consistent lithium-ion battery modules voltage and cells voltage by using the Range method.Modeling analysis demonstrates that the voltage dispersion of lithium-ion battery modules and cells inside module can be kept within 2% during charging and discharging,according to the proposed two-stage lithium-ion battery equalization system.Equalization time is0.5 ms,which is decreased by 33.3% compared with DC-DC converter.