基于模糊控制的锂电池组分层均衡研究

Research on Layer Equalization of Lithium Battery PackBased on Fuzzy Control

传统的电感式均衡电路中要实现电池组均衡,能量只能通过相邻电池慢慢传递而不能在任意电池间转移。这种均衡方式效率低,均衡路径、时间长。为此,提出一种Buck-Boost电路与反激式电路相结合的新型分层拓扑。组内均衡采用双向Buck-Boost电路,使能量仅在相邻两节电池之间转移,因而均衡路径短。组间均衡采用双向反激式电路,通过控制原副边绕组开关管状态,使能量在模组与电池组间相互转移,从而达到电池组均衡。在均衡过程中加入模糊控制策略,动态调节开关管的占空比,以输出合适的均衡电流、提高均衡效率。搭建Matlab仿真模型进行分析。仿真结果表明,所提出的均衡电路相较于传统的Buck-Boost电路在静置和充、放电状态下均衡时间分别缩短约18%、17%和20%。均衡效率的提高对未来电动汽车等多锂电池串联设备的发展有着重要意义。

To realize battery pack equalization in traditional inductive equalization circuits,energy can only be transferred slowly through adjacent cells but not between any cells.This equalization method is inefficient,and the equalization path and time are long.For this reason,a new hierarchical topology combining Buck-Boost circuit and flyback circuit is proposed.The intra-group equalization uses a bidirectional Buck-Boost circuit,so that the energy is transferred only between two neighboring batteries and the equalization path is short.The inter-group equalization adopts a bidirectional flyback circuit,which controls the switching tubes state of the primary and secondary side windings to transfer energy between the module and the battery packs,to achieve battery pack equalization.A fuzzy control strategy is added in the equalization process to dynamically adjust the duty cycle of the switching tubes to output a suitable equalization current and improve the equalization efficiency.A Matlab simulation model is built for analysis.The simulation results show that the proposed equalization circuit reduces the equalization time by about 18%,22%,and 20% compared with the traditional Buck-Boost circuit in the static,charging,and discharging states,respectively.The improvement of equalization efficiency is of great significance for the future development of multi-lithium battery series connection devices such as electric vehicles.