电动汽车锂电池组的新型双向均衡法

由于电池制造工艺的制约导致生产出的电池间存在一定的离散性,多次充放电后不一致性更加严重,因此有必要对电动汽车电池组进行均衡.在分析了锂电池间不一致性的基础上建立了双向均衡结构,采用粒子滤波PF(Particle Filter)法估算电池初始剩余电量SOC(State Of Charge),提出了先让高SOC电池放电和先给低SOC电池充电的均衡法.该方法相比传统基于充电电压的均衡法能更精确的反映电池能量状态.实验结果表明,对于要求低能耗的系统采用先让高SOC电池放电均衡至±2%平均SOC界限范围;对于要求均衡结果一致性较高的系统采用先给低SOC电池充电均衡至±1%平均SOC界限范围.该均衡方法有效改善了电池组间的不一致性,对于提高电动汽车锂离子电池的使用寿命和续航里程具有实际意义.

A New Bidirection Equalization Method for Lithium-ion Batteries in Electric Vehicles

Cell inconsistency is inevitable due to manufacturing constraint,especially after repeated charging and discharging.Therefore,cell equalization is essentially required in electric vehicles.The bidirection equalization models are established based on the analysis of the inconsistency between the lithium-ion batteries.The PF(particle filter)method is employed to estimate the cell SOC(state of charge).The first high-SOC cell discharge and first low-SOC cell charge equalization algorithms are proposed.This method can reflect the state of battery power accurately when compared with the traditional balancing method based on the battery voltage.The first high-SOC cell discharge method is adopted in low energy system and is balanced to 2%SOC bounds.The first low-SOC cell charge method adopted in high consistency system and is balanced to 1% SOC bounds.The validation experiment results have shown that this method can improve the consistency of the battery effectively,and the proposed algorithm has a certain practical significance to improve the useful life and the mileage of the electric vehicle lithium-ion battery.