Research on Equalization Strategy of Lithium Battery Pack Based on Maximum SOC

Aiming at the inconsistency of each battery in the use of series lithium-ion battery pack, the switching resistance discharge passive equalization topology of series battery pack with four batteries is taken as the research object, and the control strategy based on SOC maximum value as the equalization variable is investigated. Based on the software MATLAB/Simulink, a balanced charge and discharge model of series battery pack is built. The performance of the control strategy with maximum SOC as the equilibrium variable is simulated, and compared with the balance control strategy based on minimum SOC and traditional balance control strategy based on residual capacity. The results show that the standard deviation of the control method with the maximum SOC as the equilibrium variable is 3.8% of the minimum SOC and 1.75% of the traditional method based on residual capacity when the equilibrium error is 0.1%. Meanwhile, the equalization completion time is reduced by 41% compared with the minimum SOC and 70% compared with the traditional residual variable. The efficiency of the equalization control method is relatively high, and it can solve the inconsistency problem and greatly improve the charging time, which can effectively improve the capacity utilization rate of the battery.