Multistage Variable Current Pulse Charging Strategy Based on Polarization Characteristics of Lithium-Ion Battery

The rapid charging strategy of lithium-ion batteries is the basis for large-scale application of electric vehicles. This paper proposes a four-stage variable current pulse charging strategy for lithium-ion batteries. Based on the commonly used equivalent circuit model, this paper proposes a second-order RC equivalent circuit model considering the voltage hysteresis effect. The battery state of charge (SOC) is estimated using the unscented Kalman filter algorithm based on temperature and capacity correction (TQ-UKF). The pseudo-two-dimensional (P2D) model was used for COMSOL simulation to determine the safe charging current under different SOC. Taking the safe charging current as the threshold, the genetic algorithm (GA) is used to solve the optimal charging current for the weights of different charging time and charging loss. Finally, the pulse charging in the high SOC stage is combined with the optimal charging current to optimize the lithium-ion battery charging process. Compared with the traditional constant current constant voltage (CCCV) charging strategy, the charging strategy proposed in this paper can improve the charging capacity and battery utilization while ensuring the charging time.