Adaptive Equalization Method of Lithium Battery Module Based on Time-Varying Characteristics of Voltage and SOC

Abstract

In today's increasingly frequent use of batteries, battery management has become even more important. In order to improve the balancing rate of lithium battery pack systems, a fuzzy control balancing scheme based on PSO optimized SOC and voltage membership function is proposed. Firstly, the underlying balancing circuit is composed of buck-boost circuits and adopts a layered balancing strategy; Secondly, using the states of different battery remaining capacities (SOC) and real-time battery voltage as inputs to the fuzzy logic algorithm, the constraints on the equilibrium current are adjusted; Again, use the membership function optimized by PSO for fuzzy control, and directly use the duty cycle of the switch tube as the system input; Finally, change the charging and discharging status of the battery pack and conduct simulation experiments. The results showed that compared with traditional fuzzy control methods, the proposed system increased the balancing speed by about 36% in the static state, and increased the balancing speed by about 14% and 37% in the charging and discharging situations, respectively. This optimization scheme combines the stability provided by fuzzy algorithms with the robustness and generality of PSO algorithms, ensuring safer and more stable operation of battery packs, which can provide reference for improving battery pack performance research.

Keywords: PSO, fuzzy control, active balancing, adaptive technique