Research on Retired Battery Equalization System Based on Multi-Objective Adaptive Fuzzy Control Algorithm

In the secondary utilization of retired batteries in energy storage systems, there exists a significant disparity between batteries, rendering the storage battery pack susceptible to issues such as overcharging and overdischarging during the charging and discharging process. These challenges impose limitations on the available capacity of the storage battery system and may even give rise to safety hazards. To tackle these issues, this study proposes the design of a battery equalization system specifically tailored for retired batteries employed in energy storage systems. A multilayer equalization topology based on a buck-boost chopper circuit is introduced, along with a multi-objective adaptive fuzzy control equalization strategy. This strategy integrates the open-circuit voltage-state of charge (OCV-SOC) characteristic curve of the battery and utilizes voltage and SOC as equalization variables. It governs the magnitude of equalization current based on the battery pack’s SOC state, enabling effective equalization control of the retired battery pack. Simulation results demonstrate that the proposed equalization strategy does not rely on the precise mathematical model of the battery system. When compared with the mean-difference equalization strategy or the single-variable equalization strategy, it exhibits an enhanced equalization rate. Consequently, it fulfills the practical application requirements for equalizing retired battery packs.