Joint SOC-Temperature Active Equalization for Lithium-Ion Battery Packs via a Dynamic Grouping Topology

Abstract

Battery equalization technology can enhance the consistency of battery packs and extend their service life. However, most existing equalization strategies tend to focus on increasing the equalization speed while neglecting temperature variations among individual cells, which poses significant safety risks. To address these issues, this paper proposes a joint state of charge (SOC)-temperature active equalization strategy based on a dynamic grouping topology. First, a dynamic grouping topology integrating a reconfigurable circuit and a flying-inductor is proposed, enabling energy transfer between any cells. Second, discrete dynamic models for SOC and temperature are respectively constructed, and the deviations of each variable from its mean are combined to form the optimization objective through an adaptive weighting method. Then, a Tent-enhanced fireworks algorithm (Tent-EFWA) is applied to optimize the charge/discharge decisions for each cell and generate the corresponding PWM control signals. Finally, simulation studies are conducted in MATLAB/Simulink. Compared with the traditional mean-difference strategy, the temperature difference is reduced by 38.71% under static conditions, while under charging and discharging conditions, it is reduced by 48.35% and 58.62%, respectively. These results verify the effectiveness of the proposed strategy in improving both the consistency and safety of battery packs.