Double-Layer Lithium-Ion Battery Equalization Control Strategy Based on Fuzzy Logic Control

Lithium-ion batteries are known for their long lifespan and high energy density, making them widely used in energy storage systems. To address the issue of inconsistent battery capacity within lithium-ion battery packs affecting the power and energy performance of energy storage systems, this paper optimizes the structure of a single-layer Buck-Boost converter balancing topology. An improved multi-layer balancing topology is designed, proposing the use of Buck-Boost converters for intrapack balancing and flyback converters for inter-pack balancing. Using battery state of charge (SOC) as the balancing variable, the topology achieves simultaneous balancing within and between battery groups. A fuzzy controller dynamically adjusts the magnitude of the balancing current to enable efficient energy transfer between batteries, thereby improving the balancing efficiency of the battery pack. Simulation analysis conducted in MATLAB/Simulink demonstrates that the improved hierarchical structure based on fuzzy control achieves short balancing times, high efficiency, and effectively mitigates inconsistencies within battery packs.