Study on Hierarchical Equalization Topology Circuit of Lithium-ion Battery Pack Based on Buck-Boost*

In this study, an innovative two-layer equalization circuit design is proposed, which is based on a Buck-Boost circuit and a switched-capacitor circuit, and successfully realizes one-to-one and many-to-one equalization within a series-connected energy storage lithium-ion battery pack. The Buck-Boost converter is combined with a bus-based strategy to form a bus-based Buck-Boost equalization topology circuit, while a switched supercapacitor bank is combined with a switched-capacitor circuit to form a switched-supercapacitor bank equalization topology circuit, and the two improved equalization topology circuits form a doublelayer equalization topology circuit. On the MATLAB/SIMULINK simulation platform, eight series-connected lithium iron phosphate battery packs are used as the experimental model, and the static, charging and discharging experiments are carried out. The simulation experiments show that this scheme can effectively improve the balancing effectiveness of the equalization circuit, significantly reduce the inconsistency between single cells, and optimize the overall performance of the battery pack.