Research on Hierarchical Equalization Technology for Lithium Battery Packs Based on Buck-Boost Circuit

ZHANG Xianlong; GUO Jiahu

doi:10.19329/j.cnki.1673-2928.2026.02.006

Abstract：To address the problem of slow equalization speed of lithium battery packs caused by the increased differences in capacity,voltage,and impedance among individual cells after long-term use,a corresponding solution is proposed.A hierarchical equalization topology based on the Buck-Boost circuit is designed,with the battery state of charge(SOC)selected as the equalization variable.An equalization control strategy combining the average value difference comparison method and the relative range method is adopted to realize step-by-step equalization of lithium battery packs.Firstly,the overall structure,grouping method,working principle of the minimum equalization unit,and calculation process of equalization parameters of the improved equalization topology are clarified.Secondly,the reasons for selecting SOC as the equalization variable and the specific content of the equalization control strategy are explained.Finally,a simulation model of the hierarchical equalization structure is built in the Matlab/Simulink environment to carry out equalization simulation verification,and comparative simulations are conducted with the traditional single-layer equalization topology at the same time.Simulation results show that under the two working conditions of 6-cell and 7-cell battery packs,the equalization speed of the designed hierarchical equalization topology is increased by 78.6%and 79.8%respectively compared with the traditional single-layer equalization topology.The results indicate that the designed hierarchical equalization topology and equalization control strategy are effective and can significantly improve the equalization speed of lithium battery packs.