Design of Active Battery Equalization Scheme Based on Buck-Boost

To solve the problem of SOC imbalance in Li-Ion battery packs after cycles of charge and discharge, this paper proposes an active equalization circuit based on Buck-Boost. Several independent inductors are used as the medium for energy transfer among the single cells. The energy of the single cell with the highest SOC will be transferred to others. Based on the analysis of the charge and discharge process in the equalization circuit, two schemes are designed for comparison in simulation experiments. During the equalization process, the SOC curve and the equalization parameters were recorded. The simulation results show that the circuit can achieve 80% energy utilization, and the equalized cells' SOC variance is maintained at a very low order of magnitude. The alternating equalization control scheme, using a parallel energy transfer method, can achieve faster equalization speed.