Novel Bidirectional Voltage Equalizer Based on Double Output Dual Switch Flyback Circuit

Voltage inconsistency occurs during charging and discharging of battery pack in series which affects its capacity and life if no measures are taken. A bidirectional equalizer based on dual switch flyback transformer is presented for making the voltage of lithium battery pack consistent efficiently. First, the transformer is taken as the carrier of energy transfer, and the forward and reverse working principle of the equalization circuit is analyzed. Second, according to the different direction of energy transfer, the corresponding equilibrium strategy is designed. Whether to stop equalization is judged by the maximum voltage difference between cells. Finally, a set of platforms containing 12 battery cells are built to perform equalization experiments. The results show that maximum voltage difference between the cells are less than 30 mV after the equalization which proved the feasibility of the proposed scheme. Compared with the existing mainstream equilibrium structures, the structure proposed in this paper has faster equilibrium speed and higher efficiency. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.