An Adaptive and Efficient Equalizer Based on Bidirectional Flyback Conversion

Equalizers are used to improve battery pack consistency and extend battery life, which has been widely applied in the field of electric vehicles and energy storage. However, the traditional equalizers exhibit drawbacks such as large size, low efficiency, and single equalization function. Therefore, an adaptive and efficient equalization topology based on bidirectional flyback transform is proposed. The single winding flyback converter bidirectional excitation mechanism is introduced, and only one converter is needed for the whole circuit, realizing low cost and high efficiency equalization. Using odd-even cell grouping control to drive bidirectional excitation, both cell-to-pack and pack-to-cell equalization paths are achieved. Further, three modes including charging, discharging, and automatic equalization are supported, making it possible to flexibly choose the suitable equalization approach to achieve fast equalization. Finally, a battery pack experimental platform was built. The results showed that the average equalization efficiency is more than 95%. The voltage difference of the batteries is less than 5mV after equalization, significantly improving the consistency of the pack. Compared with conventional equalizers, the proposed equalizer is more compact, flexible, and efficient.