A ZVS based bidirectional Equalizer for Battery Equalization

A soft-switching bidirectional CUK equalizer is presented to balance cells series-connected in the battery string efficiently. The presented equalizer achieves zero-voltage switching (ZVS) and a high efficiency equalization with a resonant tank containing two resonant capacitors, one resonant inductor and two auxiliary switches. The resonant tank in the equalizer reduces switching loss and improves equalization efficiency compared with hard-switching equalizers. The topology and operating principle of the presented equalizer are given in this paper. An experimental platform is designed and experimental results show that the efficiency increases around 2% -3% compared with a zero current switching equalizer at 300kHz switching frequency.