Study of a charge/discharge equalizer

Because the characteristics of LiFePO₄ batteries are different, it may cause overcharge/overdischarge, and reduce the cycle life of battery when series-connected batteries are used. This paper proposed a charge equalizer that utilizes an interleaved active clamp flyback converter, which connected to a battery string in the charging/discharging process. Based on a clamp capacitor and leakage inductances, the switching surge voltage and the output ripple current can be reduced. The duty cycle is approximately 0.5, the switch is turned on with zero-voltage switching. The initial voltages of four batteries are different before the battery string is discharged. In the discharging process, the voltages of the batteries will be balanced and equal. The performance of charge equalizer is validated in simulation.