Flyback battery equalizer with voltage doubler rectifier

In this paper, a new flyback battery equalizer employing a voltage doubler rectifier is proposed. The proposed circuit transfers electric charges by utilizing the resonance between the transformer leakage inductor and secondary capacitor. Therefore, the proposed battery equalizer can reduce the switch turn off loss and snubber loss by a sinusoidal shaped current. Furthermore, the voltage stress on the rectifier diodes can be clamped to the battery stack voltage. The operational principle and characteristics are presented. To verify the performance of the proposed circuit, experimental results from four 3.8 V and 2600 mAh lithium-ion batteries are presented.