A Step-Up DC–DC Converter With a Resonant Voltage Doubler

A step-up dc-dc converter with a resonant voltage doubler is proposed. The proposed converter is composed of an active-clamp circuit and a resonant voltage doubler. The active-clamp circuit, which is controlled by dual asymmetrical pulsewidth modulation of the primary side, reduces the voltage spikes of main switches and limits the voltage stress of the switches as the maximum input voltage. In addition, the resonant voltage doubler of the secondary side provides two resonant-current paths formed by the leakage inductance and the output resonant capacitors, and zero-current-switching turn-off of diodes can be achieved by their resonant current. Thus, the losses of the output diodes due to the reverse-recovery problem can be removed. In addition, the voltage stress of the output diodes is clamped to the output voltage. The operation and analysis of the proposed circuit is presented in detail. To verify the performance of the proposed converter, experimental results are carried out for a 1.2-kW dc-dc converter with a constant switching frequency of 70 kHz.