A Novel High-Voltage-Gain Quasi-Resonant DC–DC Converter With Active-Clamp and Switched-Capacitor Techniques

We propose an isolated high-voltage-gain quasi-resonant dc–dc converter with a bifunctional circuit for the renewable-energy applications. The proposed converter adopts an interleaved connection in the primary side, reducing input-current ripple, and includes the bifunctional circuit operating as the switched-capacitor cells and two active-clamped circuits simultaneously. The converter realizes high-voltage-conversion ratio without using extreme duty ratio, and the voltage spike due to the leakage inductance of the isolation transformer is clamped. In addition, an output voltage doubler in the secondary side comprises a series resonant circuit and then obtains zero-current switching turn-
off
of rectifying diodes; the diode reverse-recovery problems are also alleviated. A 320 W laboratory prototype that operates at input of 26–34 V and output of 400 V is fabricated to verify the effectiveness of the proposed converter.