A single-stage bridgeless ZVS AC/DC converter for power-factor-correction applications

Abstract

A novel single-stage bridgeless AC/DC power-factor-correction (PFC) converter with galvanic isolation is proposed in this paper. An auxiliary switch and a clamp capacitor are connected in parallel with primary side of the transformer to reduce the voltage stress of main and auxiliary switches. The resonant inductance and the resonant capacitor are resonant to achieve zero-voltage-switching (ZVS) for both main and auxiliary switches. The main switches share the same driver signal, and the converter does not need to sense the positive or negative ac input voltage, so it could be easily implemented with available average current model control IC. The detailed ZVS operation principle of the system is presented. The proposed converter has the advantages of minimum component count, galvanic isolation and higher efficiency. Simulation and experimental results are presented for a 3000 W prototype circuit at 85 kHz switching frequency to demonstrate the effectiveness of the proposed converter.