New zero-voltage-switching bridgeless PFC, using an improved auxiliary circuit

This study presents a new zero-voltage-switching (ZVS) single-phase bridgeless PFC, using an improved auxiliary circuit to achieve ZVS for all main switches and diodes. Compared to other ZVS bridgeless PFC converters with no extra voltage and/or current stresses, the converter presented here uses lower component count. Since the presented PFC uses a bridgeless rectifier, there are only two semiconductor components in the main current path instead of three in conventional single-switch configurations. This property decreases the conduction losses, significantly. Moreover, ZVS removes switching loss of all main switches and diodes. Furthermore, since resonant current passes only through the auxiliary circuit, there is no extra current and/or voltage stress on the main switches and diodes. The auxiliary switch operates in zero-current conditions; therefore it does not introduce any switching loss. The presented converter just needs a simple non-isolated gate drive circuitry to drive all switches. Nine stages are explained for each ZVS switching period. Design considerations and a control strategy are also explained. Finally, the converter operation is verified by simulation and experimental results.