Single-stage soft-switching PFC converter based on DCVM buck and flyback converters

Single stage PFC converters have interesting characteristics of simple topology and control circuit, low number of active and passive elements and low cost. These kinds of PFC converters have disadvantages such as high voltage stress, especially in the light load and heavier loss comparing with a typical DC-DC converter. These characteristics seriously limit their practical applications. In this paper a new single-stage soft switching PFC converter is presented. The most important advantage of the proposed topology is that the voltage across the bulk capacitor is low even at the light loads and the input current is continuous. The proposed topology is derived from a DCVM buck converter integrated with a flyback converter. Also an active clamp is added to the proposed converter to achieve soft switching, reducing losses and recycling energy trapped in the leakage inductance of flyback transformer. This structure significantly improves the justification of topology for practical applications. The presented simulation results of the proposed converter justify the theoretical analysis.