A bridgeless active-clamp power factor correction isolated SEPIC converter with mixed DCM/CCM operation

A bridgeless active-clamp power factor correction isolated SEPIC converter with mixed DCM/CCM operation is proposed. This converter uses the bridgeless topology to reduce the use of the rectifier diodes and improve the efficiency. The input current of the proposed converter is designed to consist of CCM and DCM parts simultaneously. During some intervals of the line period, the converter is operated in the DCM so that it can obtain a high power factor and confirm to the specification requirement. The main switches in the DCM operation can also achieve the function of zero current turn-on. The converter is partly operated in the CCM to improve the efficiency, although the power factor will be somewhat sacrificed. The active-clamp topology can achieve the ZVS for all switches of the converter and it can also be as the snubber to reduce the spike induced by the leakage inductance of the transformer.