New Bridgeless Buck PFC Converter with Improved Input Current and Power Factor

The bridgeless buck power factor correction (PFC) converters feature the merits of low output voltage and high efficiency while their inherent dead angles in the input current will deteriorate the input current harmonics and power factor (PF). Aiming to reduce the dead angles, a new bridgeless buck PFC converter is proposed in this paper. Through integrating the main buck circuit and the auxiliary flyback circuit with one magnetic core, the dead angles in the input current of the proposed bridgeless buck PFC converter is eliminated so that the PF and input current harmonics are improved. The proposed bridgeless buck PFC converter is designed to operate in discontinuous conduction mode (DCM) with the merits of simple controller and nature current shaping ability. A new logic control circuit is provided. The detailed theoretical derivations and design consideration are presented. The experimental comparison among the proposed bridgeless buck PFC converter, the conventional buck PFC converter, and the conventional bridgeless buck PFC converter is displayed to validate the effectiveness of the new converter.