Soft-Switching Bridgeless Buck PFC With Low THD

In this article, a modified soft-switching bridg- eless buck converter is introduced. In the proposed converter, input current dead angle is eliminated by applying a simple auxiliary circuit. In addition, by operating under discontinuous capacitor mode and discontinuous capacitor voltage mode conditions, high efficiency and low total harmonic distortion (THD) are achieved for a wide range of load variation. The proposed converter is analyzed, and design considerations are discussed. A prototype converter is implemented. The efficiency of 93.7% and the THD of 4.3% are achieved using low-cost insulated gate bipolar transistor switches and diodes for the output voltage of 24 V. The proposed converter is controlled by a simple pulsewidth modulation controller.