Efficient Soft Switching Single-Stage PFC for Low-Power Applications

Single-stage (SS) power factor correction (PFC) converters are applied as the power supply for low-power devices. Usually, the flyback converter is merged with the PFC stage to eliminate the reset winding required for the transformer. This article merges a new resonant forward converter with the buck-boost PFC stage. Thus, reset winding of the forward converter is eliminated while soft switching is achieved. Due to the low flux of the forward transformer core, transformer volume is reduced. Also, for the same volume of the transformer, transformer losses can be reduced in comparison to the flyback converter. The proposed converter is analyzed, and design considerations are discussed. A prototype converter is implemented. According to the experimental results, high efficiency and low total harmonic distortion (THD) are achieved.