Universal input single-stage PFC AC/DC converter with reduced DC-bus voltage stress

High DC bus voltage stress and low conversion efficiency limit the practical application for single stage power factor correction (PFC) AC-DC converters. This paper presents a cost-effective approach to alleviate these issues based on a conventional BIFRED AC/DC converter. In the proposed topology, a flyback transformer and a small serial connected inductor are implemented to replace the traditional input PFC inductor, and a cost-efficient lossless snubber is also proposed to reduce the turn-off spike of the main switch. The experimental results of a 20 V@4.5 A prototype indicate that the proposed technique can suppress the DC voltage below 400 V through the entire universal input range, while keeping the efficiency and power factor above 81% and 0.95 respectively.