High Power Factor Bridgeless Integrated Buck-Type PFC Converter With Wide Output Voltage Range

Due to the input current dead zones, the buck power factor correction converter has to set a fixed output voltage for a tradeoff between the total harmonic distortion (THDi) and efficiency. Thus, many converter-cell integrated buck-type converters have been proposed to eliminate the dead zones, which unfortunately deteriorate efficiency due to the extra components.This article proposes a group of bridgeless buck-type integrated topologies. Then, a dead-zone-free bridgeless buck-type topology with a wide output voltage range is targeted for further study. The studied converter operates in the buck+flyback mode and can automatically change to flyback mode when the dead zones occur, which only requires a simple control. Moreover, an integrated transformer based on an E-E core is investigated to reduce cost and volume. The bridgeless operation modes are introduced, followed by the PF and THDi analysis to optimize its performance. Prototypes are built and tested, which confirm the effectiveness of the converter and the integrated magnetic.