Transformerless single-stage AC/DC converter with direct power transfer

A transformerless single-stage AC/DC converter is presented in this paper. With direct power transfer, a portion of input power is only processed once resulting in enhanced conversion efficiency. The intermediate bus voltage is kept below 400 V in universal line input even in light load condition. Moreover, the absence of transformer reduces size and cost of the converter and the switching devices are clamped to output voltage. Using this concept, an Integrated Boost and Buck-Boost converter (IBoBuBo) is proposed to perform both high power factor and tight output voltage regulation. The circuit operation, analysis and simulation results will be addressed in the paper.