A novel soft-switching high-frequency transformer isolated three-phase AC-to-DC converter with low harmonic distortion

A high-frequency transformer isolated, fixed-frequency, 3-φ single-stage ac-to-dc converter using a boost-integrated bridge converter that employs a new gating scheme is proposed. This converter enjoys natural power factor correction with low line current harmonic distortion and symmetric high frequency voltage and current waveforms while ensuring zero-voltage switching for all the switches for a wide variation in load and line voltage. Various operating modes of the converter are presented and analyzed. Based on the analysis, design curves are obtained and an optimum design is given. A design example is presented. Results obtained from SPICE simulation and a 500 W output experimental prototype are given to verify the performance of the proposed converter for varying load as well as line voltage.