An SiC-MOSFET-Based Nine-Switch Single-Stage Three-Phase AC-DC Isolated Converter

Three-phase power factor correction rectifiers followed by a dc-dc isolated converter are widely used for conversion of three-phase ac to isolated dc output used for high-power telecommunication loads. In this paper, a reduced device count nine-switch converter topology, which integrates the two stages of a conventional three-phase ac-dc power supply with an isolated dc output voltage for telecom applications is proposed. A novel modulation scheme using three separate 120^{\circ } phase-shifted high-frequency carriers for the three legs of the proposed converter is developed to drive the switches. It is shown that such modulation scheme leads to interleaved operation of the three dc-dc resonant converters integrated within the proposed topology resulting in low output dc voltage ripple. Justification is provided for the choice of the SiC MOSFET as the enabling technology for the converter. The proposed system with the modulation scheme is validated with a 1.5-kW laboratory prototype, which meets the Energy Star 80PLUS platinum efficiency standard for all loads.