A power electronic transformer-based three-phase PWM ac drive with lossless commutation of leakage energy

This paper proposes a novel dc/ac converter topology with a high frequency ac-link for three-phase adjustable speed PWM ac drives. Such drives find applications in UPS systems and renewable energy sources like solar and fuel cells. This topology provides single-stage power conversion with bidirectional power flow capability. The high frequency transformer offers the benefits of galvanic isolation and high power density. The topology proposed in this paper minimizes the number of switching transitions between the transformer winding and the load. This reduces common-mode voltage switching and improves the output voltage profile. A lossless source based commutation technique has been developed for the commutation of the energy stored in the leakage inductances of the high frequency transformer. This method also results in zero current switching (ZCS) of all four-quadrant switches in the load side converter. The proposed topology has been analyzed and simulated. Simulation results that verify the operation of the proposed topology are presented.