Power electronic transformer with reduced number of switches: Analysis of input clamp circuit and a modulation strategy to eliminate input snubber requirement

This paper presents an analysis of the protective snubber circuits in a high frequency transformer (HFT) linked three phase ac/ac power conversion system with reduced number of switches. This topology provides single stage power conversion with bidirectional power flow capability and input power factor correction. This topology is important because of reduced number of switches in the voltage source side (usually the high voltage side). The presence of non-ideal leakage inductance in transformer windings necessitates the use of a snubber circuit for the safe commutation of leakage energy. A new modulation technique is proposed in order to reduce the protection requirements in the source side. This topology with the proposed control technique has been analyzed and simulated. The simulation results confirm the analysis and predicted advantages.