A Power Electronic Transformer for Three Phase PWM AC/AC Drive with Loss Less Commutation and Common-mode Voltage Suppression

This paper presents a novel topology for the generation of adjustable frequency and magnitude PWM three phase ac from a balanced three phase ac source with a high frequency ac link. The proposed power electronic transformer system provides single stage power conversion with bidirectional power flow capability. This topology along with the proposed control has the following advantages : 1) Input power factor correction, 2) Common-mode voltage suppression at the load end, 3) High quality output voltage waveform (comparable to conventional space vector PWM modulated two level inverter) and 4) Minimization of output voltage loss, common-mode voltage switching and distortion of the load current waveform due to leakage inductance commutation. A loss less source based commutation technique for the leakage energy has been proposed. This results in soft switching of the output side converter. The entire topology along with the proposed control scheme has been analyzed and simulated. The simulation results verify the operation and advantages of the proposed power electronic transformer.