Study of modulation techniques applied to full bridge single-phase inverters based on wide-bandgap semiconductors

Abstract

Wide-band gap (WBG) devices are gradually replacing standard Si semiconductors in power converters. This is due to the fact that WBG devices exhibit lower capacitance and on-resistance and besides, as they can switch at much higher frequencies, high-quality output voltage can be achieved. Additional improvements can be obtained by using new modulation techniques. In this paper, four modulation techniques (Bipolar, Unipolar, Discontinuous 1P and Discontinuous 2P) have been studied. All of them have been implemented on a WBG-based full-bridge single-phase inverter. In order to assess the output voltage quality, Total Harmonic Distortion (THD) and Weighted Total Harmonic Distortion (WTHD) have been computed. Overall power losses and Common Mode Voltage (CMV) have been computed too. In terms of output voltage quality, better results are obtained with either unipolar or any of the discontinuous modulation techniques. Discontinuous techniques show also excellent results as for power losses. The best CMV results are obtained with bipolar modulation.