Single Power-Conversion Active-Clamped AC/DC Converter Employing Si/SiC Hybrid Switch

Abstract

This article proposes a single power-conversion voltage-fed active-clamped ac/dc converter that uses an Si IGBT/SiC MOSFET hybrid switch. By incorporating two switches at the primary side of the circuit, we removed the full-bridge diode rectifier, and thereby reduced the required number of power devices. Inherent bidirectional active-clamp circuit naturally limits the voltage spike at bottom switches and reuses the energy accumulated in the leakage inductor during both positive and negative grid half-cycles. Also, it offers dual-resonant power transfer paths, so it can deliver the high power with less circuit components. The alternating switching modulation makes one of the bottom switches turn off with hard switching per grid half-cycle while holding other bottom switch on to conduct the current. In contrast, top switches are softly switched with low root-mean-square current. Therefore, the converter with proposed switching modulation enables direct substitution of Si IGBT for an SiC MOSFET at the top on the primary side, and thereby which cuts down the circuit implementation cost. We built a 1 kW prototype converter and confirmed its validity.