Effective measures for improving switching performance of SiC JFET bi‐directional switches

Abstract

Silicon carbide (SiC)-based junction field-effect transistor (JFET) bi-directional switches (BDSs) have great potential in the construction of many power electronic circuits, including matrix converters, multi-level converters, solid-state breakers, and cycloconverters. However, the oscillations of BDSs during turn-on and turn-off transition have great impacts on the stability and reliability of power electronic systems. Two methods are proposed to improve the switching performance, namely using a snubber capacitor and using a ferrite ring. It is found that the use of a snubber capacitor mainly improves the turn-off transition, and the use of a ferrite ring not only damps the oscillation of current waveform during turn-on transition but also makes the waveforms cleaner and less noisy. Besides, both methods can cut down settling time significantly. The effects have been demonstrated by theoretical analysis and verified by experimental results.