Understanding switching losses in SiC MOSFET: Toward lossless switching

Abstract

Due to the limitation in circuit measurements using current and voltage probes, the conventional ways of measuring switching losses lack the physical insight of the complicated witching process in power devices such as the SiC power MOSFET. This paper seeks to have a better understanding of the dynamic turn-on and turn-off processes of the SiC power MOSFET. Using a detailed finite element simulation model in TCAD Sentaurus, a better and accurate understanding of switching losses in SiC MOSFET is obtained. The physical insights during switching process, as well as the impact of gate resistance and common source parasitic inductance are studied. Based on the results obtained in this study, SiC MOSFET can achieve lossless switching for both turn-on and turn-off if certain conditions of its gate drive circuit and load current conditions are met. Therefore this analysis provides a theoretical guidance for high voltage SiC MOSFETs to be used in extremely high switching frequency applications.