Impact of $RC$ Snubber on Switching Oscillation Damping of SiC MOSFET With Analytical Model

Abstract

As the most popular wide bandgap (WBG) power device, the silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) has been widely adopted in the power electronics applications and brings in the benefits, including reduced switching losses, enhanced switching frequency, and improved power density. However, the switching oscillation and the electromagnetic interference (EMI) become more serious due to the rapid switching speed of SiC MOSFET. Thus, adding $RC$ snubber branch is considered as an effective method to suppress such unwanted oscillation in the early works. In this article, the switching transient of SiC MOSFET with $RC$ snubber is investigated with an analytical model based on the finite-state machine (FSM). The accuracy of the proposed analytical model can be verified by comparisons between the calculated and measured waveforms during the switching transition. In addition, the impacts of the $RC$ snubber on switching oscillation, switching loss, and high-frequency (HF) EMI noise have been comprehensively investigated based on the model, which shows that the added $RC$ snubber can effectively avoid the switching oscillation and reduce the level of HF EMI without increasing switching loss.