A Compact Inductively Coupled SiC MOSFET Snubber for Quasi-Zero-Voltage Turn-On, Switching Oscillation, and Voltage Spike Suppression

Turn-off voltage spikes and switching oscillations caused by fast switching characteristics remain a pressing challenge for SiC MOSFETs. Consequently, an enhanced inductively coupled snubber for oscillation and overvoltage suppression is suggested in this study. It can also achieve a quasi-zero-voltage turn-on. It mainly consists of two parts: an inductively coupled compact PCB circuit and an RCD clamp circuit. First, the LTspice simulation is used to determine the range of parasitic inductance that can realize quasi-zero voltage switching. Second, the clamping circuit is determined by the theoretical circuit analysis for voltage spike reduction. Finally, all the snubber circuit parameters are substituted together into the established characteristic equation, and the pole assignment method is utilized to determine the required equivalent inductance and resistance by the inductively coupled circuit for fully damped oscillations. In order to better use available space and preserve the high-frequency properties, a small inductively coupled PCB circuit is constructed. The experimental results demonstrate that the suggested enhanced snubber considerably lowers the switching loss while achieving good overvoltage and oscillation suppression.