Analysis on the Self-Sustained Oscillation of SiC MOSFET Body Diode

Under certain conditions, self-sustained oscillation may occur during reverse recovery transient of high-side silicon carbide (SiC) MOSFET body diode in the half-bridge circuit. In this article, two distinct positive feedback mechanisms that can excite the self-sustained oscillation are identified based on the double-pulse test. To investigate the instability of the two types of oscillation, a small signal ac model of the half-bridge circuit is proposed. With the model utilized, the parametric sensitivities of various parameters on the self-sustained oscillation are analyzed. The analyses reveal the oscillatory criteria, which provides effective guidelines to prevent the oscillation. In the end, the oscillation prevention guidelines are validated by the experiment. The experimental results demonstrate that the proposed theoretical treatment can provide reasonable guidelines to suppress the two types of self-sustained oscillation.