Abstract:
The silicon carbide (SiC) metal-oxide- semiconductor field-effect transistor (MOSFET) exhibits serious voltage overshooting and oscillation during high-speed turn-off, which reduces the voltage margin of the device. The snubber circuit is usually utilized to regulate the turn-off voltage trajectory of the SiC device. However, the existing researches overlook the interaction between the SiC device and the snubber and ignore the temperature-dependent properties of the snubber, which limits the application of the snubber circuit. Motivated by these issues, this paper proposes a novel snubber circuit based on the lead zirconate titanate (PZT) piezoelectric ceramic. With the aid of the temperature characteristics of the PZT, the in-depth interaction models between the half-bridge topology and the PZT snubber are created. Moreover, based on the characteristic equation-root locus tool, the coupling principles of the SiC device and PZT snubber are quantitatively demonstrated. Additionally, the temperature-dependent performances of multiple snubber circuits are assessed. Comprehensive experimental results ensure that the overshooting and oscillation of the turn-off voltage can be well suppressed by using the target-designed PZT, which verifies the accuracy of the design method. Different from the traditional RC snubber, it is preferred that the suppression effect of the PZT snubber is enhanced under the increased ambient temperature. The models and findings might promote the stability analysis of the SiC MOSFET and the packaging integration of the power module with the snubber circuit.