Experimental Verification of the Switching Loss Reduction Effect and Characteristic Fluctuation of SiC MOSFETs Dependent on Gate Drive Voltage

Abstract

The switching frequency of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) should be increased to maximize their benefits in power conversion circuits. However, the switching loss increases when the switching frequency is increased. Generally, the gate resistance is designed to be small to reduce the switching loss for one cycle. However, SiC MOSFETs have a higher parasitic gate resistance than Si power devices. This paper proposes reducing the switching losses by “overdriving” the SiC MOSFETs, in which the gate voltage V_g is designed to be higher than the rated gate-source voltage of the SiC MOSFET. The relationship between gate voltage V_g and switching loss is clarified both theoretically and experimentally. Additionally, the effect of “overdrive” on the long-term reliability of SiC MOSFETs is evaluated by conducting continuous switching tests. The results show that “overdrive” can maximize the benefits of SiC MOSFETs based on the expected lifetime of the power conversion circuit.