A Temperature-Dependent Analytical Transient Model of SiC MOSFET in Half-Bridge Circuits

In this paper, a temperature-dependent transient model of silicon carbide (SiC) metal-oxide-semiconductor fieldeffect transistor (MOSFET) is proposed. The switching transient of the SiC MOSFET is divided into 4 phases. In each phase, the operations of the MOSFET and its body diode are analyzed and the corresponding equivalent circuits are obtained. The analysis identifies that the Cgd×dVds/dt and Ls×dId/dt induced negative feedback mechanisms, excess charge extraction in the N-base of SiC MOSFET body diode and dynamic transfer characteristics at switching transient are pivotal physical characteristics. The dependency of junction temperature TJ1 of low-side MOSFET and junction temperature TJ2 of high-side MOSFET on the switching behavior of SiC MOSFET is also analyzed and included in the proposed model. Based on the improved understanding of the switching behavior, an analytical model of SiC MOSFET is derived. The analytically derived switching waveforms and switching losses are compared to the test data and good agreement is obtained