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

In this article, a temperature-dependent transient model of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (mosfet) is proposed. The switching transient of the SiC mosfet is divided into four 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 $C_{gd}\times dV_{ds}/dt$ and $L_{s}\times dI_{d}/dt$ 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 dependence of junction temperature $T_{J1}$ of low-side mosfet and junction temperature $T_{J2}$ 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.