Analytical Switching Transient Model of TO-247-4 Packaged SiC MOSFETs and Comparison with TO-247-3 Devices

SiC MOSFETs in TO-247-4 package (Kelvin-source configuration) offers the advantages of faster switching transients and lower switching losses compared to TO-247-3 packaged (common-source configuration) SiC MOSFETs. Due to small value of the common-source inductance in TO-247-4 package, switching dynamics of SiC MOSFETs can be significantly different. This paper presents a detailed analytical switching transient model of TO-247-4 packaged SiC MOSFETs where SiC Schottky diode (SBD) is used as a freewheeling diode. The model considers detailed nonlinear device characteristics of both SiC MOSFET and SiC SBD along with the effect of the external circuit parasitics. The proposed model is validated through behavioral simulation and experiment for a 1.2kV TO-247-4 packaged SiC MOSFET and SBD pair for a range of operating conditions. In addition, switching loss, (di/dt) and (dv/dt) obtained for the TO-247-4 packaged SiC MOSFET are compared with TO-247-3 packaged device.