Comparative study of self turn-on phenomenon in high-voltage Si and SiC power MOSFETs

High dv/dt caused by the fast switching of high voltage induces misfiring of adjacent power MOSFETs by a fluctuating gate voltage. This is known as the self turn-on phenomenon. The gate voltage of vulnerable power MOSFETs is increased by charging the Miller capacitance with the abrupt application of a drain voltage, even though the gate drive circuit maintains the off condition. This study analytically derives the model equation of gate voltage behavior and experimentally compares the difference in the phenomena between high-voltage Si super-junction MOSFETs and SiC MOSFETs on the basis of static C-V and dynamic characteristics. The results show that the gate voltage of SiC MOSFETs is insusceptible to a high-voltage fast switching operation.