Turn-off Overvoltage in SiC Power Electronic Converters

In power electronics converters, understanding the semiconductor turn-off process is key. During turn-off, the semiconductor withstands the bus voltage plus the overvoltage produced in the parasitic inductances and due to the di/dt in the turn-off. In SiC MOSFET turn-off, this overvoltage is critical since these devices operate with higher di/dt and can be operated with blocking voltage close to their breakdown voltage. In this paper, a simple equation-based procedure that allows for an accurate overvoltage calculation in SiC MOSFET turn-off is presented. The proposed step-by-step procedure is applied to calculate the overvoltage during the turn-off of the SiC module CAB016M12FM3 for different gate resistors and switched currents. This analysis can be used to select the correct value of the gate resistor. The obtained results are validated by comparison with LTspice simulation results.