Analysis of 10 kV SiC MOSFET Module Baseplate Parasitic Capacitance Impact on Switching Loss

The parasitic capacitance of a power module baseplate provides a path for displacement current during the switching transient of the power module, which causes extra switching loss and EMI noise. It becomes an increasing concern especially for emerging 10 kV SiC MOSFET modules due to their high voltage and fast switching speed. This paper presents an in-depth analysis of 10 kV SiC MOSFET module baseplate parasitic capacitance impact on switching loss. The turn-on switching energy is divided into four parts, and the module baseplate parasitic capacitance impact on each part of the energy is analyzed. In addition to a constant capacitive energy (i.e., $\displaystyle \frac{1}{2}$ CV
²
), the module baseplate parasitic capacitance also introduces extra V-I overlap energy during voltage fall stage of the turn-on switching transient because it increases voltage fall time. This portion of loss is modeled and quantified. The module baseplate parasitic capacitance impact on switching loss is experimentally evaluated at 6 kV dc voltage and 0 to 50 A currents. This 10 kV SiC MOSFET module baseplate capacitance contributed loss is in the 5-10% range.