Effects of Basal Plane Defects on the Performance of Voltage Source Converters

Impact of SiC MOSFETs bipolar degradation on the performance of a Two-Level voltage source converter (2-L VSC), operating in a synchronous rectification mode, in terms of efficiency is presented. It is assumed that basal plane defects (BPDs) propagating from the epitaxial layer to the drift layer lead to Shockley-type stacking faults which cause a significant forward voltage increase of the body diode. Simulation models of the 2-L VSC were built to explain the dependency of BPDs on different electrical parameters. Evaluation of the power losses of the converter considering 30 BPDs in the chip area of the device showed a 12% increase on the switching losses while the conduction losses increased only by 8%. This has a significant impact on the overall power converter reliability which must be taken into account in applications where power density is a stringent design requirement as in offshore wind farm application.