Effect of capacitive current on reverse recovery of body diode of 10kV SiC MOSFETs and external 10kV SiC JBS diodes

The body diodes of 10kV SiC MOSFETs can be used as anti-parallel diodes in medium voltage converters instead of widely used SiC JBS and PiN diodes. Characterization of switching loss of the body diodes is required to evaluate its candidature for replacement of JBS/PiN diodes. Normally, double pulse test setup is used to observe the reverse recovery behavior of the diodes. But, in high voltage diodes, due to large dv/dt the capacitive current becomes significant, and it superimposes on the reverse recovery current waveform of the diode, misleading the reverse recovery loss data, if the capacitive current is ignored. In this paper, contribution of the capacitive current in the reverse recovery is segregated, which helps in determining actual reverse recovery loss of the diode in double pulse test circuit. Two-slope turn-on characteristic of 15kV SiC IGBT is employed to support the existence of this capacitive current. Using the proposed segregation technique, reverse recovery of the body diode of 10kV SiC MOSFETs is compared with that of 10kV SiC JBS diode.