High speed switching issues of high power rated silicon-carbide devices and the mitigation methods

With faster switching speed and much lower conduction and switching losses, Silicon-Carbide (SiC) semiconductor devices are nowadays gaining more favor in power converters applications. 1200 V and 1700 V SiC MOSFETs are commercially available, which enables more efficient and compact design of high power rated converters. However, the high di/dt and dv/dt associated with fast switching as well as the circuit parasitic elements raise various issues. In this paper, a double-pulse characterization fixture is built to test a 1200 V/100 A SiC device, from which the high speed switching issues, including device current and voltage resonances and spikes, gate terminal resonance, cross-talk, gate driver noise, and electromagnetic interference (EMI), are presented. All the switching waveform resonances and their associated parasitic elements are exploited and explained. Results show that due to these issues, the devices are prevented from full utilization of either the safe operation area (SOA) or the maximum switching speed. Finally, the device model considering all the parasitic elements is tested with a soft-switching circuit-resonant DC link converter, showing that the above stated issues are significantly mitigated.