Investigation of oscillations in a 6.5-kV, 1-kA SiC diode module

SiC technology is attractive for power devices, as it potentially offers many advantages over traditional Si-based devices. However, many issues still need to be properly addressed in order to become a popular and cost-effective alternative to Si devices. One of these issues are high-frequency oscillations that appear during commutation, which limit the switching speed of the device and can produce undesired EMC problems. This paper analyzes the source of the oscillations that appear during the turn-off transient of a recently developed SiC PiN diode module (6.5 kV, 1 kA). A behavioral model derived from the device characterization was elaborated and verified. Through simulation, the main ringing sources are identified and assessed. The positive effect of an RC snubber circuit for dampening the oscillations is presented and experimentally verified.