Turn-on Induced Voltage Overshoot and Oscillations of Non-Switching SiC MOSFETs Modules Connected to a Common DC Busbar

This paper presents an experimental investigation of turn-on-induced voltage oscillations on non-switching SiC modules sharing a common DC busbar. Results show that the turn-on transient of one SiC module generates significant voltage overshoots on the modules connected to the common DC busbar. The magnitude of this turn-on-induced overshoot has a similar or greater value than the conventionally analysed turn-off overshoot of the switching device. Moreover, the peak-to-peak magnitude of the oscillations is shown to be dependent on the dv/dt rather than the DC voltage. Consequently, the induced over-voltages present a higher per-unit magnitude for lower operative voltages. Double pulse test results show that one SiC module switching on at 900 V/250 A generates an induced overvoltage of 1.3 p.u on a DC parallel connected non-switching module, considerably higher than the 1.12 p.u. turn-off voltage overshoot.