Simulation studies and modeling of Short Circuit current oscillations in IGBTs

During Short-Circuit (SC) operations, strong current oscillations of IGBTs can appear. Simulation studies also confirm this. No parasitic inductances are required for such oscillations. A simplified equivalent circuit of the device, which is basically an RC oscillator, is able to reproduce the oscillations. The occurrence of oscillations depends on the model parameters, which can be related to the device structure and other conditions such as the gate resistance value, gate biasing, and DC-link voltage. This paper also shows that application of basic system theory methods to AC small-signal device simulation results (frequency-domain analysis under small-signal conditions) is appropriate to analyze the stability range of the IGBT under Short-Circuit.