Investigation of the mechanism of gate voltage oscillation in 1.2kV IGBT under short circuit condition

The mechanism of the gate oscillation under short circuit condition was studied by experiment and simulation. In the both ways, dependence of input DC-link voltage V cc and stray inductance Le on the gate oscillation was examined to clarify the cause. It has been found that under short circuit a high electric field formed in the collector side and hole transit time delay plays a critical role for the onset of oscillation. Based on the model, its parametric dependence can be clearly interpreted. In addition, the design to suppress the oscillation has been discussed.