Analysis of IPM current oscillation under short circuit condition

It is observed that the collector current in an IGBT oscillates under short circuit conditions. In particular, severe oscillation occurs when the IGBT is connected to a current limiting circuit. This current oscillation has some undesirable effects on application circuits using IGBTs or IPMs (intelligent power modules). We have revealed the current oscillation mechanism by means of experiments and simulation. From the results, the IGBT cell structure itself triggers oscillation of the gate voltage and collector current. The parasitic inductance existing in the module and the current limiting circuit connected to the IGBT have an additional influence on the current oscillation behaviour. Current oscillation can be damped successfully by adjusting the parasitic inductance or improving the properties of the current limiting circuit