Short circuit transient behavior of IGBT devices in series connections

The need of devices for medium-range power converters gives rise to a growing interest for the series connections of IGBTs. In this case the control of the voltage sharing across the string of series-connected devices as well as their protection during the short circuit transients are important issues. In this paper is presented an exhaustive analysis of the electrical quantities and device parameters affecting the voltage sharing across the series strings of IGBTs in short circuit conditions In particular, hard switching fault (HSF) and fault under load (FUL) are investigated, in the case of series connections of devices, by carrying out simulation runs and experimental tests in order to understand the behavior of the IGBTs in these critical conditions. Advantages and disadvantages of the voltage sharing techniques are discussed with reference to the failure in short-circuit occurring on the series connection of devices.