Gate driver with feed forward control of turn off performances of an IGBT in short circuit conditions

This paper presents a short overview of an IGBT short circuit failure due to over-voltage, and discusses some protection methods. Every new generation of high power IGBT becomes faster and faster, with the collector current fall time of less than 100 ns, sometimes even 50 ns. Fast switching of the collector current, especially at current of 200 A or more, introduces a problem of turn off over- voltage. In case of overload or short circuit, the peak voltage on IGBT may exceed the break down voltage. As a result, the device can catastrophically fail in several tens of nanoseconds after collapse of the collector emitter voltage. To prevent a catastrophic failure, an advanced gate drive circuit has to be used instead of a standard gate drive with pure resistive gate control. A novel IGBT gate driver based on feed-forward control of the collector current slope and the collector emitter over-voltage in short circuit conditions is presented in this paper.