A new gate circuit performing fault protections of IGBTs during short circuit transients

Short circuit faults of IGBTs determine overcurrent through the devices subsequently to a turn-on switching or during the on-state condition, leading respectively to hard switching fault (HSF) or fault under load (FUL). Firstly, the state of the art as appearing in literature is recalled and discussed. A new short-circuit protection scheme, which allows protection of IGBT devices against fault under load and hard switching fault transients, is presented. It performs the fault current limiting action within the short circuit time, and subsequently forces the device to gate on again in a tentative turn-on. Moreover, the proposed circuitry allows strong bounding of the peak of the current in FUL transients. The validity and correctness of the proposed approach has been extensively validated by experimental tests.