Design of IGBT gate drive circuit with SOA consideration

Over-current protection for IGBT (insulated gate bipolar transistor) has created a great amount of attention in recent years. Over-current protection covers both for overload protection and short circuit protection. The protection circuit should be able to distinguish these two fault conditions and its response should be different. However in order to implement proper sensing, comparison and time delay functions, the protection circuit usually becomes complicated where active components and integrated circuits are used. In this paper, a simple IGBT gate drive circuit with only 9 passive and 1 active components was proposed to implement the complete function of over-current protection. The circuit is able to provide a suitable delay time prior to the gate shutdown in order to operate the device closer to but still within the limit of the safe operation area (SOA). The circuit was analysed theoretically and the performance was verified with experimental results.