Active Fault Protection for High Power IGBTs

An active fault protection method is proposed to prevent the IGBTs from being damaged should they be under over-current and short circuit fault conditions. A closed-loop gate drive method is used to effectively control the IGBT turn-off switching speed independent of the fault type or resultant over-current level. Compared with conventional solutions, the proposed method can limit fault current level, minimize energy loss with fast shut down transient, and control voltage overshoot. Also, no additional hardware circuit or soft shut down process is need. Even if an over-current fault condition can not be effectively detected, the automatically controlled IGBT turn-off switching speed can avoid a dangerous voltage overshoot across the power device. This new feature can significantly improve the robustness of the power system and cannot be achieved with the conventional approaches.