A More Reliable and Sensitive Overcurrent Detection Method in DC Breaker Surge Current Applications via VGE as a Desaturation Precursor

Desaturation has always been one of the most severe threats to IGBT safety operations. The current mainstream IGBT drivers used in dc breakers primarily choose on-state voltage V_CEsat as the monitor parameter of IGBT desaturation. However, this detection method requires the device first to enter the high-loss desaturation region, which may eventually lead to the thermal breakdown of the IGBT device. This letter reveals a new phenomenon (self-surge current mode) in which the gate voltage V_GE rises prior to IGBT desaturation. This letter proposes a novel detection method that uses V_GE as a desaturation precursor based on comprehensive analyses of this phenomenon. The proposed method enables highly reliable and sensitive detection while having little impact on the IGBT devices’ maximum current performance, preventing the IGBT device from entering the extremely high loss desaturation region. The experimental results in this letter show that compared to traditional V_CE detection, proposed V_GE detection can reduce detection time by more than 80% and IGBT junction temperature rise by more than 75%.