Active Variable Gate Drive for Suppressing IGBT Collector Current Overshoot

An active variable gate drive (AVGD) method based on FPGA and comparators for high-power IGBT modules is proposed in this paper to suppress IGBT collector current overshoot. Since conventional way that using larger gate resistor will limit the switching speed and increase switching loss, a variable gate drive is presented to change the gate resistor value in different stages during turn-on process which are identified more accurately by an innovative stage detection method using comparator feedbacks under the control of FPGA. The control response is ultra-fast that IGBT gate charging speed will slow down in time during the specific current rising process. Consequently, compared to conventional way, the current overshoot can be effectively suppressed and switching loss can be reduced as well. In order to verify the feasibility of the proposed AVGD method, a double-pulse experiment is conducted on a 1200V/400A IGBT module finally.