Real-time Optimization of IGBT/Diode Cell Switching under Active Voltage Control

A combined digital and analogue approach is introduced to establish a dynamic Active Voltage Controller (AVC) for controlling an insulated gate bipolar transistor (IGBT), suitable for series connection of devices. In the AVC, the reference voltage dictates the switching trajectory of active voltage controlled IGBTs via a feedback loop. By means of employing adaptive and self-timing control methods to adjust the reference voltage profile according to the transient states on the power side, this new controller has achieved real-time optimization of the IGBT switching with lowest possible power losses. In particular, this new AVC has provided an efficient and flexible solution to addressing the diode reverse recovery and the IGBT-diode commutation during IGBT switch-on operation. The commonly seen voltage overshoot and extra power loss associated with diode reverse recovery voltage are greatly reduced in the new AVC. The optimal switching performance in experiments for both a single IGBT and IGBTs connected in series is given in this paper. This is an effective solution to IGBT control without snubber networks and shows the effectiveness of concurrent optimization of devices and circuits.