Charge Pump Gate Drive to Reduce Turn-ON Switching Loss of SiC MOSFETs
Handong Gui, Jingjing Sun, Leon M. Tolbert
Abstract
Turn-on loss is the dominant part of the switching loss for SiC MOSFETs in hard switching. Reducing turn-on loss with conventional voltage source gate drives (VSGs) is difficult because of the limited gate voltage rating and large internal gate resistance of SiC MOSFETs. A charge pump gate drive (CPG) that can reduce the turn-on loss is presented in this article. By precharging the charge-storage capacitor in the gate drive with a charge pump circuit, the gate drive output voltage is pumped up to provide higher gate current during the turn-on transient. As a result, the turn-on time and loss is decreased. Moreover, due to the charge transfer from the charge-storage capacitor to the MOSFET gate capacitance, the pumped output voltage can naturally drop back to a normal value that avoids gate overcharging. The structure of the gate drive is simple, and no additional control is needed. The operation of the proposed CPG is verified with double pulse tests based on SiC MOSFETs. The switching loss of the proposed CPG is reduced by up to 71.7% compared to the conventional VSG at full load condition.