Design of a Gate-Driving Cell for Enabling Extended SiC MOSFET Voltage Blocking

Abstract

A series connection of SiC MOSFETs for kV blocking capability can enable more design flexibility in modular multi-level converters as well as other topologies. In this paper, a novel gate driver circuit capable of driving series-connected SiC MOSFETs for high voltage applications is proposed. The primary advantage of the proposed design is that a single gate driver was used to switch all the series devices. The circuit used switching capacitors to sequentially charge and discharge device gate capacitances during switching and enable a negative turn-off voltage to avoid device coupling from Miller-capacitive feedback effects. With the proposed gate driver design and appropriate component values selection, avalanche breakdown due to voltage divergence during switching transients could be avoided with only a minor imbalance in the top device. Simulations and experimental measurements showed that the zero-current turn-off transition of all switches was achieved, and this approved the validity of the design.

Keywords

• series SiC MOSFET
• driving circuit
• high voltage