A gate drive circuit for Normally-On SiC JFETs with self-protection functions against overcurrent and shoot-through fault conditions

Abstract

Normally-On Silicon Carbide (SiC) JFETs are considered promising switching semiconductor devices due to their capability to operate in high voltages, frequencies and temperatures. However, an efficient driving and protection scheme is required to fully exploit their potential for use in power converters. In this paper, a proposed self-protection topology is integrated into a fast switching ac-coupled gate drive to minimize fault detection time for the prevention of overcurrent and shoot-through faults caused by the normally-on behavior of the device. The developed topology uses the desaturation principle through a sensing diode to detect drain-source voltage under overcurrent condition. A configuration to keep the device in the off-switching state in case of gate drive power supply failure is also included. The gate drive itself applies forward bias to achieve lower on-state resistance, while design considerations are described in order to achieve fast switching times. A double pulse tester set-up with a phase-leg configuration is used to experimentally verify the performance of the proposed protection schemes under various fault conditions as well as measure switching losses. The standalone nature and easy parameterization of the proposed driving and protection topology makes it suitable for use in any power converter built with normally-On SiC JFETs.