Experimental study of an EMI reduction gate-driver technique for turn-off transition of 1.7 kV SiC MOSFET

This paper proposes a novel self-controlled SiC MOSFET gate driver circuit. This new gate driver (GD) proposes a dynamic gate-bias modification thanks to a passive feedback of the drain or source current to control the EMI during turn-off switching transition. A Rogowski coil integrated into the terminals of the SiC MOSFET provides the feedback to modify the gate voltage profile. During turn-off, this circuit increases the voltage level of gate and consequently the gate current. This approach has a positive effect on the EMI behavior of converters without harmful effect on converter efficiency compared to the conventional method which consists in increasing the gate resistance. Moreover, with this approach, the gate driver design remains without modification (except the connection to the Rogowski coil) and there is no effect on turn-on transition of the SiC MOSFET. The proposed method is designed and developed for a 1.7kV SiC MOSFET and has been validated experimentally in an inductive double-pulse test platform. The proposed gate driver moderates the switching speed and is validated experimentally up to 1.2 kV 200A with the 1.7kV SiC MOSFET by reducing the common-mode current of turn-off transition.

1. Introduction

Wide bandgap devices require less gate charge to switch on or off and have overall better figures of merit than conventional Si devices [2]. They can be then used to improve the efficiency or density of power converters and power transistors based on GaN or SiC technologies are expected to represent a growing market in the next few years considering their decreasing price and excellent characteristics [1]. Therefore, research in these new technologies is of a great interest in the power electronic domain.