Gate Driver Design for 1.2 kV SiC Module with PCB Integrated Rogowski Coil Protection Circuit

Wide band-gap materials, e.g., Silicon Carbide (SiC), allow the realization of power semiconductor with superior performance with respect to the traditional Si-based counterparts. On the other hand they require more stringent short-circuit or over-current clearing time to safeguard the device lifetime. This paper focuses on the analysis, design guidelines and practical implementation of a gate drive circuit incorporating fast short-circuit/over-current protection $(\lt 1 \mu \mathrm{s})$ based on the device di/dt measurement through PCB-based auxiliary Rogowski coils. The target power module is a industry standard 62mm packaged 1.2kV SiC MOSFET half-bridge. The gate driver protection features are experimentally tested and the target time for the short circuit clearing was satisfied, with the gate driver effectively turning off the switches within 400 ns during a short-circuit test.

I. Introduction

The utilization of wide band-gap power switches in the power electronics industry has considerably contributed to improvements on power conversion efficiency and power density [1]. Lower switching times and resistive on-state behavior, higher breakdown voltage and operating temperature are the most advantageous parameters that wide band-gap materials (WBG) based power semiconductors brings over the traditional silicon based ones [2] –[6]. On the other hand, new fundamental requirements emerged on the design of the gate drivers. Firstly, the short-circuit capability of Silicon Carbide (SiC) based devices is much lower than the one of the traditional silicon devices, therefore faults need to be identified and cleared within a few microseconds [2], [7], [8]. The short-circuit withstanding time and ratio between the maximum current and rated current of commercial 1.2kV Si IGBTs and SiC MOSFETs from [9] is shown in Fig. 1. As possible to notice, SiC MOSFET show higher short circuit currents, up to eight times the nominal current, and can withstand the fault for far less time than the Si IGBTs, up to instead of .