This paper investigates the gate-driver design challenges encountered due to the fast switching of wide band-gap semiconductors (here, SiC MOSFETs) in the half-bridge configuration. It discusses precisely the common-mode current generated by fast switching passing through gate-driver, which leads to drivingvoltage perturbations and disturbs the correct triggering of switches. This phenomenon is described here as self-disturbance and the experimental study shows that it is exacerbated with SiC MOSFETs, when compared with Si IGBTs. The solution proposed in this article is to block the generated noise linked to self-disturbance phenomenon by placing a common-mode choke into the gate path. The proposed solution is compared with the classical active Miller-clamp protection solution. The experimental results from 1.7kV, 300A SiC MOSFET validate the solution. The solution proposed in this work allows to keep the MOSFET gate-voltage perturbation lower than the MOSFET threshold voltage while it does not increase the switching losses. Experimental results show that by implementing the proposed solution, it is possible to reduce the input common-mode current through the gate driver by up to 20%.

Hadiseh GERAMIRAD, Florent MOREL, Bruno LEFEBVRE, Christian VOLLAIRE, Arnaud BREARD

Presented at PCIM Europe 2020 Digital Days