Reliable Gate Driving of SiC MOSFETs With Crosstalk Voltage Elimination and Two-Step Short-Circuit Protection
Chengmin Li, Jing Sheng, Dražen Dujić
Abstract
The overstress of the negative gate-source voltage of SiC MOSFET, even in a short period of time, could cause the threshold voltage drift of the device, resulting in increased on-state resistance. In this article, we propose an integrated gate driver to specially limit the peak negative gate voltage of SiC MOSFETs introduced by the crosstalk phenomenon and the reliable short-circuit protection. A simple auxiliary branch with bidirectional blocking capability is adopted in crosstalk voltage suppression and the negative peak voltage of the gate, introduced by common source inductor, is eliminated by the high impedance gate driving loop. Furthermore, the auxiliary circuit is reused to assist a two-step short-circuit protection of the device by identifying dc-link shoot-through current on the stray inductor. By rapidly reducing the gate-source voltage to a lower value when short-circuit happens, the short-circuit withstanding time of the device is prolonged, enabling a longer allowable detection time to confirm the fault event accurately. The proposed method comprehensively integrates the crosstalk voltage suppression and short-circuit protection together and is verified by the experiments.