Active gate driver for fast switching and cross-talk suppression of SiC devices in a phase-leg configuration

This paper presents an active gate driver for Silicon Carbide (SiC) devices to fully utilize their potentials of high switching-speed capability in a phase-leg configuration. Based on the SiC device´s intrinsic properties, a gate assist circuit consisting of two auxiliary transistors with two diodes is introduced to actively control the gate voltages and gate loop impedances of both devices in a phase-leg during different switching transients. Compared to a conventional gate driver, the proposed circuit has the capability of increasing the switching speed of the phase-leg power devices, suppressing the cross-talk to below device limits. Based on CREE´s 2nd generation 1200-V SiC MOSFETs, the test results demonstrate the effectiveness of this active gate driver under various operating conditions. The switching time decreases by up to 28% during turn-on and 50% during turn-off in the prototype circuit, resulting in up to 31% reduction in switching energy loss. In addition, spurious gate voltages induced by cross-talk are limited within the required range.