Gate Drive Circuit for Silicon Carbide (SiC) MOSFETs

Abstract

Bridge leg configuration is commonly used in motor control, convertor circuits. However, a spurious pulse is the parasitic characteristic of the configuration. The pulse is dependent on parasitic capacitances and inductance of MOSFET. This pulse causes spurious turn on that may turn on both MOSFET at the same time resulting in a short circuit and broken devices. In high power and frequency, the spurious pulse becomes the dominant factor in the circuit. SiC MOSFET is a wide bandgap device that causes serious spurious pulse in high switching speed and power bridge leg configuration.

The project is to design a gate drive circuit to reduce the effect of the spurious pulse. RDC level shifter and LCR resonant circuit are used to reduce the peak gate-source voltage of MOSFET 2 when the signal is low. A synchronous buck converter was designed for demonstration and shown the circuit's improvement. The circuit can remove the spurious turn on and increase the stability of the circuit.