| With the fast development of power electronics over the past few decades,it has been adopted in more and more application fields.Si devices are gradually reaching its physical limit,WBG(Wide Band Gap)semiconductor devices such as SiC MOSFET has attracted much attention recently.Compared to silicon devices,SiC MOSFET has superior performance such as higher break-down voltage,lower losses,higher switching frequency,higher junction temperature etc.However,the study of the characteristic of SiC MOSFET is still not sufficient,which limits the application of SiC MOSFET in practical applicationsDue to fast switching speed,high voltage overshoot is generated during turn-off transient,which increases the voltage stress of semiconductor device.A new gate driving method is proposed to limit the voltage overshoot by controlling the di/dt of turn-off transient,compared to traditional gate driving method,the new method can reduce the turn-off loss and turn-off delay besides the di/dt control.Many research works have been carried out to investigate the short-circuit withstand time under different bus voltage of SiC MOSFET,but few are about its short-circuit withstand ability under different gate voltage.In this thesis,short-circuit withstand ability of varies gate voltage under a 600V bus voltage is studied,the short-circuit withstand time increases with the decreasing of gate voltage,and the short circuit peak current decreases at the same time.According to short-circuit ability studied above,a short-circuit protection circuit with soft turn-off ability is proposed,which can reduce voltage overshoot during short-circuit protection effectively. |
