| As the third generation of power semiconductor devices,SiC MOSFET has better endurance for high-temperature and high-voltage and has faster switching speed and lower switching loss.There are more and more research and application about SiC MOSFET.Using SiC MOSFET insdead of Si IGBT can reduce switching loss and at the same time increase switch frequency.This can improve the power density of the whole power electronic equipment system.The driver circuit is crucial for the application of switching devices.Due to the different properties of SiC MOSFET and commonly used silicon devices,it is necessary to study SiC MOSFET’s driver circuit,including the important short circuit protection.In addition,oscillations are easy to occur during fast switching process.Oscillations threaten the safe application of SiC MOSFET so they need to be studied and analyzed.This paper designed a driver circuit for SiC MOSFET using discrete devices according to the properties.The driver has several functions such as isolation,buffer,short circuit protection,under-voltage protection,dead time and interlock.The driver has dual outputs and can be used to drive the half-bridge module.The functions and performance of the driver are tested by experiments.Desaturation detection is the most commonly used short circuit protection for IGBT.It’s simple and reliable.When it’s used for SiC MOSFET we can detect the drain-source voltage.Unlike IGBT,SiC MOSFET almost won’t show the desaturation phenomenon.And SiC MOSFET’s short circuit withstand capacity is weaker.So in this paper,the desaturation detection circuit is analyzed in detail.The protection value and blanking time calculation are listed.The analysis and experiment show that the parameter setting method can affect the detection delay.It needs a proper parameter set to minimize delay time when it’s used for SiC MOSFET.Several oscillations occurred during the switching process and affected the test and application of the device.In this paper,the oscillations were analyzed,including the high frequency oscillation appeared in both the switching on and switching off process,the lower frequency oscillation appeared in the switching on process and the high frequency oscillation appeared in the switching off process.The factors and causes of the oscillations are explained,which can help to the improve of oscillations to some extent. |
