Research On Key Technologies Of SiC Device Modeling And Driving

At present,silicon carbide(SiC)power switching devices have begun to be commercialized.The switching devices represented by SiC Schottky Diode(SBD)and MOSFET are mainly used in AC/AC,DC/DC power electronic devices,which can significantly improve power density and efficiency.However,silicon-based power devices are still used in the modeling,driving and protection of SiC power switching devices.With the increase of switching frequency of SiC power switching devices,the influence of parasitic parameters on driving circuit can not be neglected.There are two main effects: one is gate crosstalk,which will cause the problem of bridge arm through;the other is the overvoltage of the devices,which will cause the Breakdown of devices,these two problems limit the application of devices in high frequency and high voltage.In the aspect of modeling,besides considering parasitic parameters,we should also consider that SiC power switching devices are at the stage of development.On the one hand,devices update rapidly,on the other hand,there are individual differences in devices,which also brings challenges to device modeling.In this paper,on the basis of summarizing the shortcomings of current diode modeling and considering the influence of parasitic parameters,a fast modeling method for circuit designers is proposed and compared with the actual test data.On the other hand,because SiC MOSFET driver is different from Si-based driver,gate negative voltage driver is often used to suppress crosstalk,but how to choose the negative voltage is not reasonable.On the basis of this,a method to determine the negative gate voltage of SiC MOSFET is proposed.Then,based on summarizing the shortcomings of the existing drive schemes for SiC MOSFET,a new type of SiC MOSFET half-bridge structure crosstalk suppression circuit is proposed,which is finally verified by software LTspice.The main research contents are as follows:(1)Through the research and analysis of the existing SBD modeling methods,a fast modeling method is proposed based on the practical application requirements.Finally,the SiC SBD discrete components are tested and validated,and the results are in agreement with each other to meet the design requirements.(2)From the point of view of the influence of driving gate negative voltage on the overvoltage of SiC MOSFET,a method to determine the driving gate negative voltage is proposed through theoretical analysis.This method can locate the corresponding gate negative voltage at the minimum overvoltage.(3)Aiming at the crosstalk problem of SiC MOSFET,a novel bridge structure crosstalk suppression circuit of SiC MOSFET is proposed.The circuit can effectively suppress grid forward crosstalk and improve the switching speed of devices.