Research On Transient Process Control Of SiC MOSFET

With the rapid development of the social economy,the demand for electrical energy in various sectors of society is getting higher and higher,and the power system requires higher voltage,greater power capacity and higher reliability for power electronic devices.Because of its high voltage,high power,high temperature resistance,and low switching loss,SiC MOSFET has broken through the limitations of silicon-based devices and is gradually gaining popularity in the market.However,SiC MOSFET is very sensitive to parasitic parameters due to the transient high switching process,which can easily cause problems,such as severe voltage and current spikes,switching oscillations,and prominent electromagnetic interference.These problems will seriously threaten the stability and safety of power system equipment operation.Aiming at the problems of SiC MOSFET transient process,this paper establishes an analytical model of the device module based on the double-pulse test method,and conducts theoretical analysis of the switching process of the device.Based on the starting of driving control,a staged driving control method is proposed.By controlling the amplitude of the staged driving voltage and its sustaining time,the change rate of the drain current and the drain-source voltage are reduced to optimize the switching characterization of the device.In the switching power source simulation software LTspice,a simulation model was set up for simulation analysis.A physical test platform was built.using CREE's CAS300M17BM2 SiC MOSFET half-bridge module for experimental verification.For the problem of optimizing the switching characterization of SiC MOSFET by using a staged driving control method,the switching time of the device will be delayed and the loss will increase.This paper analyzes the corresponding loss at the device level and the application level of typical devices in the power system.Through the device-level loss analysis,it will sacrifice part of the switching energy loss,but the switching energy loss is still less than the same voltage-level Si IGBT.In the application of equipment,the application loss of DC/DC converter and STATCOM converter unit that are typical applications in power systems are analyzed.Compared with the conventional parallel RC snubber circuit,the SiC MOSFET using the staged driving control has a lower total loss.