| With the development of power electronic technology,power electronic equipment has been widely used in medical devices,industrial manufacturing and consumer industries,which is of great significance to the improvement of national economic level.Compared with the traditional silicon-based power devices,Silicon Carbide Based Metal-Oxide-Semiconductor Field-Effect Transistor(SiC MOSFET)has the characteristics of lower switching loss,higher switching speed and operating temperature.Therefore,the application of SiC MOSFET improves the power density and efficiency of power electronic converter.However,the high switching frequency and switching speed make SiC MOSFET very sensitive to parasitic parameters,bringing electromagnetic interference and reliability problems,affecting the safe operation of the system.Because the junction temperature change of SiC MOSFET will change its switching process,and then affect the electromagnetic interference characteristics of the system where the device is located and the safe operation of the surrounding equipment.At the same time,because SiC MOSFET has low threshold voltage and maximum allowable negative gate voltage,crosstalk is easy to be triggered.With the increasingly stringent electromagnetic compatibility standards,a better understanding of the electromagnetic interference characteristics in the system is of great significance to guide the design of related products.In this paper,the switching characteristics of SiC MOSFET module are studied,and the conduction interference characteristics and crosstalk peak prediction of SiC MOSFET are studied through theoretical and experimental analysis.The main research contents are as follows:1.Firstly,the physical structure,working principle and basic characteristics of SiC MOSFET are introduced.Then,the switching process of SiC MOSFET considering the influence of parasitic inductance is analyzed in detail by using the switching equivalent circuit under inductive load,and the voltage and current change rates of each stage are obtained.Finally,the generation mechanism of conducted interference and crosstalk is briefly introduced.2.The effect of temperature on the conducted interference characteristics of SiC MOSFET is studied.Taking the buck converter composed of SiC MOSFET as the research object,by analyzing the temperature variation characteristics of the conducted electromagnetic interference signals during the SiC MOSFET switching process,it is shown that the temperature dependence of the common mode interference sources during the turn-on and turn-off process are the same,while the temperature dependence of the differential mode interference source during the turn-on process is higher than that during the turn-off process.On this basis,combined with the coupling paths of conducted electromagnetic interference in the buck converter system,the conclusion that the differential mode interference in the system increases and the common mode interference almost remains unchanged with the increase of temperature is obtained.The conducted electromagnetic interference test platform is built in the electromagnetic shielding room.The experimental results show that the differential mode interference in the system has a positive temperature dependence and the dependence decreases with the increase of load current;the common mode interference is almost unaffected by temperature.3.A crosstalk peak prediction algorithm for non-Kelvin packaged SiC MOSFET considering the influence of parasitic inductance is proposed.The half-bridge circuit composed of To-247-3 package SiC MOSFET is studied.Firstly,the mathematical model of crosstalk voltages in each stage are analyzed,and the differential expressions of crosstalk voltage are derived;Secondly,the prediction algorithm of crosstalk peak is proposed,and the mathematical models of the parameters required to predict the crosstalk peak are established;Finally,an experimental platform is built to verify the correctness of the theory and the effectiveness of the algorithm. |
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