Research On The Analysis And Suppression Methods For Crosstalk Of SiC MOSFET Bridge Circuit

Silicon carbide (SiC) power devices have been widely application with its fast switching speed, low specific on-resistance, highly junction operating temperature. However, with the increasing of switching frequency, it’s more obvious that the effect of parasitic parameters on the switching characteristics of devices, resulting in the increase of switching losses, higher voltage and current stress. The stability of the converter is affected, and the crosstalk in high frequency bridge circuit is more serious. In view of the crosstalk problem of SiC MOSFET bridge circuit, the thesis analyzes the effect of parasitic parameters on the gate-source voltage of SiC MOSFET, to make theoretical guidance for the hardware circuit design and selection of devices. A novel SiC MOSFET driving ciruit for suppressing the crosstalk is designed on the basis of theoretical anslysis.The thesis analyzes the effect of the parasitic parameters and appropriate extraction method, and fits the curve of related parameters by using mathematical expressions. Then, the mathematical model of SiC MOSFET switching process is established using the synchronous Buck converter, and the influence of parasitic parameters on the switching characterisitics is considered. The equivalent circuit of the synchronous Buck converter is established in different stages, and the mathematic expressions of relevant variables are soluted by using the equation. Then, the thesis researches the generating process of crosstalk in bridge circuit. The model is used for analyzing the effect of parasitic parameters on the gate-source voltage of SiC MOSFET in the switching transient. The effect of parasitic parameters is verified through simulation and experiment. Finally, the thesis introduces the methods for suppressing the crosstalk and their characterisitics. A novel SiC MOSFET driving circuit is designed, and the performance of the driving circuit is verified through simulation and experiment.The mathematical model can accurately describe the switching process of SiC MOSFET. And the model is used for analyzing the effect of parasitic parameters on the gate-source voltage of SiC MOSFET in the switching transient, providing theoretical guidance for PCB layout and device packaging. The novel SiC MOSFET driving circuit can effectively suppress the gate-soure voltage of SiC MOSFET caused by crosstalk.