Application Research Of Auxiliary Inverter Based On SiC MOSFET

With the rapid development of the tram,the power density,reliability and efficiency of the auxiliary converter are higher than those of the tramcar,which is an important part of the urban rail transit vehicle.At present,the circuit topology and control method of vehicle auxiliary converter have been developed,and the traditional auxiliary converter based on silicon device(IGBT)is difficult to improve the above performance index.In this paper,the application of SiC MOSFETs in the auxiliary converter of urban rail transit is studied.The optimization design of the passive components is accomplished.The device loss model of the main circuit topology is designed.A SiC MOSFET driver circuit is designed and verified.Characteristics of the realization of SiC MOSFET in the auxiliary converter in the application.In this paper,the device characteristics of SiC MOSFETs are analyzed.The influence of parasitic parameters on switching speed,switching loss and voltage and current waveforms during switching process of SiC MOSFET is analyzed.Secondly,based on the analysis of the topology of the original Si-based IGBT auxiliary converter,the switching frequency of the system is improved by SiC MOSFET,and the parameters of the transformer and the parameters of the filter are optimized to improve the power density of the auxiliary converter.Then,for the optimized auxiliary converter,combined with the system operating conditions and control strategy,the main circuit power device loss analysis and calculation,and to study the loss model,as the basis for thermal simulation.Finally,the design idea of SiC MOSFET driving circuit is expounded in detail.Based on this,the SiC MOSFET driving circuit can be designed to assist the converter,the double pulse test platform is built,and the performance of the driving circuit is tested.The switching characteristics of SiC MOSFETs and Si IGBTs are presented to illustrate the performance advantages of SiC MOSFETs.