Research On Electromagnetic Interference Mechanism Of Traction Converter

With the rapid development of modern power electronic technique,the traction converter system is gradually developing in the direction of high frequency,high capacity and high power,and it has been widely used in the rail transit industry.The electromagnetic interference generated by it will not only reduce its own reliability and performance,but also affect the normal operation of the surrounding equipment.Therefore,the research on the electromagnetic interference mechanism of the traction converter has theoretical significance and engineering value for solving the electromagnetic compatibility problem.This paper takes the subway train traction converter as the research object.Firstly,it introduces the related concepts and development history of electromagnetic compatibility,and the research status of traction converter electromagnetic compatibility at home and abroad.Then the basic working principle of traction converter is analyzed.Conducted interference analysis of a subway train traction converter is carried out to determine its interference source and propagation path,point out that the change rate of voltage and current caused by the IGBT switch is the main source of conducted interference.Based on the theoretical analysis of the key components such as the IGBT,heat sink,three-phase output cables and the filter in the traction converter,as to the difficulties of how to quickly and accurately obtain the high-frequency equivalent parameters of the converter components,the combination of software simulation and theoretical calculation is used to extract the parasitic capacitance between the IGBT and the heat sink,the high-frequency equivalent parameters of the cables,the high frequency equivalent parameters of reactor and supporting capacitor.The high-frequency electrical model of traction converter for conduction interference simulation is established by using Simplorer,Matlab and Q3D software.In order to deeply study the conduction interference mechanism of traction converter,the time domain and frequency domain characteristics of common mode current are analyzed,and the influence of various spurious parameters on conducted interference is analyzed,and the previous theoretical analysis is verified.Finally,it is pointed out that the common mode interference of traction converter can be suppressed from the common mode filter and buffer circuit of the IGBT.The research content of this paper can not only provide theoretical guidance for electromagnetic compatibility design and rectification of the traction converter.Some new methods of IGBT modeling and component high-frequency parameter extraction are good references for electromagnetic interference simulation of other power electronic equipment.