Modeling And Analysis Of Conducted Electromagnetic Interference In Metro Traction System

As the main component of rail transit,the metro plays an important role in alleviating road traffic pressure,energy saving and emission reduction.As a key component of metro system,the metro traction system usually uses Pulse Width Modulation(PWM)to efficiently control the various operating states of traction motor.However,the switching process of power devices in traction converter will produce high dv/dt and di/dt,which contain rich high-order harmonic,form an electromagnetic interference(EMI)source,and bring severe conduction interference problems to the traction system.This has a serious impact on the reliable and safe operation of the traction system.Therefore,it is urgent to carry out research on the conduction interference problem of metro traction system,so that electromagnetic compatibility(EMC)can be considered in the system design stage,which has important theoretical and engineering value.This thesis models and analyzes the conducted EMI characteristic in the time domain for the metro traction system composed by a 420 kW traction converter.The main research work and results are as follows:(1)For EMI source,a device-level behavioral model of IGBT module that combines datasheet and experimental tests is proposed,which reflects dv/dt and di/dt in the actual switching process and expands the applicable working range.The model is verified by simulation results with experiment results.(2)Aiming at the conduction interference coupling path,finite element simulation and“impedance analyzer – high frequency parameter extraction” methods are used to establish high frequency circuit models for each component of conduction interference path.Based on the research fundamental of conducted EMI mechanism,the conduction interference model of metro traction system is established in simulation platform,and the effectiveness of the model is verified through experiments,then the reasons of simulation errors are analyzed.(3)Based on the idea of “modeling – variable parameter analysis – rules summary”,the influence of traction converter modulation strategy and other parameters on the system conducted interference are studied through simulation,then the influence rules of traction converter parameters on conducted interference are summarized and verified through experiments.The modeling and analysis of conducted electromagnetic interference in metro traction system are studied in this thesis.The conducted interference modeling methods and variable parameter analysis method in the thesis are helpful for the prediction and evaluation of conducted interference level in the traction system design stage,so as to carry out EMC forward design and help the vehicle conduction emission test passes the standard inspection successfully.