Research On The Electromagnetic Compatibility Of Traction System Of Dual-Current System Train

With the rapid development of China's rail transportation,the connection problem between intercity railway and urban railway appears gradually.For realizing operation seamlessly under different power feeding modes(i.e.different current systems),the multi-current system train needs to be developed.In different feeding modes,the electromagnetic disturbances generated by the traction converter system of the train cannot be ignored and the electromagnetic compatibility between the train and the ground signaling devices should be taken into consideration.Especially in the AC-DC-AC traction mode,the converter is one of the main electromagnetic disturbance sources,and its influence on the electromagnetic environment around the train is essential.In this thesis,the traction converter system of the dual current system Intercity Multiple Units is taken as the research object and its electromagnetic compatibility is studied,simulated and analyzed.The research mainly includes the following aspects:Firstly,the topology structure of the traction converter system is analyzed,both of the rectifier and inverter are described in detail.Based on the equivalent switching principle,the energy flowing and the state changes in the rectifier and inverter during their working process are discussed.The composition and function of intermediate DC link are also introduced.By using finite element method and two-dimensional transient magnetic field analysis theory,the model of 275kW asynchronous traction motor is constructed and simulated in Maxwell software environment.Secondly,focusing on the principle of pulse width modulation(PWM),the traditional sine PWM and space vector PWM methods and their respective characteristics are studied in details.For the rectifier circuit with double connection topology,the transient direct current control is adopted,and the main circuit and control system models are built in Ansys Simplorer and Matlab Simulink respectively.The SPWM and the SVPWM inverter circuit models are built in the Simplorer environment,then combining with the FEM model of motor which mentioned in previous paragraph,the field-circuit coupling simulations of motor and controlled inverter based on two kinds of PWM(SPWM and SVPWM)are implemented.Then,according to the above models,the simulation results of rectifier,inverter and traction motor are obtained.The voltage and current waveforms in simulation are analyzed in time domain and frequency domain,the electromagnetic disturbance caused by PWM operation or common mode disturbance are discussed.According to the motor's FEM simulation results,the influence of harmonics on motor performance is analyzed.In addition,based on the above simulation models,a system level model of traction converter system is built,and the electromagnetic compatibility analysis is carried out from two aspects of conducted disturbance and radiated disturbance.Finally,by measuring the common mode disturbance current on the input cable of a real traction motor,the common mode disturbance current caused by the inverter-motor subsystem is discussed.At the same time,the magnetic field around the motor is measured.Comparing the tested results with the simulation results,the practicability of the simulation model is verified.