Analysis Of Electromagnetic Compatibility Of Traction Converter

Traction converter, as a switching device of high power voltage and current, plays an extremely important role in the whole system of electric locomotive, at the same time,traction converter is the main electromagnetic disturbance source of the electric locomotive, anda series of electromagnetic compatibility problems caused by ithave been paid more and more attention.The thesistakes the traction converter of the CRH380AL type EMU as the research object, and analyzes the electromagnetic compatibility of the traction converter system.Firstly, the thesis introduces the whole structure and basic principles of two point and three point traction converter. According to the theory of switch function, the thesis also analyses the operation principle, operation mode and circuit topology of four quadrant pulse rectifier, intermediate energy storage link and inverter, and the simulation module of rectifier and inverter is built by using ANSYS Simplorer.Secondly, the thesis describes the basic principles of pulse width modulation, including the signal generation mechanism of sinusoidal pulse width modulation and the space vector pulse width modulation. For the rectifier and inverter part take different pulse width modulation mode, combines with converter control theory, and establishes the rectifier and the inverter control system simulation module, realizes the control mode simulation of the sine pulse width modulation and the space vector pulse width modulation.Then, the simulation model of rectifier and inverter of traction converter system were built on the ANSYS Simplorer simulation platform, after the simulation, the thesis analyses the characteristics of voltage and current waveformin time domain and frequency domain, especially the harmonics and the Common mode electromagnetic disturbance characteristics. In order to analyze the conduction disturbance of the motor input, the thesis built the simulation model of traction model by using ANSYS finite element simulation software. The simulation results show that the value of parasitic capacitance should be reduced to the minimum, and the inhibitory effect of the high order harmonics of the output is very obvious by adding the filter circuit or filter at the output side.Finally, the thesis carries out a practical test on the traction converter device. By measuring the magnetic field and harmonic current around the traction system under different conditions, the thesis gets the conclusion that In the whole process of the operation, the obvious disturbance signals exist in the locomotive traction transformer within a frequency range over 2000-3000Hz, which may constitute interferences to the track circuit block section of the carrier frequency that is 2000HZ、2300Hz and 2600Hz.