Research Of The Traction Converter Used In CRH5

With the rapid development of our economy, it is inevitable to improve the speed of the train in our country. In order to accelerate the tempo of the high-speed railway, the ministry of railways absorbed in EMU (electrical multiple units) from the developed country. CRH5 is one of the first introduced EMU. So it is advantage to promote the steps of high-speed EMU sinicization if we detailedly research the structure and characteristic of the CRH5.The traction converter is main part of the traction system of CRH5. It is used as the research object of this dissertation. The dissertation tightly surrounds the traction converter used in CRH5. Through combining actual measurement and theoretical derivation, the rationality of the parameters applied in CRH5's traction converter is proved. In the thesis, the main circuit with single-phase two-level structure, SPWM modulation strategy, transient current control strategy and phase-shift carrier wave technology which are applied in the rectifier of the traction converter are analysed in detail. The steady-state characteristics and dynamic performance of the rectifier are obtained through executing the simulation by use of Matlab/Simulink. At the same time, the main circuit with two-level structure, asynchronous modulation strategy, subsection synchronous modulation strategy, pulse precalculated modulation strategy, square wave modulation strategy and rotor field orientation vector control strategy which are used in the inverter of the traction converter are studied deeply. Based on the analysis of theory, simulation models are built by use of Matlab/Simulink and the traction characteristics of the motor are verified.The simulation results show that the rectifier of the traction converter can achieve close to unity power factor and constant output voltage in traction condition. As the rotor speed of the traction motor increase, the characteristics, such as constant output torque, constant output magnetic flux and a small quantity THD of the motor's input current, are ensured through adjusting the frequency and amplitude of the traction inverter's output voltage. And the constant torque performance of the traction motor is satisfied.Basing on the thorough research of CRH5's traction converter, the dissertation combines the theoretic analysis method and modeling simulation method. The rationality of the main circuit, basis parameters, modulation strategy and control strategy of CRH5's traction converter are proved,which establish the theoretical basis for the total domestic manufacture of high-speed EMU.