Application Of The Pulse Rectifer In Traction Converter

The scope of Pulse rectifier's application areas has become more extensive for the advantage of bidirectional power flow,adjustable power factor and reducing the grid's"pollution",etc. Therefore, the research of application of pulse rectifier in various fields is becoming more important, the pulse rectifier of CRH5 is used as the research object of this dissertation.For the pulse rectifier of CRH5, structure and working principle of pulse rectifier are discribed,and it gives the commonly used mathematical model of pulse rectifier. A variety of current control strategies were studied, including the indirect current control, hysteresis current control, constant switching frequency control, predictive current control and transient current control. The principles of the various control strategies and implementation have been described,and the transient current control was chosen as the control program. A theoretical analysis on the SPWM (Sinusoidal Pulse Width Modulation) principles of modulation and MSPWM(Multiple-SPWM) technology was made.Above these research,the calculation of the key circuit parameters of pulse rectifier was given.The steady-state characteristics and dynamic performance of the rectifier are obtained through executing the simulation by use of Matlab/Simulink.The simulation results show that the pulse rectifier can achieve close to unity power factor and constant output voltage in both traction condition and regenerative braking condition,and to achieve traction and regenerative braking condition smoothly switching between each other and bidirectional power flow.Through theoretical analysis and modeling simulation approach to verify the design of the rectifier in the primary circuit, the circuit parameters, control strategy, modulation methods, and the reasonableness of the pulse rectifier establish the theoretical basis for a wider range of applications in the field.