Study and construction of traction control system of EMUs

Since the introduction of Electrical Multiple Units (EMUs) to China, traction control technology has become one of the study hotspots. The traction control system of EMUs consists of a traction converter system and a Traction Control Unit (TCU). The traction converter system is composed of a transformer, a four-quadrant pulse rectifier, intermediate DC link, rheostatic chopper, a three phase half bridge inverter and an induction motor. The traction control unit is the brain of the whole system. It controls rectifier, chopper and inverter according to the signals which come from sensors and orders which come from the Center Control Unit (CCU). By reference to the voltage range of the traction system in CRH5, the traction and control system is constructed. And TCU is designed to have hierarchic structure. Then the whole system is simulated. In the system the rectifier is controlled by the theory of transient current control with SPWM (Sinusoidal Pulse Width Modulation) technology. The chopper is used to control filter voltage as a soft crowbar. In the inverter the indirect rotor flux oriented vector control theory with current hysteretic band PWM strategy is adopted. Interface which refers to driver control desk is completed with GUI (Graph User Interface) tool in Matlab. Through the interface EMUs' speed and traction effort are set and the real speed is shown. Both traction control and constant speed control of EMUs are simulated based. The results present that the system has the advantage of good dynamic and steady state performance. And the system is useful for study the performance of the whole system with various control strategies.