Research and Simulation on Synchronous Traction System of High-Speed Train
|Course||Control Theory and Control Engineering|
|Keywords||High-speed train traction system traction converter traction control strategy permanent magnet synchronous motor(PMSM) direct torque control(DTC) synchronized control algorithm|
High-speed train traction system is not only the power source of a train, but also the key structure to ensure fast running and stable operation of train. The main circuit includes traction transformer, single-phase three-level rectifier, middle DC link, three-level inverter and traction motor.The components and functions of high-speed train traction system is described first, with the permanent magnet synchronous motor instead of the traditional three-phase asynchronous motors as traction motors, high-speed train traction system simulation model is built using Matlab/Simulink, to study and compare the control strategies and control algorithms of traction converter with the simulation results.SPWM modulation, and forecast current control strategy is adopted in single-phase three-level rectifier. The direct torque control system is used for three-level inverter to drive the permanent magnet synchronous motor. According to CRH3 EMU traction and brake trait curves, the system can simulate traction, inertia, brake and other operating conditions of a train to achieve the stable operation at different speeds. The simulation results indicate that the DC voltage is steady, the speed changes smoothly when the speed command changes, the system has good dynamic and static performance. In traction condition, the use of direct torque control makes the output torque of traction motor torque command tracking well, constant torque operation is adopted at low speed. In constant speed condition, EMU speed is according to the given speed command and the speed limit of current region. The control command changes smoothly, using the hysteresis control strategy, to avoid the torque and speed impulsion during the switching between the various operating conditions.After the stability control of a single traction motor, a synchronized control algorithm for multi-motor system which bases on the adjacent coupling error is adopted in a basic power unit which contains 4 traction motors. The results of the comparison of other synchronous control algorithms show that this synchronization control algorithm has good stability and fast convergence rate.