Research On Permanent Magnet Synchronous Traction Motor Control System Of High-Speed Train

Traction motor is the origin of power for the high-speed train, in order to adapt the development of railway system, at present the high-performance AC speed-adjusting technology is applied in the train’s electric traction, therefore the vector control method and the direct torque control method are regarded as the first choice in the traction motor system. The robustness of traction motor system can be improved as far as possible and the cost of the system should be decreased at the same time if sensorless control technology is added into the system. At present, the critical problem of traction motor system which should be solved is the real- time identification about restarting with unkwon speed, the detecting of slip and anti-slip control and the evaluation for sensorless operation, etc.Firstly, the dissertation sets up a mathematical model of Permanent Magnet Synchronous Motor(PMSM) to discuss Direct Torque Control(DTC) strategy of electric traction and to research the condition of PMSM traction during traction acceleration or short-time loss of power supply. Secondly, the dissertation makes use of sliding mode observer to further improve the control system of PMSM for high-speed trains, and thus to make the control system work without the transducer. The electr ic traction often needs to work on the coasting condition, after that it goes back to work again immediately without reduction of speed, at the same time the speed and location of electric traction need to be precisely estimated during the whole process. In order to solve the problem that the inability to estimate the performance of electric traction during the short-term loss of power condition, the research makes use of short-circuit current vector method to carry out twice short circuit in the electric traction, and thus the research makes use of the short-circuit current value to estimate the rotation rate and location for the electric traction when it goes back to work immediately again.In order to research the control system of slip detecting and anti-slip control for high-speed train’s Permanent-Magnet Synchronous Motor(PMSM), the research preforms the simulation experiment that is based on MATLAB/Simulink platform, which makes the high-speed train’s model to simulate its dynamics. And the same time, the study uses load torque identificaiton system to preform an idle experiment, which means the load torque of electric traction decreases because the friction between wheels and tracks decrease when the wheels start to idle. The experiment may prove that the differential value of load torque has a great change. The dissertation makes use of the following test methods to estimate new electric traction system. These methods are evaluating the electrical quantities time-constant, testing current voltage of electric traction, the model of load torque identification system and the system of identifying idle. The research proves that the load torque identificaiton system is more reliable and faster.