Research On Traction Cotrolling System Of Low Speed Maglev Train

Maglev train is a new type of vehicle on railway track. It is drived by linear motor. Levitated over the rails, the body of the train does not touch the ground, thus there exists no friction. Compared with the ordinary trains, it is easier to be maintained, so many researches on the maglev train have been conducted around the world. Nowadays, the technology of the maglev train in China is developing quickly, low speed maglev train enjoys the priortiy in railway transportation between cities and has a lot of advantages, such as lower noise in operation and less difficulty in construction. This thesis fouses on the controlling method of single-sided linear induction motor (SLIM) and the controlling system for the vehicle traction employed in the maglev train. As using SLIM to propel the maglev train is one of the key technologies of low speed maglev train, the present study has practical siginificance in promoting the development and the application of the technology of the maglev train.Firstly, the analysis of SLIM used in the maglev train is conducted and SLIM equivalent circuit model with end effect is established. Based on the model drived by constant current, the thesis carries out the three-dimensional analysis on SLIM's air-gap flux, as a result, the analytic expressions of the SLIM's thrust force and levitation force are derived. Then the thesis discusses the characteristics of the maglev train, whose drive force is SLIM, and its requirements for the traction system. By means of the theoretical analysis and simulation of SLIM's forces, the author reaches the conclusion that in theory controlling method with constant current and constant slip frequency can provide thrust force satisfactorily and at the same time avoid disturbance, generated by excessive fluctuation of normal force, on the levitation system. Because the thrust force is supplied by the drive units distributed in different parts of the train, in order to balance power among these units, the tractioncontrolling system should coodinate thrust forces from these units. According to the characteristics discussed above, the controlling system design of the maglev train traction is offered hi this paper. Finally, an experiment is worked out to testify the design. The results show that the above-metioned controlling method can realize the operation of SLIM with a constant thrust force, that normal force does not fluctuate greatly at the specified speed and that the controlling system of the tranction operates regularly, meeting the requirements of the design.