Simulation Of Linear Induction Motor Traction System And Calculation Of Electromagnetism Force In Maglev Vehicles

As a novel environment-protected vehicle, the middle and low speed maglev train has a large climbing gradient, small swerving radius, low noise, no pollution and can be compatible with any circumstances. It is the most competitive in the future city traffic. An important part of the train traction system is linear induction motor (LIM), whose characters have a great impact on the performance and economy index of the train. Research on LIM thrust, efficiency and control scheme is made to conclude some measures of improving LIM performance. And the electromagnetism resistance in maglev traffic is discussed in order to see the interaction mechanism of electromagnetism.Firstly, the characters of LIM are analyzed by simulation. Influence of end effect on air gap magnetic field, thrust is dwelt on, and the relationship between end effect force and structure parameters of motor is stated. Change of LIM efficiency, power factor, thrust with the different air gap, secondary structure, velocity is calculated by finite element method. The simulation results show that the power factor and efficiency of LIM are much lower than that of rotary induction motor due to end effect and big air gap of LIM. End effect force has a great influence on the thrust of LIM. The performance of LIM can be improved with the proper secondary structure, small air gap, big goodness factor or heavy load. And it can be controlled running at a rating slip, when its efficiency is the highest.Then,simulation model of LIM vector control system is constructed, which is proved accurate by simulation results under different speed and different load. And it is concluded that LIM efficiency is lower under light load or low speed. Through the loss model of LIM, best efficiency control scheme is proposed based on the vector control, by which low efficiency of LIM under light load or low speed is improved. The control scheme is proved effective through simulation under a specified speed-location curve.At last, electromagnetism resistance and braking force of several maglev vehicles are discussed. The different action of eddy current is analyzed. The principle and several conclusions are discovered, which offer some reference for the further contrast and evaluation of these maglev vehicles in the future.