Research On The Infuluences Of Secondary Of Linear Induction Motor For Mid-Low Speed Maglev Train To The Motor Characteristics And Control Parameters

In the urban transit, Low-speed maglev train has a better development due to its unique characteristics such as more economical, lower construction difficulty, suspended above the running track, driven by linear motors, no wheels, no transmission system, not contact with the ground so that the noise is small, no friction loss, and easy to be maintained. Linear induction motor, as the train drive system of low-speed maglev, also has some obvious disadvantages, such as the end effect does some additional losses inside the motor, which caused by the big air gap and the iron core switches, so that the motor efficiency and power factor are reduced. In order to improve the performance of LIM, the paper adopts the method of adjusting the control parameters and changing the motor secondary structure according to the impacts of motor secondary changes to the motor characteristics.Firstly, the linear induction motor’s working principle, basic concept and its unique end effect are briefly introduced, and its T-type circuit is established with considering of the end effect. The paper also analyzed the influences of the motor primary frequency, secondary aluminum thickness, secondary conductivity and the air gap size to the motor slip frequency. Then the thrust, normal force, efficiency and power factor of the LIM, with different electrical conductivity of secondary and different control parameters, are obtained after adjusting the slip frequency.Secondly, the slip frequency with different control parameters and secondary electrical conductivity is simulated in the finite element simulation software, which helps to correct the control parameters in chapter 3. Furthermore, the back-iron’s magnetic permeability and laminations are analyzed by simulation, either.Finally, by changing the secondary structure of the linear induction motor, the ladder-slit type secondary structure is selected to go on the further research. The ladder-slit secondary’s bar shape, width of slits, number of slots and the location are all optimized with the element simulation software. As conclusion, the design of motor secondary structure should consider with motor efficiency, production cost and mechanical strength, etc., and with the development of technology, the secondary structure of LIM still has spaces to be optimized.