Research On Driving Characteristic Of The Linear Induction Motor

The linear inductive electric motor is a transmission apparatus which transforms electric energy into mechanic energy directly. It possesses such advantages of simple structure, low noises and long durability, and it is also easy to maintain. For these reasons, it is widely used in industrial field, especially used in the totally new transporting instrument---Magnetic Levitated Vehicles (MLVs) on railway. An MLV employs the magnetic force, enabling the vehicle to float over the rails, driven by linear electric motors. So there is no mechanical contact with the ground, no loss in friction, and it is easy to maintain and convenient to use. An MLV has no traditional wheels as the ordinary vehicle does;the condition when it is working is fully controlled by the working condition of the linear electric motors;the working vertical force of the linear electric motors will bring some effects to the whole MLV System. So the study of the drawing characteristics of the linear inductive electric motors is of great significance. The MLV technology is in rapid development in China. Medium- and low-speed MLVs are people's first choices in city rail transportation for their various advantages. Utilizing the linear inductive electric motors to drive MLVs is one of the crucial technologies in low-speed MLV. The study of the drawing characteristics of the linear inductive electric motors is of practical significance to the development and actual utilization of MLV technology in China.In this dissertation, firstly, the drawing linear inductive electric motors are analyzed and the equivalent electric circuit model of the motors employing the end effects is established. Secondly, the 3-dimentional mathematical model of the air gap magnetic field of the one-sided linear inductive electric motors driven by constant current is analyzed, and the expressing formulae of the pulling force, the vertical force and the power of the motors are established according to the theory of the field of electrornagnetism. Thirdly, an emulation calculation of drawing characteristics of the linear inductive electric motors is conducted by using the soft wares of Matlab and Maple, and the emulation curve is obtained. Fourthly, the experimental results are utilized to verify the influences of air gap length and slip frequency on the drawing characteristics of the linear inductive electric motors. Lastly, the experimental data in the reference literatures are analyzed to testify the influence of air gap length and slip ratio to the drawing characteristics of the linear inductive electric motors.