Design And Performance Calculation Of Linear Induction Traction Motor For Urban Rail Traffic

Linear induction motor has very superior characteristics,such as high climbing ability,small turning radius,and no intermediate transmission.However,there are still many problems,such as low efficiency,lateral force and normal force,and the effect of transverse and longitudinal direction.So it is very important to design and analyze the linear induction motor.This paper based on the one-dimensional theory of linear induction motor establishes the equivalent circuit of linear induction motor.Based on the equivalent circuit,the thrust,efficiency and power factor of linear motor are analyzed and calculated.But the equivalent circuit obtained by one dimensional theory can not find the normal force,so the multi-layer traveling wave theory model is established,thus the normal force is obtained.In order to further analyze the linear motor,a concept of secondary impedance angle is put forward,and the influence of the angle on motor thrust,normal force and eddy current loss is analyzed.Through the equivalent circuit of the linear motor,this paper writes the Matlab program and designs a linear induction motor.Then,a three dimensional modeling software is used to build a testing platform of roller linear motor,and the location of the sensor is determined,so that thrust and normal force can be measured.The simulation calculation is carried out to verify the feasibility of the linear motor test platform by the simulation calculation of the deformation of the test platform under the condition of mechanical stress.In order to further analyze the electromagnetic characteristics of the motor by using the finite element method,the eddy current distribution of electromagnetic field in the motor and the secondary aluminum plate were calculated to obtain the magnetic field and eddy current distribution in the plate surface.This paper analyzes the relationship between magnetic field and eddy current and three-dimensional force,and gets the distribution map of the surface Lorenz aluminum force of each component.After that,the finite element method is used to analyze the special condition when the linear motor is in lateral offset.The distribution of magnetic field,eddy current and Lorenz force on the aluminum plate is obtained.The distortion rate of the longitudinal component of the current density,the distortion rate of the magnetic dense normal component and the distortion rate of the lateral force are put forward,and the calculation and analysis of each quantity are carried out.Finally,the efficiency of the linear induction motor is low,which is a major factor restricting the development of the linear induction motor.In order to improve the performance of the motor,this paper uses genetic algorithm to optimize and design linear motor of cap type secondary.In order to be able to determine the four variables of cap secondary structure parameters as optimization variables,thrust,efficiency,power factor and secondary weight is used as the optimization objective function,considering the constraint conditions,and this optimization succeed in promoting performance of linear induction motor.