Research And Analysis Of The End Magnetic Field Of The Linear Induction Motor Of Middle-low Speed Maglev Train

With the development of nearly 40 years,China’s maglev technology has made great progress and achieved some proud results.At the same time,China’s low-speed maglev technology has become mature.On this basis,it has great market demand and technical feasibility to further develop medium speed maglev,tap its advantages in urban traffic,and vigorously promote the application of technology engineering.In this paper,the single-sided linear induction motor(SLIM)is taken as the research object,and the spatial distribution of the end effect of SLIM and its influence on the motor performance are analyzed by the combination of theoretical analysis and simulation verification.Combined with Changsha maglev express line,the transverse end electromagnetic radiation of linear motor is simulated and analyzed.A method to improve the traction force of motor by using the longitudinal end effect of motor is proposed.It is proved that this method can effectively reduce the eddy current resistance and improve the traction output when the motor is running at high speed,so as to improve the operation speed of medium and low speed maglev train.Firstly,the paper introduces the structure and working principle of SLIM,makes a brief analysis and equivalence of skin effect,air gap leakage flux,winding peculiarities and cogging effect of SLIM,establishes three-dimensional mathematical model of transverse end effect and one-dimensional air gap magnetic field mathematical model of two kinds of SLIM of "full-filled slots" and "half-filled slots",and their longitudinal end effects are analyzed from the perspective of "source".Secondly,the influence of the first type of lateral end effect and the second type of lateral end effect on the performance of the motor is analyzed by Maxwell simulation software.The existence of the first lateral end effect causes the air gap magnetic field of the linear induction motor to leak to both sides of the motor.The second lateral end effect will increase the eddy current loss of the motor and reduce the energy conversion efficiency of the motor.Combined with the engineering project,a simulation model of the electromagnetic field of the linear motor of the Changsha Maglev Line for low-speed maglev trains was built.The spatial distribution and change trend of the magnetic field at the transverse end of the linear motor are obtained by simulation,and the interference of electromagnetic leakage generated by the linear motor to the equipment under the vehicle is analyzed.Then,the longitudinal end effect of SLIM is analyzed by Maxwell simulation,and the correctness of one-dimensional air gap magnetic field mathematical model of single-sided linear induction motor is verified.The first type of static longitudinal end effect will lead to the decrease of motor thrust;the second type of static longitudinal end effect makes the longitudinal end of linear motor have obvious end flux distribution.The longitudinal dynamic end effect is related to the speed.When SLIM is running at low speed,the longitudinal end effect has little effect on the air gap magnetic field.When SLIM is running at high speed,the air gap magnetic field at the inlet end of the motor is obviously weakened,and there is obvious tailing effect at the outlet end.In order to reduce the eddy current resistance of SLIM,the air gap magnetic field between two adjacent linear induction motors on the same side of the vehicle bottom is continuously uninterrupted by using the tailing effect.Finally,the mathematical models of one-dimensional air gap magnetic field of MSLIM are established and verified.According to the theoretical analysis,the motor spacing and winding arrangement suitable for "half-filled slot" MSLIM are obtained,which makes SLIM1 The tailing effect of SLIM can strengthen the air gap magnetic field of SLIM2,and the theoretical analysis results are verified by simulation;the optimization effect of this method on the motor traction is analyzed,which proves that the tailing effect of SLIM can effectively reduce the eddy current resistance and improve the traction output when the motor is running at high speed,so as to improve the operation speed of the medium and low speed maglev train.This method provides a new design idea for SLIM for higher speed engineering applications.