Research On Normal Force Control Strategy Of Medium-low Speed Maglev Linear Induction Traction Motor

Compared with the subway train based on rotary induction motor widely used,the medium-low speed maglev train has the advantages of fast running speed,small turning radius,large running slope and so on,and has a broad development prospect.Linear induction motor is the key equipment of the traction drive system of medium-low speed maglev train.It needs to operate safely and stably under complicated working conditions and external conditions,and has high energy efficiency to meet the requirements of energy saving and emission reduction.In this paper,an optimal control strategy of normal force is proposed to ensure the stability of normal force of linear induction motor during train operation,so as to reduce the interference of normal force on suspension system and ensure the safe operation of train.At the same time,the loss of linear induction motor and the smooth control of train under special operating conditions are taken into account.Firstly,in this paper,the linear induction motor in medium-low maglev operation principle and the commonly used control strategy is analyzed,including normal force and levitation system,the system model,the analytical method to force as the disturbance of the suspension system,for linear induction motor in the operation of the normal force on the necessity of the targeted control.Then,this paper introduces the normal force characteristic curve and applies it to the control of medium-low speed maglev traction control system.Compared with the traditional constant slip frequency control,the normal force can be controlled smoothly and the loss of linear induction motor can be reduced at the same time.Secondly,this paper analyzes the influence of discontinuous secondary induction plate on motor parameters,normal force output and overall control,and realizes the stable control of normal force under this working condition.In order to realize the stable control of normal force under this working condition,it is necessary to accurately identify this working condition.This paper proposes a secondary discontinuous condition identification strategy based on dual-parameter identification,which can improve the reliability of the system without installing external mechanical positioning sensors.On the basis of identifying the train running to the secondary discontinuous condition,a normal force stability control strategy is proposed in this paper.Combining with the layout of the number of linear induction motors,the slip frequency in the traction control system is optimized and adjusted according to the initial stage coupling length obtained by online parameter identification,and the normal force stability control is realized.Finally,this paper compares and analyzes different control strategies through the MATLAB/Simulink simulation platform and the linear induction motor experiment platform,in order to verify the feasibility and effectiveness of the normal force optimization control strategy proposed in this paper.