Analysis For Propulsion Motor And Power Supply Scheme In The Middle-speed Maglev Train

At present,city scale expands unceasingly,and the demand of transportation in city increases sharply.The development of rail transit in city is an effective way to solve this problem.The middle-speed maglev train with volecity of 200 km/h is a new kind of rail transportation.The key component of traction system in Middle-speed maglev train is linear synchronous traction motors with Halbach permanent magnet and air-core coil.The characteristics and power supply scheme of the traction motor with novel structure were analyzed.The main aspects.of research work is as follows.Firstly,based on analytical method,the armature magnetic field distribution of linear synchronous motor with Halbach permanent magnet and air-core coil in one period are analyzed by equivalent surface current model of permanent magnet and Maxwell’s electromagnetic equations.The influences of permanent magnet size and length of the air gap for the amplitude and harmonic distortion rate of magnetic field in the air gap are researched.The dynamic distribution of exciting magnetic field in the air gap is analyzed,and the back EMF in the three-phase AC windings generated by exciting magnetic field is calculated.Equivalent circuit of permanent magnet linear synchronous motor with long stator in the stable state is established,and the electromagnetic parameters of the equivalent circuit are calculated.Secondly,based on the finite element method,a simulation model of the motor is established by using Ansoft Maxwell 2D software.The internal electromagnetic field distribution of the traction motor is analyzed once again to verify the result of analytical method.Power-angle characteristics of propulsion and normal force are researched,and the relationships between propulsion,normal force and the stator current,the gap length are analyzed.Dq axis inductance is calculated,and the changing rule of dq axis inductance with the changing of the stator current,the gap length is researched.The influences of different pole pitch of the mover for the normal and propulsion force are researched.Finally,a 3D simulation model of the traction motor is established,and the changes of propulsion and normal force are analyzed when misalignment occurs between the primary section and secondary section of the linear motor.Thirdly,from VVVF principle of linear motor and traction substation inverter,the traction power supply scheme of linear synchronous motor with long stator is studied preliminarily.The way of power supply of linear synchronous motor with long stator in high-speed maglev train TR08 is analyzed.The traction power supply system diagram and traction substation distribution in middle-speed maglev train are designed.Finally,calculation method of the capacity of traction substation is researched,which includes the correspondence between power supply frequency and the stator terminal voltage,drive power of linear motor with long stator,feeder cable loss,and capacity of traction converter.Through the above analysis of linear synchronous motor with Halbach permanent magnet and air-core coil,the magnetic characteristics of the motor,the electromagnetic force characteristics,electromagnetic parameters and traction power supply are given a deep insight,which can make the foundation for the next step of the motor control.