Research On Magnetic Flux Switching Linear Magnetic Levitation Motor For Rail Transit

Aiming at the magnetic levitation train drive system,a six-phase hybrid excitation magnetic flux switching linear magnetic levitation motor（SHFSMLM）is proposed.Armature windings,permanent magnets and DC excitation windings are installed on the short mover of the motor,while the long stator does not contain windings and only consists of the iron core structure avoids laying windings or permanent magnets along the entire track,reducing the construction cost,the six-phase structure endows the motor with fault tolerance in the event of an open-circuit fault,reducing the risk of accidents caused by motor failure,and through the six-phase positioning force superposition reduces the total positioning force of the motor,and greatly reduces the vibration and noise when the motor is running.The main contents of the paper are as follows:（1）A six-phase hybrid excitation magnetic flux switching linear magnetic levitation motor is proposed.Firstly,the fundamental structure of the SHFSMLM is studied.Scendly,its operation mechanism is analyzed in step by the magnetic flux switching mechanism,and its electromagnetic thrust generation mechanism is analyzed by the magnetic field modulation theory.Finally,the mathematical model of the SHFSMLM is calculated,including flux linkage,voltage,and magnetic force thrust equations.（2）A six-phase hybrid excitation magnetic flux switching linear magnetic levitation motor is designed.The design process of such motors is summarized by referring to the general design method of the motors,and therefore the output power equation is deduced.The quantity of turns of the armature winding and the excitation winding is preliminarily determined,the size of the magnet,the polardistance ratio between the mover and the stator,and change them in keeping with the motor design process to get the elaborate parameters of the SHFSMLM.（3）Finite element simulation analysis of the six-phase hybrid excitation magnetic flux switching linear magnetic levitation motor is carried out.The ANSYS software is used to build the two-dimensional finite element model of the SHFSMLM for simulation analysis,obtain the no-load magnetic field distribution diagram and analysis the harmonic content of the back voltage and flux linkage waveforms by Fourier decomposition.Analysis of the magnetic field-adjusting characteristics of the SHFSMLM motor,and verification of its controllability and the practicableness of its application within the field of railroading trains.（4）The fault tolerance of the six-phase hybrid excitation magnetic flux switching linear magnetic levitation motor is analyzed.To ensure that the average electromagnetic thrust is equal before and after faults occur,the compensation current in the case of one-phase and two-phase disconnection faults is calculated respectively,and the average electromagnetic thrust and its fluctuation are compared between the compensation control and the normal state to verify the fault tolerance characteristics of the six-phase redundancy structure.