Analysis Of Electromagnetic Field And Temperature Field Of Direct-Drive Permanent Magnet Synchronous Motor For Low-Floor Vehicles

With the development of economic and society,environmental pollution and traffic congestion are becoming more and more serious,and the demand of low-power,·low-emission and high-capacity transportation are growing higher and higher.Compared to the others,low-floor vehicle has a larger capacity,lower consumption,and it's more energy-saving and less environmental pollution,so it has been more widely used in the world.In order to reduce the height of the vehicle floor and the space under the vehicle,smaller volume and lighter traction motors are needed to use in the low-floor vehicles.The permanent magnet synchronous motors have no commutators and brushes and it does not require excitation,so theoretically there is no rotor loss and it has the advantages of small size,simple structure,etc.,so it is particularly suitable for the low-floor vehicles in modern urban rail transit.This paper firstly analyzes and designs the traction permanent magnet motor of modern low-floor vehicle based on the principle of motor design,selects the related parameters of the motor,selects the material type of the permanent magnet,and performs electromagnetic calculation of the solution through finite element analysis software,and compare the results with the conditions required by the program to verify the feasibility of the program.Then,the three-dimensional and two-dimensional models of the motor were established.Through the electromagnetic field calculation,the magnetic field distribution and related operating parameters of the motor were obtained.The experimental data was analyzed and compared with the given conditions to verify the feasibility of the design scheme.In view of the phenomenon of demagnetization of the motor,the cause of the loss of magnetism is discussed first,and then the loss of magnetism of the motor is analyzed and calculated using the finite element software from the aspects of the overall magnetic pole demagnetization and the partial polar body demagnetization.Comparing the operating difference between the demagnetization of the motor and that of the normal condition,summarize the effect of the loss of magnetization on the operation of the motor.In addition,the analysis method of the fluid in the motor is discussed.The finite element analysis software is used to analyze the heat transfer of the motor cooling structure,and the overall temperature field distribution of the cooling structure and the motor during operation is obtained,and various temperature indexes of the motor are obtained.Finally,the existing motor is structurally improved.Based on the principle of motor design,some structural parameters of the motor are changed to obtain a new motor scheme.The electromagnetic calculation of the new scheme was conducted,and the electromagnetic properties of the new scheme were studied and compared with the original scheme.The comparison result was obtained and the whole motor scheme was more able to meet the needs of the actual working conditions.The realization of the research will provide new design schemes and operational characteristics for the intercity rail transit and the driving motor of low-floor vehicles for rail transit in the city,providing reference for improving the operating efficiency of the drive motor,and making energy saving for the national economy.Make a contribution.