Calculation And Analysis Of Air Gap Magnetic Density And Electromagnetic Torque Of High Speed Permanent Magnet Synchronous Motor

As an important part of the precision manufacturing industry,high-speed permanent magnet motors have become increasingly demanding due to their superior performance such as high-efficiency,energy-saving,and high power density,and their applications have become more widespread.Therefore,higher and higher requirements are imposed on the motor system.Due to the torque pulsation content of the high-speed motor,the stability,controllability of the rotational speed,electromagnetic vibration and noise,etc.are closely related to the magnetic field of the motor,Therefore,only the accurate design and calculation of the magnetic field and the electromagnetic torque of the permanent magnet motor can make a reasonable evaluation and judgment of the performance of the motor,and then estimate and optimize the performance index of the motor.In view of the above problems,this paper starts with the structural design and electromagnetic design of the motor,and conducts in-depth research on the air gap flux density and electromagnetic torque of the motor.The main contents include the following aspects:(1)Structure design of high speed permanent magnet synchronous motors.The structure,classification and principle of the motor were analyzed.The mechanical properties,structural strength and electromagnetic characteristics were considered comprehensively.Based on the requirements of the electromagnetic design for the permanent magnets,the strength design calculation and ANSYS simulation analysis of the permanent magnets were performed,Initially designed the stator and rotor structure and size parameters of the motor.a 2.2kW two-pole high-speed permanent magnet synchronous motor design for this subject was completed.(2)Calculation and analysis of air-gap magnetic flux of permanent magnet synchronous motors.For the surface-mounted permanent magnet synchronous motor,the numerical analysis of the electromagnetic field is used to theoretically analyze the air gap flux density of the motor.The air gap length,permanent magnet thickness,pole arc coefficient,eccentricity,and magnetization method for the air gap are respectively discussed.The influence of the size of the magnetic density and its distribution,and the simulation of the air-gap flux density waveform and back-EMF waveform were performed by Ansoft finite element software.The effects of magnetism on magnetic field distribution and magnetic induction strength of the motor when the permanent magnet is demagnetized,demagnetized or destroyed are studied,which provides a basis for the detection of the performance parameters of the motor during operation.(3)Analysis of electromagnetic torque and speed characteristics of high-speed permanent magnet motor.Based on the theory of electromagnetic field,combined with magnetic circuit calculation and magnetic field analysis methods,Three kinds of electromagnetic torque calculation method of power method,Maxwell method and virtual displacement method were analyzed respectively.The calculation of electromagnetic torque and rotation speed characteristics were performed using Ansoft software.The acceleration characteristics of the motor under different load torques were studied.The mechanism of the cogging torque and the influence of the cogging torque on the electromagnetic torque were analyzed and discussed.(4)Experimental testing of permanent magnet synchronous motor performance.The air gap magnetic flux density,back electromotive force,electromagnetic torque,motor speed characteristics and main electromagnetic parameters during operation were measured to verify the accuracy of theoretical research in the paper.