Analysis Of Vibration Characteristics Of Permanent Magnet Assisted Synchronous Reluctance Motor

Permanent magnet assisted synchronous reluctance motors have the advantages of low cost,wide field weakening range,and large salient pole ratio,and are widely used in electric vehicles,air conditioners,vacuum pumps and other fields.However,due to its complex rotor structure,strong armature response,and wide rotational speed range,the vibration is more serious than other types of permanent magnet synchronous motors.This thesis studies the root cause of the vibration problem of the permanent magnet assisted synchronous reluctance motor,and proposes measures to reduce the vibration noise of the motor.The main research contents include the following aspects:Firstly,this thesis studies the generation mechanism of electromagnetic vibration of permanent magnet assisted synchronous reluctance motor.The air-gap magnetic field of PMassisted synchronous reluctance motor under different operating conditions is studied,and the expressions of radial air-gap magnetic density and radial electromagnetic force density of PMassisted synchronous reluctance motor are deduced by analytical method,and obtained The amplitude,spatial order and time frequency of the radial component of electromagnetic force causing motor vibration under different working conditions are obtained.Secondly,the electromagnetic field model of the 6-pole 36-slot three-layer U-shaped rotor permanent magnet assisted synchronous reluctance motor is established,and Maxwell simulation is used to analyze the spatial distribution waveforms of the radial air gap flux density and radial electromagnetic force density of the motor under different working conditions.The time distribution waveform was calculated by 2DFFT transform to calculate the spatial harmonic order and frequency characteristics of radial electromagnetic force density,and the changes of radial electromagnetic force density waveform and spatial harmonic and frequency characteristics under no-load and load conditions were compared.And the spatial order and frequency order of the main radial electromagnetic force waves that cause electromagnetic vibration are analyzed.Then,the optimization design analysis is carried out on the structural parameters of the motor to reduce the electromagnetic vibration of the motor.Select a reasonable optimization range for the motor stator slot parameters and rotor auxiliary slots,conduct sensitivity analysis on the optimization variables,determine the main parameters that affect the vibration characteristics and average torque of the motor,and obtain the effects of different optimization parameters on the radial electromagnetic force,average torque,etc.Response surface for torque effects.The Pareto analysis results of the maximum radial electromagnetic force density,the maximum radiated sound power level and the minimum average torque were obtained through the multi-objective optimization algorithm,and the optimal structural design was obtained by comparing the electromagnetic characteristics before and after optimization.Finally,the electromechanical analogy method is used to calculate and analyze the free mode of the stator,and the mode shapes and natural frequencies of each order of the stator core are analytically calculated.The modal superposition method is used to simulate and calculate the modal mode shapes and natural modal frequencies of the stator core of the permanent magnet assisted synchronous reluctance motor in the free mode,and compare and analyze it with the analytical method.The influence of winding,casing,end cover and other structures on the natural modal frequency of the motor is simulated and analyzed,so that the natural modal frequency of each order of the newly designed motor can avoid the main order force wave frequency of the exciting force and effectively avoid the The resonance problem arises.