Vibration And Noise Analysis And Optimization Design Of Bearingless Permanent Magnet Motor

The permanent magnet bearingless motor has the advantages of no friction and wear,no lubrication,long service life,high efficiency,high power density,etc.However,the coupling between the torque winding and the suspension force winding embedded in the stator slot increases the difficulty of controlling the motor,which is not conducive to the application in the field of high speed and ultra-high speed.The appearance of the alternating-pole bearingless motor makes up for this shortcoming of the traditional bearingless permanent magnet motor.Its unique structural characteristics and stable suspension characteristics make it have the technical and economic advantages that the traditional permanent magnet motor cannot meet and replace in some advanced and sophisticated technical fields,and it has a good application prospect.The torque windings and suspension force windings embedded in the stator slots of the alternating-pole bearingless permanent magnet motor do not need to meet the condition of pole log difference 1 in the design,which greatly reduces the difficulty of the control system design and can have more room to improve the electromagnetic performance.The unique alternating pole rotor structure can realize the decoupling control of two stator windings.With the continuous development of new energy electric vehicle industry in recent years,the technology of permanent magnet motor has also ushered in a golden period of rapid development,and the electromagnetic vibration and noise of permanent magnet motor has become a research hotspot of the majority of engineering personnel.However,at present,there are few researches on the electromagnetic vibration noise of the stator structure of the alternating pole bearingless permanent magnet motor.Therefore,based on the analysis of the radial electromagnetic force of the motor,this paper analyzes and optimizes the electromagnetic vibration noise of an alternating pole bearingless permanent magnet synchronous motor.The main research contents are as follows: Firstly,the suspension mechanism and the basic theory of electromagnetic vibration noise of the alternating-pole bearingless permanent magnet motor are expounded.Secondly,the radial electromagnetic force harmonics of permanent magnet synchronous motor are deduced theoretically,and their characteristic frequency and spatial order are analyzed theoretically.Then,the electromagnetic field simulation model of the alternating pole bearingless permanent magnet motor is established in ANSYS Electronics Desktop to simulate and solve the radial electromagnetic force,and the amplitude,frequency and order characteristics of the harmonic electromagnetic force combined with theoretical derivation are analyzed in detail.Secondly,the multi-physical field simulation model of the motor was established based on ANSYS Workbench platform,and the modal,structural vibration and noise of the motor stator components were simulated,and the electromagnetic vibration and noise response characteristics of the motor under various current loading forms were studied respectively.Then,an analytical model of the transient magnetic field of an alternating-pole bearingless permanent magnet motor with the rotor’s eccentricity displacement was proposed.The electromagnetic force characteristics of the motor with the suspension eccentricity were studied,as well as the effects on the tooth torque and magnetic pull of the eccentricity.On this basis,the electromagnetic noise response with the suspension eccentricity was simulated and analyzed.Then the electromagnetic parameters of bearingless alternating-pole permanent magnet motor with variable structure size are studied.Finally,based on the influence of harmonic electromagnetic force on electromagnetic vibration and noise,the iterative design of the solution was completed with the help of Optis Lang optimization platform,which means changing rotor size and reducing harmonic electromagnetic force.Finally,the optimal rotor size combination is obtained,and the electromagnetic torque,harmonic electromagnetic force and electromagnetic vibration noise before and after optimization are analyzed to verify the optimization effect of the alternating-pole bearingless permanent magnet motor.The simulation results prove the effectiveness of the optimization scheme.