Analysis Of Electromagnetic Noise And Suppression Measures Of Permanent Magnet Synchronous Motor

With the development and application of permanent magnet synchronous motor technology,vibration,and noise performance have received increasing attention.Among the many noise sources in permanent magnet motors,electromagnetic noise is the most significant and complex.Therefore,studying the mechanism of electromagnetic noise generation in permanent magnet motors and reducing and suppressing electromagnetic noise based on the characteristics of the motor itself is of tremendous research significance and value.In this thesis,a 10-pole,12-slot fractional-slot concentrated winding interior permanent magnet synchronous motor is taken as the research object for the subsequent primary studies:First of all,starting from the air-gap magnetic field of the motor,the components of air-gap magnetic density were qualitatively analyzed,and the Maxwell tensor method was used to derive the frequency and spatial order of the electromagnetic wave.The results show that the radial component of the electromagnetic wave is much larger than the tangential component.The accuracy of the electromagnetic wave theory analysis is verified by finite element simulation and the electromagnetic wave spatiotemporal distribution results obtained by two-dimensional FFT decomposition.Secondly,the source of electromagnetic noise in the motor,that is,electromagnetic vibration,was studied.The motor electromagnetic vibration generation conditions were obtained through motor modal simulation calculations and force-type analysis of spatial electromagnetic waves.The study also found a tooth modulation process in the 10-pole,12-slot motor described in this thesis,where high-order spatial electromagnetic waves are modulated into low-order electromagnetic waves with relatively high amplitudes,leading to low-order vibrations with different amplitudes.These high-order electromagnetic waves have been overlooked in previous motor vibration analyses and are the leading cause of electromagnetic vibration.Using the example of a 10 th order spatial electromagnetic wave,combined with harmonic response vibration simulation,it was found that the 10 th order electromagnetic wave is modulated to the 2nd order and causes 2nd order vibration,demonstrating the effect of tooth modulation on the electromagnetic vibration of the motor.A finite element model of the motor stator assembly was established for vibration noise simulation and prototype experimental testing,and the collected vibration noise signals were processed.The motor vibration deformation state and regularity are consistent with the theoretical analysis,and the simulation and experimental results have a high degree of coincidence.The prominent source of motor noise in the results is consistent and related to tooth modulation.Finally,further research was conducted on the theory of tooth modulation,and a design scheme for suppressing electromagnetic noise in the motor was proposed by weakening the harmonics component of the air gap magnetic density that causes tooth modulation and by introducing slots on the surface of the rotor.The proposed design scheme was evaluated from multiple aspects,including electromagnetic performance,vibration and noise,and structural strength,and the simulation results showed a significant reduction in electromagnetic noise compared to the original design without affecting the motor’s operational performance.The electromagnetic noise theoretical analysis and suppression measures presented in the article apply to other internal embedded fractional-slot concentrated winding permanent magnet synchronous motors.These can provide references in the motor design stage and have specific engineering practical significance and reference value.