Research On The High Frequency Vibration And Noise Of The Permanent Magnet Synchronous Motor

The vibration and noise of permanent magnet synchronous motor (PMSM) is animportant index to the motor performance. For diminutive PMSM, theelectromagnetic force between the stator and the rotor is the main cause of theelectromagnetic vibration of motor. The electromagnetic force between the statorand the rotor can be decomposed into the radial electromagnetic force and tangentialelectromagnetic force. The tangential electromagnetic force mainly produces torque.The radial electromagnetic force will cause the vibration of the motor. It’s the maindirection of this paper.This paper first introduces the related theory of vibration and noise. Themathematical model of the multiple-degree-of-freedom system is built. The complexmode theory of the multiple-degree-of-freedom system is educed under thecondition of nonlinear damping. The acoustic wave equation in the ideal fluidmedium is built. It lays the foundation for the study of the problems of the highfrequency electromagnetic vibration and noise of PMSM, but also provides atheoretical support for the related calculation and finite element simulation.Secondly, this paper studies the radial electromagnetic force act on the statorteeth internal surface of the PMSM. The radial electromagnetic force is theexcitation source to cause the motor vibration. According to the Maxwell stressequation, the radial electromagnetic force wave of stator tooth internal surface perunit area is obtained by air-gap field of PMSM. The main time and space harmonicscomponents of the radial electromagnetic force wave are analyzed in case of no-load,the motor driven by sinusoidal current and the motor driven by frequency converter.Finite element simulation analysis was carried out, to validate the analytical theory.Thirdly, this paper studies the influence of the permanent magnet synchronousmotor structure on the modal of the stator core. This paper presents a single ringtype electromechanical analogy method to calculate the structure modal of statorcore. The stator core and winding is treated as anisotropic composite material. TheirStructure property parameters of each direction are determined. Thethree-dimensional structural model of stator core, stator core with winding, statorwith case and end cover and the motor are established. The effects of the variousparts of the motor stator structure modal are studied by ANSYS finite elementsimulation. The mode shapes and corresponding modal frequencies provide areference and basis for the study of motor vibration.Finally, in order to study the vibration and noise of motor caused by the radialelectromagnetic force, the transient kinetic analysis model of the stator system of motor is established. The weak coupling of electromagnetic and structure is adoptedto load. The vibration of motor is calculated in both case of the motor driven bysinusoidal current and the motor driven by frequency converter. The Vibrationdisplacement and frequency of the various parts of the motor are obtained. Theeffectiveness of periodic frequency modulation control method to restrain the highfrequency electromagnetic vibration and noise of motor is proved by comparing thevibration and noise radiation of PMSM under fixed frequency modulation controlmethod with under sinusoidal periodic frequency modulation control method.