Electromagnetic vibration and noise assessment for surface mounted PM machines

Analysis of electromagnetic vibration and acoustic noise assessment and methods to minimize resultant sound power level for low noise motor design is presented in this paper. The linear model of the exciting force wave is derived to evaluate the exciting force and to optimize the design of stator winding, rotor PM shape and rotor PM skew angle for minimization of sound power level for low noise motor design. Mode number and frequency of the exciting force wave, natural vibration frequency, maximum vibration velocity and maximum vibration displacement of main vibration source are introduced to evaluate machine vibration. Resultant sound power levels for the cylindrical sound wave and the plane sound wave models are introduced to analyze the acoustic noise assessment of both axial and radial flux PM machines respectively. Finally, electromagnetic vibration and acoustic noise assessment of both radial and axial flux surface mounted motor structures are completed and illustrated in the paper.