Measurement and simulation of the vibroacoustic performance of an electric motor

Abstract

Noise and vibration of electrical machines is a major concern. Changes in the machine design to improve its efficiency can lead to unacceptable vibrations. Tools to predict its vibratory and acoustic performance at the design stage need to be developed. An improved finite element model has been developed to analyse the vibration behaviour of a permanent magnet synchronous motor (PMSM) using the finite element software ABAQUS. All components and subsets of the machine have been modelled and validated by experimental modal analysis (EMA) performed on them. Some modelling issues have been overcome so that an accurate enough model has been reached. The laminated stator, as it is formed by a pack of several steel sheets, has been treated as an orthotropic material and windings have been considered a solid orthotropic part as well. The rotor-shaft assembly has also been verified by EMA. The bearings that join the rotor to the assembly of the stator have been represented by radial springs. The electromagnetic forces are applied to the whole machine model in order to obtain the vibration response. These forces are obtained from the magnetic air-gap flux density which has been obtained with a 2D finite element model developed by FLUX. Finally, the vibration response has been used to calculate the radiated noise with an acoustic model developed in LMS