[ICEMS] Effect of lamination asymmetries on magnetic vibrations and acoustic noise in synchronous machines

AuthorsJean Le Besnerais, M. Farzam
StatusPublished in: Electrical Machines and Systems (ICEMS), 2015 18th International Conference
Date25-28 Oct. 2015
KeywordsElectrical Machines, Tolerances, Magnetic Noise, Vibration, Uneven Airgap


This paper analyses the effect of stator or rotor lamination asymmetries (non-circularities) on magnetic vibrations and acoustic noise radiated by electrical machines, and more especially by permanent magnet synchronous machines. A theoretical analysis is first carried based on permeance / magnetomotive force model. Then, some full electromagnetic and vibroacoustic simulations are run at variable speed using analytical models to validate analytical understandings. It is shown that lamination asymmetries, and in particular the number of periodic non-circularities, can significantly increase noise and vibrations levels due to Maxwell forces. The number of segments, weldings or stiffeners should be multiple of the number of pole pairs to minimize the appearance of additional resonances due to new force wavenumbers. Some conclusions can apply to other magnetic asymmetries involved in modular stators and uneven magnetization PM rotor.

Preprint and full paper

The full paper can be found on IEEE.


Airgap uneveness has a strong impact on noise and vibrations of electrical machines. The electromagnetic and vibroacoustic effect of lamination asymmetries, including parallel static, parallel dynamic and conical eccentricities can be studied in MANATEE simulation software.