Abstract

This paper presents the phenomenon of electromagnetic noise and vibrations in electrical machines, and focuses on the analysis of the noise reduction of skewing in surface permanent magnet synchronous machines (SPMSM). The origin of the main rotating and pulsating magnetic forces is detailed in terms of stator slotting and rotor magnet harmonics, and the optimal value of stator and rotor skew is derived. Some numerical electromagnetic and vibroacoustic simulations are then carried and confirm the analytical work. It is shown that the minimization of cogging torque does not necessarily lead to lower acoustic noise. Depending on the vibration waves responsible for noise (pulsating or rotating), the optimal rotor skew value is different. It is therefore necessary to run electromagnetic and vibroacoustic simulations to optimize the noise level of the electrical machine.

Preprint and full paper

The full paper can be found on IIAV website.

The preprint paper is available here:

Design of quiet permanent magnet synchronous electrical motors by optimum skew angle

The presentation is available here:

Presentation of “Design of quiet permanent magnet synchronous electrical motors by optimum skew angle”, ICSV23

Notes

The study has been fully carried using MANATEE simulation software. In MANATEE the 3D flux density distribution can be calculated very quickly using subdomain modeling technique and the resulting 3D magnetic forces can be projected to a 3D structural model using for instance the automated coupling of MANATEE with Optistruct. Skew or slot inclination is a widely used technique but it is particularly complex as the optimal skew depends on machine topology, load state, and skew shape. Besides, the optimal skew minimizing noise and vibrations might not be the one minmizing torque ripple.