This tutorial on magnetic noise control techniques of electric machines was presented at the International Conference on Electrical Machines in Valencia, 5th September 2022 by J. Le Besnerais.
The tutorial first recalls the causal chain of magnetic noise generation, from electromagnetic field to sound pressure field, focusing on acoustic noise due to stator yoke vibrations in Permanent Magnet Synchronous Machines. The main noise control techniques focusing on magnetic circuit dimensions are then reviewed: slot/pole combination, winding design, pole shaping, skewing (V-shape, linear), slot opening and stator / rotor notching.
For each technique, the theoretical optimal design values are provided when possible, and a numerical simulation with Manatee e-NVH software is run to illustrate the effect of the design variations on magnetic noise, average electromagnetic torque and torque ripple. Open circuit and full load variable speed results are presented. Examples are applied on a 48s8p IPMSM used for automotive traction application. The different techniques are finally ranked according to their influence on magnetic noise, showing 5 to 30 dB influence on the acoustic noise level of the electrical machine depending on the technique.
The presentation is focused on e-machine noise mitigation techniques from the electromagnetic design point of view (magnetic circuit dimensions). It does not consider additional techniques that can be used at control level such as current angle, harmonic current injection, switching strategy and switching frequency. For more information check our e-NVH training webpage.
The presentation can be downloaded here: