During the International Conference on Electrical Machines, EOMYS held a 2-hour tutorial on 23rd August 2020 entitled Magnetic noise & vibrations in EV HEV electric motors (e-NVH).
The presentation can be downloaded here:
Magnetic noise & vibrations in EV HEV electric motors (e-NVH)
Electromagnetically-excited noise and vibrations (e-NVH) can drive the vibroacoustic signature of electric motors used in e-mobility applications. Tackling noise issues after manufacturing can be particularly expensive and may degrade e-powertrain overall performances (efficiency, cooling, weight). Electric motor designers now have take into account e-NVH phenomena at early design stage, besides usual electromagnetic and thermal aspects. This tutorial first presents noise sources in electric powertrains, including slotting and switching excitation sources. The physical process of air-borne and structure-borne magnetic noise generation is detailed, from current to sound pressure level, including resonance phenomena. It is shown that it is particularly important to identify main magnetic force wavenumbers and frequencies during early electromagnetic design stage of electrical machines. Therefore, the analytic characterization of magnetic forces in two key EV HEV topologies is carried, namely Interior Permanent Magnet Synchronous Machines (Tesla model 3) and Squirrel Cage Induction Machines (Audi e-Tron). Differences in electromagnetic excitations is discussed and illustrated with spectrograms obtained using MANATEE® software multiphysic simulation tool.