NVH of electric motors - a study on potential NVH metric

The electrification of powertrains poses different noise, vibration, and harshness (NVH) challenges. Whilst the broadband noise radiated by internal combustion engines masks some of the gearbox NVH, electric powertrains cannot count on this masking effect. Moreover, the nature of the motor's electromagnetic forces that drive the powertrain and the inverter feeding current to the system also exhibit tonal behaviour. It is known that the presence of tones in the radiated noise can increase the perceived nuisance of the user. In this work, a multi-body dynamics (MBD) model of an electric powertrain is developed to calculate the forces transmitted from the bearings to the housing, which then radiates noise. Sound pressure is also calculated in the vicinity of the powertrain. The Prominence Ratio is used to identify tonal bands in the spectrum and a neural network detects these prominent bands by analysing the transmitted forces.