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Simulation of the Noise Radiated by an Automotive Electric Motor: Influence of the Motor Defects
Abstract:
The noise radiated by an electrical motor is very different from the one generated by an internal combustion engine. It is characterized by the emergence of high frequency pure tones that can be annoying and badly perceived by future drivers, even if the overall noise level is lower than that of a combustion engine.
A simulation methodology has been proposed, consisting in a multi-physical approach to simulate the dynamic forces and noise radiated by electric motors. The principle is first to calculate the excitation due to electromagnetic phenomena (Maxwell forces) using an electromagnetic finite element solver. This excitation is then projected onto the structure mesh of the stator in order to calculate the dynamic response. Finally, the radiated sound power is calculated with the aid of a standard acoustic finite element method. The calculation methodology assumes a weak coupling between the different physical levels. It has been validated by comparison with the experiment.
This simulation only considers the excitation generated by a perfect machine. This paper focuses on the possibility to include in this simulation the defects related to a real machine such as static eccentricity, dynamic eccentricity or short-circuit in order to enhance its accuracy. The excitations are analyzed in terms of excitation content (frequency content and spatial distribution) and the consequences on the sound power radiated by the machine are discussed.