Simulation of the Airborne and Structure-Borne Noise of Electric Powertrain: Validation of the Simulation Methodology

摘要

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. Even if the excitation due to electromagnetic phenomena of electric motors is well known, the link to the dynamic excitation generating vibrations and noise is not done. The purpose of this work is to propose 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. Other low frequency phenomena such as balancing may be added to the signal in order to enhance the simulation accuracy. This 3-step procedure is applied to an electric motor of an automotive drivetrain. The calculation is performed for a run-up, resulting in deflection shapes and in a radiated power spectrogram. The acoustic pressure due to the electrical machine is also calculated and the noise can be reviewed for different motor speeds. One typical application could be the evaluation of the structure borne and airborne noise generated in the cabin and the aural assessment of future powertrains.