The automotive industry has entered a phase of change due to environmental considerations. Hybrid and electric vehicles are emerging and with them the need to include these new technologies in the design process, especially in numerical simulation methods.
Different types of electromagnetic excitation may occur in electric machines. In particular, Maxwell pressure is responsible for radial forces applied to electric motor stators, which can cause a deflection and possible acoustic radiation.
This paper describes a complete approach to simulate the noise radiated by electric motor stators. The principle of this multiphysics method is first to calculate the excitation due to electromagnetic phenomena 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, radiated sound power is calculated with the aid of a finite element method. The calculation methodology assumes a weak coupling between the different physical levels.
This 3-step procedure is applied to an automotive electric motor and the calculation is performed for a run-up, resulting in deflection shapes and in a radiated power spectrogram. The spectrogram locally has hot spots that depend on both the topological characteristics of the motor (number of poles and slots…) and the modal properties of the stator. The key to understanding the motor response is the analysis of the excitation in terms of frequency and spatial order and the comparison to the stator modes.