Efficient simulation of sound propagation from electric motors – frequency-dependent modeling for development of „mid-frequency gap“
* Presenting author
Electric drives have become indispensable in many areas of our everyday lives. Electric cars and e-bikes are just some of the many products which come to mind. Increased torsional loads and mechanical performance also bring rising dynamic excitation forces which add to noise emission. Many companies today focus their strategy also on developing quieter products. From a numerical aspect, acoustic simulations become more complex at increasing frequencies. For this reason, we focus this article on suitable analysis techniques which allow us to simulate the relevant acoustic frequency range of sound propagation in an efficient and practical manner. Based on the example of an electromagnetic simulation of an electric motor, dynamic forces in the air-gap are calculated and transmitted on to the stator in line with mechanical oscillation simulation. Sophisticated mechanical frequency analysis not only allows an efficient simulation of many rotation speed points. By analysing structure-borne noise spectrums over a complete rotational speed range we finally create the well-known waterfall diagram for the machine. With the above approach, it is possible to analyse correlations between excitation forces, rotational speed, structural resonances and airborne noise already during the development phase of a motor. Thus different design variants can be assessed acoustically.