Modal Analysis and Sound Field Modeling of a Permanent Magnet Axial Flux Machine with One Stator and Two Rotors

There is a potential for increasing torque density, as well as energy efficiency of modern electric vehicle systems by incorporating axial flux machines for certain applications where these characteristics are of interest. High torque density electric machines have inherently worse acoustic behavior, while axial flux machines are still not thoroughly investigated in this area, or produced for mass applications. Single stator double rotor yokeless AFM has a high potential for automotive applications, and has to be investigated in this context, while fulfilling ever-increasing acoustic requirements. The paper presents analytical and model-based considerations of acoustic behavior of an axial flux machine, completed by combining force excitation results obtained by finite element analysis and sound field output from analytical vibratory and acoustic models.