Vibrations and Acoustic Noise Analyses of Modular SPM Machines

This paper investigates the vibrations and acoustic noise behavior of some equal tooth width, unequal tooth width and modular surface mounted permanent magnet machines. The investigations are based on finite element analysis (ANSYS) and the performances such as radial force (and airgap magnetic pressure), vibration modes (shapes and resonant frequencies), radial displacement and acceleration of the stator, and sound pressure level have been calculated and compared amongst different machines. It has been found that due to the existence of flux gaps in stator alternate teeth, at the same operating condition (phase current and rotor speed), the modular machines can reduce the sound pressure level by up to 15dB compared to the equal tooth width permanent magnet machines. A similar reduction in sound pressure level can be achieved by adopting the unequal tooth width permanent magnet machine.