Analysis of noise reduction in a low speed and high torque PMSM with tooth concentrated windings

The paper deals with acoustic noise in permanent magnet synchronous motors (PMSM) with tooth concentrated armature windings. In particular, the noise emitted by this kind of motors is investigated with reference to high-torque low-speed applications. In these cases, due to the high number of poles, the stator yoke is usually thin and it is characterized by low natural frequencies that could lead to undesired amplifications of mechanical resonance phenomena. The paper analyzes the effects of variations of stator yoke thickness on vibrations and noise emitted by the machines. The aim is to investigate the relation between noise emission and stator yoke thickness without any other variation of the machine configuration. The analysis is led by the mathematical model of PMSM, used to characterize analytically the time behavior of the radial forces that excite the machine vibrations; FEM analysis and numerical extrapolation of the machine acoustic response are performed by the software “Manatee”.