Application of sinusoidal field pole in a permanent magnet synchronous machine to improve the acoustic behavior considering the MTPA and MTPV operation area

In this paper, various approaches to improve the acoustic behavior of a single layer interior permanent magnet synchronous machine (IPMSM) are evaluated. The studied machine is designed for the application in electric vehicles and has a maximum output power of 53.6 kW. The acoustic noise of the electrical machine is mainly generated due to vibration of the stator yoke, which is caused by the radial forces acting on the stator´s teeth. The radial force is directly correlated with the flux density in the air gap. Through modification of the outer frame of the rotor, the composition of the air gap field, which consists of the fundamental wave and its harmonics, can be modified. The distribution of the radial force density on the surface of the stator teeth will be affected and the dominant order of the radial force can be reduced selectively, which will improve its acoustic behavior.