The Influence of Permeance Effect on the Magnetic Radial Forces of Permanent Magnet Synchronous Machines

An analytical model has been developed for analyzing the magnetic radial forces of permanent magnet (PM) machines. The air-gap magneto-motive force harmonics, stator slotting effect, and rotor saliency effect are considered in the model. Extensive simulations at no-load and under load conditions are performed for analyzing the radial force and vibration modes of different PM machines with different winding and rotor topologies. Concentrated winding with ${\rm q}=0.4$ , conventional concentrated winding with ${\rm q}=0.5$ , and the distributed winding with ${\rm q}=2$ are studied taking into account also two rotor types (IPM and SPM rotor). The obtained results show that for all machine types the rotor saliency has a considerable effect on the air-gap flux density and radial force characteristics. For the SPM rotor type, the radial force modes are constant with the time, however for the IPM rotor type the rotor saliency effect induce additional time harmonics in the radial force modes (including mode zero).