High-speed synchronous machines: Magnetic pulling tensioning forces calculation approach

This paper presents the calculation approach acceptable for evaluation of magnetic pulling tensioning forces acting between the rotor and stator due to rotor eccentricity for choice of electromagnetic bearings for high-speed synchronous electrical machines, permanent magnet machines (PMSM). The aim of this research is to study these forces in no-load mode and in the rated mode. On the basis of the 2D electromagnetic field distribution using finite-element calculation the electromagnetic tensioning forces have been derived with accuracy sufficient for practical purposes. High spatial harmonics of resultant electromagnetic field of air gap magnetic flux density and saturation of magnetic circuit is taken into account. It has been determined that both the high spatial harmonics and saturation have an influence on the increasing of value of electromagnetic tensioning forces due to rotor eccentricity for different types of machines.