Minimization of Forced Vibrations of a Magnetically Levitated Shaft due to Magnetization Tolerances
Sprache des Vortragstitels:
12th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, 17. - 22.02.2008
Sprache des Tagungstitel:
This paper discusses a magnetically levitated shaft where the radial movements are passively supported by permanent magnets. The axial rotor position is stabilized by an active magnetic bearing. Because of the comparatively weak radial stiffness of the permanent magnet radial bearings, the investigation of the rotordynamic behavior is crucial for the design of the whole system. The rotor position where the shaft is free of radial magnetic forces defines the magnetic axis of the system. Due to mechanic and magnetic tolerances this axis does generally not coincide with the symmetry axis and depends on the rotor angle. Concerning forced vibrations this effect as well as unbalance are the major internal excitations. The paper describes a method to minimize the vibrations caused by magnetic tolerances. Furthermore, it shows the forces and displacements below and above the resonance frequency with and without the proposed compensation.