Design of a Highly Reliable Fan with Magnetic Bearings
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ISMB14, 14th International Symposium on Magnetic Bearings, Linz, Austria
Long term analysis at ebm-papst St. Georgen GmbH & Co. KG showed that bearing failures are responsible for 90% of compact fan breakdowns. A magnetically levitated impeller has no contact with the stator and therefore the life expectancy can be essentially increased. This paper presents the design of a magnetically levitated fan. To meet the low-cost requirement, passive magnetic bearings (PMBs) are used to stabilize the radial and tilt de?ections of the rotor. By applying an optimized viscoelastic support to the stator, suf?cient damping is introduced to the passively stabilized degrees of freedom. The optimization of the stiffness and damping is discussed and the design of the key components, namely the PMB, the active magnetic bearing (AMB) and the passive damping device, is described. Finally the built prototype and measurements are presented.