A Solution for the Stabilization of Electrodynamic Bearings: Modeling and Experimental Validation

Electrodynamic bearings are a kind of passive magnetic bearings based on eddy currents that develop between a rotating conductor and a static magnetic field. Relative to active magnetic bearings, their passive nature implies several advantages such as the reduced complexity, improved reliability, and smaller size and cost. Electrodynamic bearings have also drawbacks such as the difficulty in ensuring a stable levitation in a wide speed range. The most common solution to improve the stability is to add a nonrotating damping between the rotor and the stator. Although effective, this solution implies the installation of a dedicated magnet on the rotor. This increases the rotor weight and complexity and rises some concerns about the mechanical resistance. The aim of the present work is to experimentally validate the model of an electrodynamic bearing proposed by the same Authors in a previous paper and to investigate a new solution for the stabilization of electrodynamic bearings based on the introduction of compliant and dissipative elements between the statoric part of the bearing and the ground. The performances of the proposed solution are studied in the case of a simple Jeffcott rotor by means of root loci to investigate the stability of the system. The results show an improved stability relative to the test cases reported in the literature.