Winding configurations and performance of heteropolar electrodynamic magnetic bearings

The requirement for high speed reliable and efficient bearing operation drove the research into magnetic bearings. In the past decades, active magnetic bearings (AMBs), which are known for their operational cost and complexity, have received significant attention, and have been utilised in high-speed industrial applications. On the other hand, electrodynamic magnetic bearings (EDBs) are a different type of magnetic bearing that offers passive, efficient and more importantly stable operation. Nevertheless, despite these advantages, EDBs have received relatively little attention. This paper focuses on the heteropolar variant of EDB, with particular emphasis on winding configurations and the effects of design parameters. A comparison between winding configurations recommended in the literature and a simpler winding configuration proposed by the authors is undertaken. It is shown that both winding configurations exhibit similar performance, in terms of restoring force production and stability. Furthermore, the effects of the leading design parameters of EDB employing the proposed windings are investigated. Moreover, to validate some of the findings a test rig is developed, and good agreement between measured and predicted forces is shown for different eccentricities.