Magnetic Thrust Bearing Concepts: Tests and Analyses

The rotor/stator configurations considered are washer-shaped laminate stack (WL), tape-wound laminate stack (TL), U-shaped laminate stack (UL), solid metal (S), and solid wedge pieces. Since preloading reduces rotor vibration, the effects of preloading a WL rotor and TL stator system on the flux density/input current transfer function magnitude and phase are determined from tests. Since eddy currents result in power loss and phase lag, tests are performed on four rotor/stator pairs, i.e., WL/TL, TL/TL, TL/UL, and S/S, to find the one with minimal eddy currents. For S/S, the test results are compared with those obtained from a two-dimensional finite element analysis, for Silicon-Iron and Hiperco-27. Since overhanging the rotor beyond the stator is a common practice, the effect of this on the fringing of magnetic flux is studied using finite element analysis.