High Speed Rotor Losses in a Radial 8-Pole Magnetic Bearing: Part 2 — Analytical/Empirical Models and Calculations

The continual increase in the use nf magnetic bearings in varinus capacities, including high speed aerospace applications such as jet engine prototypes, dictates the need to quantify power losses in this type of bearing. The goal of the present study is to develop and experimentally verify general power loss equations for the high speed operation of magnetic bearings. Experimental data from a large scale test rotor has been presented in Part 1 of this study. Analytical/empirical predictions are presented here for the test bearings, a pair of 8-pole planar radial bearings, for comparison to the experimental results from Part 1. Expressions for the four loss components, eddy current, alternating hysteresis, rotating hysteresis, and windage, are also presented. Analytical/empirical predictions for the test bearings at three different bias flux levels demonstrate good correlation with corresponding experimental data. Throughout mnst of the speed range the dominant loss mechanism appears to be eddy currents.© 1996 ASME