HIGH-SPEED ROTOR LOSSES IN A RADIAL 8-POLE MAGNETIC BEARING - PART 2 - ANALYTICAL EMPIRICAL MODELS AND CALCULATIONS/

The continual increase in the use of magnetic bearings in various capa cities, including high-speed aerospace applications such as jet engine prototypes, dictates the need to quantity power lasses in this type o f bearing. The goal of the present study is to develop and experimenta lly verify, general power loss equations for the high-speed operation of magnetic bearings. Experimental data from a large-scale test rotor have been presented in Part I of this study. Analytical/empirical pred ictions are presented here for the test bearings, a pair of eight-pole planar radial bearings, for comparison to the experimental results fr om Part 1. Expressions for the four loss components, eddy current, alt ernating hysteresis, rotating hysteresis, and windage, are also presen ted. Analytical/empirical predictions for the rest bearings at three d ifferent bias flux levels demonstrate good correlation with correspond ing experimental data. Throughout most of the speed range the dominant loss mechanism appears to be eddy currents.