Nonlinear electromagnetic effects on magnetic bearing performance and power loss

Magnetic bearings are now being used in many applications. One of their features is their ability to apply force without contact. Thus they do not wear out from friction and are quiet. Magnetic bearings have very low levels of parasitic drag torque and force, especially at lower speeds. Active magnetic bearings can utilize microprocessors and feedback to control or excite vibrations in a manner that is unique from all other types of bearings.; This dissertation presents methods to design magnetic bearings and makes some advances to them. The circuit model equations for a homopolar bearing are presented and a solution is found including the effects of magnetic flux saturation and laminate stacking. Circuit model equations for thrust bearings are presented. Linearized frequency dependent reluctance elements are incorporated into these equations. The equations are arranged to predict the frequency dependence of thrust bearings and the predictions agree with measurements.; Finite element models are used extensively to back up the circuit model results. The drag torque caused by high rotation speed is calculated by the finite element method. The accuracy of these calculations is confirmed by comparison to measurements available in previously published experiments. Predictions of the drag torque in homopolar bearing rotor spacers are presented. The finite element method is also used to confirm the performance equations derived for a novel thrust bearing and a novel radial bearing, and it is also used to confirm the advanced circuit equations which are demonstrated on homopolar bearings.