Analysis and optimization of rotor eddy current loss in homopolar radial magnetic bearings

For rotor of PM-biased Hybrid Radial Magnetic Bearing (HRMB), the eddy current losses will be significant when the speed is high. The large eddy current loss will cause significant heating of the rotor, so that temperature will rise and be uneven distribution in the rotor. The eddy current loss of rotor was studied with 3D time-stepping finite element analysis using Flux3D. Then the rotor eddy current loss was compared with different magnetic pole number, magnetic pole width, and airgap length, based on the invariable carrying capacity and airgap flux density. The results show that the rotor eddy current loss is found to first increase and then decrease as the magnetic pole number increases; rotor eddy current loss decreases significantly as the magnetic pole width and airgap length increases. The loss reduction techniques are advanced and the optimum HRMB is designed to reduce the eddy current loss according to the research. It is significant for the design of low-loss magnetic bearing.