Low Loss Active Radial Magnetic Bearing

A new type of biased radial magnetic bearing is described. The main advantage of the new type of bearing is a significantly reduced, as compared with other known magnetic bearings of this class, rotor core loss. The rotor core loss reduction is achieved by replacing a typical, salient pole stator, with the control winding concentrated on the stator poles, by a much more magnetically symmetrical structure, with the control winding placed in slots evenly distributed along the stator circumference. This leads to a much more even magnetic field distribution in the air gap between the stator and rotor, and consequently reduced rotor core loss. In the paper a method of rotor core loss calculation, based on a finite element magnetic field analysis, is described. The results of rotor core loss calculations for the two types of magnetic bearings, mentioned above, are also presented.