Homopolar 2-Pole Radial Permanent-Magnet Biased Magnetic Bearing With Low Rotating Loss

To satisfy the low loss requirement of magnetically suspended rotors, such as energy-storage flywheel, a novel radial permanent-magnet biased magnetic bearing (RPMB) with low rotating loss due to low flux fluctuation frequency in rotor core called homopolar 2-pole RPMB was proposed. A rotating loss separation method was also proposed, which was based on the Bertotti loss model, but without measurement of model´s coefficients. In virtue of the flywheel equipped with the homopolar 2-pole RPMB and the 4-pole RPMB successively, two types of bearings´ rotating loss could be separated from flywheel run-down loss. The experimental results showed that the classic loss accounts for the majority of each type bearing´s rotating loss at 30 000 rpm, and the rotating loss of the homopolar 2-pole RPMB was slightly more than half of the homopolar 4-pole RPMB. It could be inferred that the effect on the loss reduction of homopolar 2-pole RPMB would be more significant, for high speed or large power applications.