An option to hybrid Maxwell/Lorentz type self bearingmotors and their inherent trade-off between bearing forceand motoring torque with PM magnet thickness is onewhich utilizes Lorentz forces for bearing and motoringforce production. A slotless version of this type of selfbearing motor, and its test rig, are discussed in this paper.The test rig includes the motor, along with a conventionalmagnetic bearing, a shaft assembly, radial positionsensors and an optical encoder. Experimental results arepresented showing the force versus current relation forthe self bearing motor and indicates that several of thedestabilizing side pull forces predicted by theory may beneglected in practice. In particular, the cross coupledbearing current gain for the motor is experimentallyshown to be negligible as compared to the direct bearingcurrent gain. This result provides the basis for stabilizingcontrol of the motor. The current gain for the torqueproduction was measured as 2.5 N-m/A, and that forbearing force production was measured as 48.2 N/A.These results are shown to agree well with theory.
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