Experimental Results of Unbiased Control of 9-Pole Radial Magnetic Bearing

Previously, a generalized unbiased control strategy has been proposed for unsymmetrical radial magnetic bearings, which reduces the risk of slew rate limiting. In this paper, nine-pole radial bearings are designed and applied them to an industry-scale compressor prototype. The bearing is configured so that a single inverter can drive one radial bearing. In order to implement the control laws, phase selection algorithm is examined. When the force inversion rule is included in the plant dynamics, it is found that the plant seen by the controller is linear. Lead-filter type control laws are designed and implemented. Measurements of the sensitivities confirm the appropriateness of the control.