Control of Unbalance Response with Magnetic Bearings

In the last decade, active magnetic bearings for rotating machinery have moved from a promising concept to industrial application. Because these bearings are active devices, they permit new methods of vibration reduction. Two methods of control have been advocated for the attenuation of transmitted unbalance response for rotors supported in magnetic bearings: feedback and adaptive open loop control. In this paper, the stability robustness of these two methods will be compared. Experimental results are presented demonstrating the efficacy of open loop control in attenuating unbalance response.