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Shock and Vibration
Volume 2015, Article ID 238629, 9 pages
Research Article

An Appraisal of Power-Minimizing Control Algorithms for Active Magnetic Bearings

1Ocean System Engineering Research Division, Korea Research Institute of Ships & Ocean Engineering, Daejeon 305-343, Republic of Korea
2Department of Mechatronics Engineering, Chungnam National University, Daejeon 305-764, Republic of Korea

Received 23 October 2014; Revised 18 January 2015; Accepted 20 January 2015

Academic Editor: Mohammad Elahinia

Copyright © 2015 Seong-yeol Yoo and Myounggyu D. Noh. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Active magnetic bearings consume much less power than conventional passive bearings, especially when power-minimizing controllers are employed. Several power-minimizing controllers have been proposed, such as variable bias controllers and switching controllers. In this paper, we present an appraisal of the power-minimizing control algorithms for active magnetic bearings in an attempt to provide an objective guideline on the merits of the control algorithms. In order for the appraisal, we develop an unified and consistent model of active magnetic bearing systems. The performances of the power-minimizing controllers are assessed through this model. The results show that the power-minimizing controllers indeed save considerable power when the machine state is relatively steady. However, a simple proportional-derivative type controller is on a par with the much more complex power-minimizing controllers in terms of power consumption when the machine is experiencing transient loads.