Title: A design method of a mode control and an unbalance vibration control for five-axes active magnetic bearing systems

Authors: Shinya Okubo; Yukinori Nakamura; Shinji Wakui

Addresses: Department of Electrical and Electronic Engineering, Tokyo University of Agriculture and Technology, Naka-cho, 2-24-16 Koganei-shi, Tokyo, Japan ' Institute of Engineering, Tokyo University of Agriculture and Technology, Naka-cho, 2-24-16 Koganei-shi, Tokyo, Japan ' Institute of Engineering, Tokyo University of Agriculture and Technology, Naka-cho, 2-24-16 Koganei-shi, Tokyo, Japan

Abstract: Mass unbalance of magnetically levitated rotors causes deteriorations of dynamic and static characteristics. To avoid this problem, it is necessary that mode matrices (i.e., a mode selection/distribution matrices) are adjusted appropriately. This is because these matrices are set based on the rotor's centre of gravity and magnetic force coefficients of electromagnets. It takes long time to adjust the parameters of the mode matrices by trial and error. To design these parameters efficiently, we propose an adjustment method based on experimental analysis. Experimental results of step response show effectiveness of the proposed method. On the other hand, the eccentricity of the rotor causes unbalanced vibration, which is a common problem in rotating machinery. To suppress the vibration, automatic balancing system (ABS) and peak-of-gain control (PGC) are utilised. By using the ABS (the PGC), the bearing stiffness at rotational frequency is decreased (increased). In previous works, implementation methods for these have not been presented fully. Thus, in this paper, we considered the implementation of the ABS and the PGC. Moreover, practical advantages of the PGC/ABS are demonstrated by rotational tests of a turbo molecular pump.

Keywords: active magnetic bearings; AMB; vibration control; turbomachinery; automatic balancing systems; ABS; peak-of-gain control; PGC; tracking filters; mass unbalance; magnetically levitated rotors; rotating machinery; bearing stiffness; turbo molecular pumps.

DOI: 10.1504/IJAMECHS.2013.057665

International Journal of Advanced Mechatronic Systems, 2013 Vol.5 No.4, pp.257 - 269

Published online: 12 Jul 2014 *

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