scholarly journals H-infinity controller design for active magnetic bearings considering nonlinear vibrational rotordynamics

2017 ◽  
Vol 4 (5) ◽  
pp. 16-00716-16-00716 ◽  
Author(s):  
Matthew O. T. COLE ◽  
Chakkapong CHAMROON ◽  
Patrick S. KEOGH
Keyword(s):  
Controller Design ◽  
Magnetic Bearings ◽  
Active Magnetic Bearings ◽  
H Infinity

Vibration Control of a Turbo Molecular Pump Suspended by Active Magnetic Bearings

2011 ◽  
Author(s):  
Kai Zhang ◽  
Jinping Dong ◽  
Xingjian Dai ◽  
Xiaozhang Zhang
Keyword(s):  
Controller Design ◽  
Magnetic Bearings ◽  
Control Algorithms ◽  
Active Magnetic Bearings ◽  
Bending Mode ◽  
High Rotation Speed ◽  
Structure Vibration ◽  
The Stability ◽  
Bending Modes ◽  
Gyroscopic Effects

In a turbo molecular pump suspended by active magnetic bearings (AMBs), vibration caused by the rotor’s bending modes, gyroscopic effects and structure vibration modes influenced the pump performance and even cause instability. Different methods were used to deal with these problems. A Cross Feedback method was effective in restraining the nutation and precession of the rotor. A Phase Shaping method provided sufficient damping for the 1st bending mode of the rotor. The structure vibration instability was avoided by adjusting the joint strength between two parts of the pump housing. The gyroscopic effects also destroyed the stability of unbalance control algorithms for the AMBs at a high rotation speed. It was shown that, to ensure the stability of the controller when the unbalance control algorithms were applied, the 1st bending frequency of the rotor should be increased. Experiment results concerning the problems discussed above were provided. With a suitable controller design and an appropriate consideration of the dynamic problems, the rotor was successfully accelerated to 27 000 rpm.

scholarly journals Implementation of vibration and stability evaluation criteria for rotating machineries equipped with active magnetic bearings

2021 ◽  
Vol 13 (1) ◽  
pp. 168781402098734
Author(s):  
Kexiang Li ◽  
Cong Peng ◽  
Zhiquan Deng ◽  
Zhongming Zhang ◽  
Kaiwen Cai
Keyword(s):  
Controller Design ◽  
Evaluation Criteria ◽  
Rotor System ◽  
Magnetic Bearings ◽  
Active Magnetic Bearings ◽  
Single Input Single Output ◽  
Single Output ◽  
Vibration Model ◽  
Rotor Balance ◽  
Rotating Machineries

Imbalance vibration is the main factor affecting the stability of rotating machineries equipped with active magnetic bearings (AMB). Accordingly, for safe and reliable operation, ISO 14839 standard sets out guidelines for measuring and evaluating the vibration and stability. However, technical approaches to realize fulfillment of the evaluation criteria have never been studied in theory. This paper presents insights of these criteria and proposes effective methods to simultaneously implement these evaluation criteria. Based on imbalance vibration model of AMB-rotor system, the theoretical connections between these evaluation indices are revealed. In order to obtain accurate vibration model of single-input single-output (SISO) AMB-rotor system, modal analysis is carried out and equivalent mass of SISO system is figured out. Afterwards, with the analysis of sensitivity function in theory, new indices of the evaluation criteria are proposed, which helps establish requirements of controller design and rotor balance quality. Finally, through experimental verification on a test rig, the limitations on the evaluation criteria can be negligible, and the proposed methods to simultaneously implement the evaluation criteria are validated.

A Case Study in Control Methods for Active Magnetic Bearings

2014 ◽  
Author(s):  
Alexander H. Pesch ◽  
Stephen P. Hanawalt ◽  
Jerzy T. Sawicki
Keyword(s):  
Closed Loop ◽  
Controller Design ◽  
Experimental System ◽  
Magnetic Bearings ◽  
Control Law ◽  
Active Magnetic Bearings ◽  
Active Feedback ◽  
Active Feedback Control ◽  
Amb System

Active magnetic bearings (AMBs) provide support to rotating machinery through magnetic forces which are regulated through active feedback control. As AMBs continue to establish themselves as a proven technology, many classical and modern techniques are being employed to address the design of the control law. The current work studies three of the controller design techniques which are common in the literature for AMB applications: PID, LQG, and μ-synthesis. A controller is designed for an AMB system using each of the three techniques. Details of the design processes are given and the resulting controllers are compared. Finally, the controllers are implemented on the experimental system and the closed-loop characteristics are measured and evaluated. This work provides a common case study to demonstrate the strengths and weaknesses of PID, LQG, and μ-synthesis control methodologies as applied to a specific AMB system.

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