Active magnetic bearing based force measurement using the multi-point technique

2007 ◽  
Vol 34 (1) ◽  
pp. 44-53 ◽  
Author(s):  
M.E. Kasarda ◽  
J. Marshall ◽  
R. Prins
Keyword(s):  
Force Measurement ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing

Development of Experimental Active Magnetic Bearing Device for Measurement of Mechanical Seal Reaction Force Acting on Rotor

2018 ◽  
Author(s):  
Hiroki Manabe ◽  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue
Keyword(s):  
Force Measurement ◽  
Reaction Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Mechanical Seal ◽  
Rotating Shaft ◽  
Fluid Force ◽  
Fluid Forces ◽  
Whirling Motion ◽  
Measurement And Evaluation

In turbomachinery, seals are used to prevent fluid leakage. At seal part, rotordynamic fluid force (RD fluid force), which causes whirling motion of rotor, is generated. Under certain conditions, the RD fluid force may contribute to instability of the machine. There are several cases that the whirling is accompanied by eccentricity due to the influence of gravity, or the whirling orbit becomes elliptical due to the influence of the bearing support anisotropy. In these cases, mathematical modeling of the RD fluid forces becomes increasingly complex. As a result, the RD fluid force measurement is more preferable. To improve the measurement and evaluation technology of the RD fluid force, a method to arbitrarily control whirling of the orbit is required. In this paper, RD fluid force measurement by controlling the shape of the orbit using an active magnetic bearing (AMB) is proposed. A contact type mechanical seal is used as a test specimen. When the rotating shaft is whirling, the RD fluid force due to hydrodynamics lubrication and the frictional force due to contact occur on the sliding surface. The resultant force of these forces is taken as the reaction force of mechanical seal and the measurement is performed. The measured reaction force of the mechanical seal is compared with simulation results and the validity of the proposed measurement method is confirmed.

Touchdown Bearing Contact Forces in Magnetic Bearing Systems

2013 ◽  
Author(s):  
Fawaz Y. Saket ◽  
M. Necip Sahinkaya ◽  
Patrick S. Keogh
Keyword(s):  
Contact Force ◽  
Force Measurement ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Contact Dynamics ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Operational Conditions ◽  
Contact Free

Under contact-free levitation, rotors supported by active magnetic bearings have many advantages such as allowing near frictionless rotation and high rotational speeds. They also provide the designer the capability to achieve increased machine power density. However, magnetic bearings possess limited load capacity and operate under active control. Under certain operational conditions, the load capacity may be exceeded or a transient fault may occur. The rotor may then make contact with touchdown bearings and the ensuing rotor dynamics may result in transient or sustained contact dynamics. The magnetic bearings may have the capability to restore contact-free levitation, though this will require appropriate control strategies to be devised. An understanding of the contact dynamics is required, together with the relationship between these and applied magnetic bearing control forces. This paper describes the use of a contact force measurement system to establish the force relationship. The contact force components measured by the system are calibrated against forces applied by an active magnetic bearing. The data generated can be used to validate non-linear dynamic system models and aid the design of control action to minimize or eliminate contact forces.

scholarly journals A System Identification Technique Using Bias Current Perturbation for the Determination of the Magnetic Axes of an Active Magnetic Bearing

2017 ◽  
Author(s):  
Dewey Spangler Jr. ◽  
Robert Prins ◽  
Mary Kasarda
Keyword(s):  
Force Measurement ◽  
Measurement Techniques ◽  
Magnetic Bearing ◽  
Bias Current ◽  
Active Magnetic Bearing ◽  
Mechanical Assembly ◽  
Identification Technique ◽  
Potential Improvement

Inherent in every Active Magnetic Bearing (AMB) are differences between the expected geometric axes and the actual magnetic axes due to a combination of discrepancies, including physical variation from manufacturing tolerances and misalignment from mechanical assembly, fringing and leakage effects, as well as variations in magnetic material properties within a single AMB. A method is presented here for locating the magnetic axes of an AMB that will facilitate the accurate characterization of the bearing air gaps for potential improvement in field tuning, performance analyses and certain shaft force measurement techniques. This paper presents an extension of the application of the bias current perturbation method for the determination of the magnetic center [4] to the determination of magnetic axes for the further development of accurate current-based force measurement techniques [1].

A System Identification Technique Using Bias Current Perturbation for Determining the Effective Rotor Origin of Active Magnetic Bearings

2006 ◽  
Vol 129 (3) ◽  
pp. 317-322 ◽  
Author(s):  
Robert J. Prins ◽  
Mary E. F. Kasarda ◽  
Samantha C. Bates Prins
Keyword(s):  
System Identification ◽  
Magnetic Circuit ◽  
Force Measurement ◽  
Measurement Techniques ◽  
Magnetic Bearing ◽  
Bias Current ◽  
Active Magnetic Bearing ◽  
Force Model ◽  
Air Gaps ◽  
Identification Technique

Locating the effective rotor origin of an active magnetic bearing (AMB) is an important step toward accurate characterization of the bearing air gaps for field tuning, performance analyses, and some shaft force measurement techniques. Specifically, application of current-based force measurement techniques to AMBs requires accurate modeling of air gaps in order to predict dynamic forces with accuracy. This paper discusses the application of a system identification technique that employs perturbation of the bias current and allows the user to establish the location of the effective rotor origin, an important step in characterizing the actual bearing gap. The technique analyzes the AMB system’s response to the perturbation of bias currents in conjunction with a magnetic circuit model to infer the center position. The effective rotor origin identification technique developed here does not require additional hardware and is suitable for use in the general class of AMBs in field applications. For our purposes, the effective rotor origin of an electro-magnet biased magnetic bearing is defined as the unique rotor location for which a magnetic circuit based force model of the bearing is satisfied for zero position offset of the rotor along each control axis. Note that the effective rotor origin referred to here is the radial origin.

scholarly journals Application of the Dynamic Iterative Learning Control to the Heteroplanar Active Magnetic Bearing

2020 ◽  
Vol 53 (2) ◽  
pp. 1511-1516
Author(s):  
Lukasz Hladowski ◽  
Arkadiusz Mystkowski ◽  
Krzysztof Galkowski ◽  
Eric Rogers ◽  
Bing Chu
Keyword(s):  
Iterative Learning Control ◽  
Learning Control ◽  
Magnetic Bearing ◽  
Iterative Learning ◽  
Active Magnetic Bearing
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