Research Papers

Control of Magnetic Bearing With Material Saturation Nonlinearity

[+] Author and Article Information
Ali Gerami

Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22903
e-mail: ag4nt@virginia.edu

Paul Allaire

Rotor Bearing Solutions International,
Charlottesville, VA 22903
e-mail: Paul.allaire41@gmail.com

Roger Fittro

Romac Laboratory,
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22903
e-mail: rlf9w@virginia.edu

Contributed by the Dynamic Systems Division of ASME for publication in the JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL. Manuscript received February 6, 2014; final manuscript received September 30, 2014; published online January 27, 2015. Assoc. Editor: Ryozo Nagamune.

J. Dyn. Sys., Meas., Control 137(6), 061002 (Jun 01, 2015) (10 pages) Paper No: DS-14-1064; doi: 10.1115/1.4029125 History: Received February 06, 2014; Revised September 30, 2014; Online January 27, 2015

In this paper, a nonlinear modeling and control method for magnetic bearings is designed, considering the core material nonlinear high flux behavior for the first time. A combination of the generalized Lur'e method and linear matrix inequalities is used during the modeling and control design process. It is common to include a margin of safety in amplifiers and other active magnetic bearing (AMB) components. The nonlinear modeling makes it possible to operate an existing industrial AMB system with larger electric currents and thus achieve a larger maximum load capacity than existing AMB modeling and control practices allow. As a result, existing industrial AMB's can be tuned to become more resilient in dealing with external disturbances. In addition, smaller and lighter AMBs can be designed by using the proposed method, which enables achievement of the same maximum force requirement of present-day larger AMB systems.

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Fig. 1

Silicon iron magnetization curve

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Fig. 3

The balance beam (schematic view)

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Fig. 4

Each electromagnet's force

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Fig. 7

Generalized sector condition

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Fig. 8

All the models that are compared in the simulation

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Fig. 9

Simulated domain of attraction for linear and nonlinear models

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Fig. 10

Simulated transient response with nonzero initial conditions

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Fig. 11

Simulated transient response of linear and nonlinear models

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Fig. 12

Simulated time response comparison (stable linear model)

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Fig. 13

Simulated time response comparison (stable nonlinear model)



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