Research Papers

Electromagnetomechanical Coupled Vibration Analysis of a Direct-Drive Off-Shore Wind Turbine Generator

[+] Author and Article Information
Michael Kirschneck

Faculty 3mE,
Department PME,
Delft University of Technology,
Delft 2628CD, The Netherlands
e-mail: m.kirschneck@tudelft.nl

Daniel J. Rixen

Institute of Applied Mechanics,
Technische Universität München,
Boltzmannstr 15,
D-85748 Garching b. München, Germany

Henk Polinder

Associate Professor
Faculty EWI,
Department EPP,
Delft University of Technology,
Delft 2628CD, The Netherlands

Ron A. J. van Ostayen

Associate Professor
Faculty 3mE,
Department PME,
Delft University of Technology,
Delft 2628CD, The Netherlands

Contributed by the Design Engineering Division of ASME for publication in the JOURNAL OF COMPUTATIONAL AND NONLINEAR DYNAMICS. Manuscript received February 17, 2014; final manuscript received June 5, 2014; published online April 2, 2015. Assoc. Editor: Carlo L. Bottasso.

J. Comput. Nonlinear Dynam 10(4), 041011 (Jul 01, 2015) (12 pages) Paper No: CND-14-1049; doi: 10.1115/1.4027837 History: Received February 17, 2014; Revised June 05, 2014; Online April 02, 2015

In large direct-drive off-shore wind turbine generators one challenge is to engineer the system to function securely with an air gap length of about a thousandth of the outer rotor diameter. Compared to the large diameter of the generator rotor, the rolling element bearings can only be constructed with a relatively limited size. This makes it challenging to design appropriate constructions able to transmit the large applied magnetic forces encountered in the air gap of direct drive wind turbine generators. Currently, this challenge is met by designing stiff heavy rotors that are able to withstand the forces in the air gap. Incorporating flexibility into the design of the rotor structure can lead to a lighter less expensive rotor. In order to be able to do this the magnetomechanical coupling in the air gap and its effect on the structural dynamics need to be taken into account when predicting the intended flexibility. This paper introduces an approach for a multiphysical modal analysis that makes it possible to predict the dynamics of the strongly coupled magnetomechanical system. The new method is validated using measurements of a simple lab setup. It is then applied to a single-bearing design direct-drive wind turbine generator rotor to calculate the changes of the structural dynamics caused by the electromagnetomechanical coupling.

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Fig. 2

Moving mesh around structure

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Fig. 3

The test rig used for validation measurements

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Fig. 4

Model of the XD-115 generator

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Fig. 5

Change of eigenfrequency for some modes of the XD-115

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Fig. 6

Change of the magnetic flux density in the air gap for various material models for the iron

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Fig. 7

The specific magnetic energy around a permanent magnet in the air gap and the magnetic field lines plotted for various air gap lengths. Saturation is taken into account.

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Fig. 8

Specific exchange energy on the surface where the magnetic force is applied.



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