Hybrid Approach for the Modeling of Magnetic Force Excitations in Multipole Wind Turbine Generators Considering Air Gap Imperfections

Alexander Kern, Christoph Mulder, Kay Hameye, Jianning Dong

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review


Magnetic force excitations in the air gap of generators can lead to tonal noise emissions of direct-drive wind turbines. Besides the magnetic circuit design, the generator air gap topology has an impact on the excited vibration modes and their frequencies, respectively. For the model-based analysis of the excited force density waves, the spatial and temporal distribution of the air gap magnetic flux density has to be modeled accurately, since it is directly linked with the interfacial forces by the Maxwell stress tensor. Electromagnetic simulations by finite elements consider nonlinear effects, as e.g. saturation, and are therefore convenient for the quantitative analysis. The processing of finite element meshes for the stated purpose is however cumbersome, since many full-models of huge structures (multipole) are necessary. Semi-analytical approaches using conformal maps are efficient for analyzing air gap deformations linearly, even though they do not consider the saturation behavior implicitly. In this work, an efficient hybrid approach for the modeling of force excitations by multipole generators considering air gap imperfection is presented. The calculation method combines electromagnetic 2D-finite-element results of symmetrical units with permeance functions of deformed air gaps obtained by conformal mapping to study the spatial and temporal shape of excited force density waves along the whole generator circumference.
Original languageEnglish
Title of host publication2021 IEEE Energy Conversion Congress and Exposition (ECCE)
Subtitle of host publicationProceedings
Place of PublicationDanvers
Number of pages8
ISBN (Electronic)978-1-7281-5135-9
ISBN (Print)978-1-7281-6128-0
Publication statusPublished - 2021
Event2021 IEEE Energy Conversion Congress and Exposition (ECCE) - Virtual at Vancouver, Canada
Duration: 10 Oct 202114 Oct 2021


Conference2021 IEEE Energy Conversion Congress and Exposition (ECCE)
Abbreviated titleECCE 2021
CityVirtual at Vancouver

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care

Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


  • Generators
  • Hybrid power systems
  • Acoustic Emission and Vibration
  • Modeling
  • Air Gap Imperfections
  • Nonuniform Air Gap


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