The effect of slot length on flux distribution and rotordynamic coefficients in magnetic actuators using a boundary perturbation method

Lyndon S. Stephens, Mark A. Casemore

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In previous work (Stephens and Casemore, 1999), the authors presented an analytical method to compute the flux distribution and negative stiffness of magnetic actuators. The method uses Fourier series expansions to model current distributions and permanent magnets as sources of magnetomotive force (MMF) on the air gap boundary and then solves the Dirichlet boundary value problem (BVP) in the eccentric annulus for the MMF within the permanent magnet and air gap regions. The method is applicable to many common magnetic actuator designs but is limited to those with MMF sources that are located opposite of a smooth (unslotted) boundary. In this paper, the method is extended to remove this limitation and include the effect of slot length on flux distribution and rotordynamic coefficients. This is accomplished by adding a boundary perturbation step to the solution that accounts for the additional reluctance of the slots. The method is applied to a sample problem and is benchmarked against a finite element model. The results show good agreement between the two models up to a certain critical slot length. This critical slot length is shown to correspond to the traditional infinite slot length (that slot length beyond which no appreciable change in flux distribution occurs). The results indicate that slots in the stator have a significant impact on the negative stiffness and that the infinite slot length assumption is valid even for shallow and wide slots.

Original languageEnglish
Title of host publicationManufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education
ISBN (Electronic)9780791878576, 9780791878576
DOIs
StatePublished - 2000
EventASME Turbo Expo 2000: Power for Land, Sea, and Air, GT 2000 - Munich, Germany
Duration: May 8 2000May 11 2000

Publication series

NameProceedings of the ASME Turbo Expo
Volume4

Conference

ConferenceASME Turbo Expo 2000: Power for Land, Sea, and Air, GT 2000
Country/TerritoryGermany
CityMunich
Period5/8/005/11/00

ASJC Scopus subject areas

  • Engineering (all)

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