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Unformatted text preview: Lecture 2. Variable Reluctance Machine Example 1 A Ccore electromagnet has a winding of Nturns. What is the force acting in the x direction on an iron armature? Assume the iron of the Ccore and the armature to have very high relative permeability so that the flux pattern is as described below: Let The mean length of the iron path be L . The airgap path is x 2 . i H is the iron magnetic field intensity. a H is the air magnetic field intensity. Ampere’s Law ∫ ∫ ⋅ = ⋅ a J l H d d yields i N x H L H a i ⋅ = + 2 (1) i x x f armature turns N − × × × × a H a H i H Gauss Law The Bfields at the airiron interface are equal normally: μ μ μ a i i H H = (2) { ty permeabili relative i i a H H μ ⋅ = (3) Substitute (3) in (1) ( ) i N x L H i i ⋅ = + μ 2 i i x L i N H μ 2 + ⋅ = Hence ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⋅ = + ⋅ = ⋅ = x L i N x L i N H B i i i i i i 2 2 μ μ μ μ μ μ μ Let the crosssectional area of the iron be A A x L i N A B i i ⎟ ⎟ ⎠...
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 Spring '09
 BonTekOoi
 Magnetic Field, Wm, Magnetic Field Intensity, variable reluctance machine

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