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Magnetic reluctance


Magnetic Elements


The Reluctance block models a magnetic reluctance, that is, a component that resists flux flow. The ratio of the magnetomotive force (mmf) across the component to the resulting flux that flows through the component is constant, and the ratio value is defined as the reluctance. Reluctance depends on the geometry of the section being modeled.

The block is based on the following equations:




MMFMagnetomotive force (mmf) across the component
ΦFlux through the component
gThickness of the section being modeled, or length of air gap
μ0Permeability constant
μrRelative permeability of the material
ACross-sectional area of the section being modeled

Connections N and S are magnetic conserving ports. The mmf across the reluctance is given by MMF(N)MMF(S), and the sign of the flux is positive when flowing through the device from N to S.


To set the priority and initial target values for the block variables prior to simulation, use the Variables tab in the block dialog box (or the Variables section in the block Property Inspector). For more information, see Set Priority and Initial Target for Block Variables.


Thickness or length of section or gap

Thickness of the section being modeled, or length of air gap. The default value is 0.001 m.

Cross-sectional area

Area of the section being modeled. The default value is 0.01 m^2.

Relative permeability of material

Relative permeability of the section material. The default value is 1.


The block has the following ports:


Magnetic conserving port associated with the block North terminal.


Magnetic conserving port associated with the block South terminal.

Introduced in R2010a

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