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:

$$MMF=\Phi \cdot \Re $$

$$\Re =\frac{g}{{\mu}_{0}\cdot {\mu}_{r}\cdot A}$$

where

MMF | Magnetomotive force (mmf) across the component |

Φ | Flux through the component |

$$\Re $$ | Reluctance |

g | Thickness of the section being modeled, or length of air gap |

μ_{0} | Permeability constant |

μ_{r} | Relative permeability of the material |

A | Cross-sectional area of the section being modeled |

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

**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`

.

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

The block has the following ports:

`N`

Magnetic conserving port associated with the block North terminal.

`S`

Magnetic conserving port associated with the block South terminal.

Was this topic helpful?