# Fundamental Reluctance

Simplified implementation of magnetic reluctance

## Library

Magnetic Elements

## Description

The Fundamental Reluctance block provides a simplified model of a magnetic reluctance, that is, a component that resists flux flow. Unlike the Reluctance block, which computes reluctance based on the geometry of the section being modeled, the Fundamental Reluctance block lets you specify a value of reluctance directly as a block parameter.

The block is based on the following equation:

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

where

 MMF Magnetomotive force (mmf) across the component Φ Flux through the component $\Re$ Reluctance

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.

### Variables

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

Nominal values provide a way to specify the expected magnitude of a variable in a model. Using system scaling based on nominal values increases the simulation robustness. Nominal values can come from different sources, one of which is the Nominal Values section in the block dialog box or Property Inspector. For more information, see Modify Nominal Values for a Block Variable.

## Parameters

Reluctance

The ratio of the magnetomotive force (mmf) across the component to the resulting flux that flows through the component. The default value is `8e4` 1/H.

## Ports

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.

## Version History

Introduced in R2014a