Variable Reluctance

R2026b

Variable reluctance in electromagnetic systems

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Variable Reluctance block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Simscape / Foundation Library / Magnetic / Magnetic Elements

Description

The Variable Reluctance block models a variable 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 defined as the reluctance, and is dependent on the value of the input physical signal.

The block uses the equations

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

$$\Re =\frac{X}{{\mu }_0\cdot {\mu }_r\cdot A}$$

where:

• MMF is the magnetomotive force (mmf) across the component.

• Φ is the flux through the component.

• $$\Re$$ is the reluctance.

• X is the value of the input physical signal.

• μ₀ is the permeability constant.

• μ_r is the relative permeability of the material.

• A is the cross-sectional area of the section being modeled.

Connections N and S are magnetic conserving ports. The mmf across the reluctance is $$MMF\left(N\right)-MMF\left(S\right)$$, and the sign of the flux is positive when it flows 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.

Ports

Input

X — Length of air gap or thickness of section, m

physical signal

Physical signal input port that provides the value for the length of air gap or the thickness of the section being modeled.

The port name is not visible in the block icon, but you can see this name in the underlying source file by clicking the Source code link in the Description tab of the block dialog box.

Conserving

N — North terminal

magnetic

Magnetic conserving port associated with the north terminal.

S — South terminal

magnetic

Magnetic conserving port associated with the south terminal.

Parameters

Minimum length or thickness X>=0 — Minimum length of air gap or thickness of section

0 m (default) | nonnegative scalar

The minimum value of length of air gap or thickness of section. If the input signal falls below this level, the block uses this minimum value instead.

Cross-sectional area — Cross-sectional area of section being modeled

0.01 m^2 (default) | positive scalar

Cross-sectional area of the section being modeled.

Relative magnetic permeability of material — Relative magnetic permeability

1 (default) | positive scalar

Relative magnetic permeability of the section material.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2010a