Reluctance

R2026b

Magnetic reluctance

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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 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 uses the equations

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

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

where:

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

• Φ is the flux through the component.

• $$\Re$$ is the reluctance.

• g is the thickness of the section being modeled, or the length of air gap.

• 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.

Examples

Solenoid with Magnetic Blocks

Model a solenoid with spring return. When unpowered, the spring pulls the plunger +5mm away from the center of the coil. Turning on the power supply at t=0.1 seconds pulls the plunger into the center of the coil. At t=0.3s, a 10N external load is added to the plunger.

• Open Model

Electrical Transformer

Model a transformer using fundamental magnetic library blocks. The transformer is rated 50W, 60 Hz, 120V/12V and assumed to have an efficiency of 94%, no-load magnetizing current of 1% and a leakage reactance of 2.3%. Core losses are not modeled and the core material B-H characteristic is assumed to be linear.

• Open Model

Permanent Magnet Attached to Iron Wall

Model the forces acting on a magnet that is attached to an iron wall. You can define the interaction between the magnetic and translational motion domains using a Permanent Magnet block and a Reluctance Force Actuator block.

• Open Model

Model Oscillation Sensor Using Permanent Magnet Block

Model an oscillation sensor using the Permanent Magnet block. The sensor consists of a magnetic core with a permanent magnet that generates a magnetic field, a ferromagnetic plate attached to the core, and a conducting winding around the core.

• Open Model

Ports

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

Thickness or length of section or gap — Thickness of section or length of air gap

0.001 m (default) | positive scalar

Thickness of the section being modeled, or length of air gap.

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