Permanent Magnet
A permanent magnet that passively generates a magnetic field.
Description
The Permanent Magnet block models a magnet that passively generates a magnetic field. Use this block to model a magnet that neither magnetises nor demagnetises. The magnetic field of a permanent magnet has a magnetic induction that increases linearly with increasing external magnetic field strength.
The Permanent Magnet block is equivalent to the Magnetic Flux Sensor and Reluctance blocks connected in parallel or in series with the MMF source and reducer blocks.
Use the Permanent Magnet unit to parameterise the magnet based on the manufacturer’s specifications for residual magnetic induction, magnetic permeability or coercivity.
Equations
If you expose the Permanent Magnet block to an external magnetic field, the block will approximate the magnetic induction of the resulting magnetic field using one of these linear relationships:
,
,
,
where
-
- is the flux density of magnet after removal of external magnetic field, corresponds to the parameter Remanent flux density of magnet;
-
- is the relative magnetic permeability of material, corresponds to the parameter Relative magnetic permeability of material;
-
- is the magnetic permeability in vacuum;
-
- is the strength of the external magnetic field;
-
- is the coercivity of magnet, corresponds to the parameter Coercivity of magnet.
Specify which parameters the block uses to define the linear equation using the Remanent field parametrization parameter.
The linear relationship is valid only when the magnet is neither magnetised nor demagnetised. The block operates in the second quadrant of the magnetisation curve :
The magnetic flux , passing through the magnet, is defined as:
,
where
-
- parameter Cross-sectional area.
The magnetomotive force (MMF) in a block is defined as:
,
where
-
- is the Length of magnet parameter.
The MMF value in the block is defined as:
,
where
-
and are the north and south terminals of the permanent magnet, respectively. The flux is positive when it passes through the device from the north terminal to the south terminal.
Parameters
Main
Cross-sectional area - cross-sectional area of the magnet
25 mm^2 (by default) | positive scalar
Magnet cross-sectional area.
Cross-sectional area unit - unit of measurement of the magnet cross-sectional area
mm^2 (By default) | m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | um^2 | yd^2
The unit of measurement of the cross-sectional area of a magnet.
Length of magnet - length of magnet
0.02 m (by default) | positive scalar
Length of magnet.
Length of magnet unit - magnet length unit
m (By default) | cm | ft | in | km | mi | mm | um |yd
The unit of measurement for the length of a magnet.
Remanent field parameterization - Residual field parameterization method
Remanent flux density and relative permeability (by default) | Remanent flux density and coercivity | Relative permeability and coercivity
Linear coupling parameterization method .
Relative magnetic permeability of material - relative magnetic permeability
1.05 (by default) | positive scalar
Relative magnetic permeability of material.
Dependencies
To enable this parameter, set the Remanent field parameterization parameter to `Remanent flux density and relative permeability' or `Relative permeability and coercivity'.
Remanent flux density of magnet - residual flux density
1.2 T (by default) | positive scalar
Flux density of magnet after removal of external magnetic field.
Dependencies
To enable this parameter, set the Remanent field parameterization parameter to `Remanent flux density and relative permeability' or `Remanent flux density and coercivity'.
Remanent flux density of magnet unit - unit of measurement of residual flux density
T (by default) | G
Residual flux density unit.
Coercivity of magnet - coercivity of magnet
1.2 / 1.05 / (4*pi*1e-7) A/m (by default) | positive scalar
Coercivity of magnet.
Dependencies
To enable this parameter, set Remanent field parameterization to `Remanent flux density and coercivity' or `Relative permeability and coercivity'.
Coercivity of magnet unit - the unit of measurement of coercivity of magnet force
A/m (By default).
The unit of measurement of the coercivity of magnet.
Flux - magnetic flux
O Wb (by default) | positive scalar
Magnetic flux.
Flux unit - unit of magnetic flux measurement
Wb (by default) | N*m/A | mN*m/A
Magnetic flux unit.
MMF - Magnetomotive force (MMF) at the magnetic poles
O Wb (by default) | positive scalar
Magnetomotive force at the poles of the magnet.
MMF unit - unit of measurement of magnetomotive force (MMF)
A (by default) | MA | kA | mA | nA | pA | uA
The unit of measurement of MMF at the poles of a magnet.