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Home / Examples / Coupled Analysis / Transient Magnetic-Thermal Analysis [Luvens/Watt] / Example 2: Heating due to the Iron Loss (AC Analysis with B-H Curve Taken into Account)
Example 2: Heating due to the Iron Loss (AC Analysis with B-H Curve Taken into Account)
General
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A coil is wound on a core. The heating due to the iron loss is analyzed.
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Permeability is set with B-H curve table.
The effect of magnetic saturation is taken into account in this example, while it cannot be taken into account in [Example 3: Heating due to the Iron Loss] of magnetic field harmonic analysis.
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The vectors of the magnetic field, the loss in the core, and the temperature distribution by the heating are solved.
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Unless specified in the list below, the default conditions will be applied.
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Obtain this session's project file. (Right-click and choose 'Save link as')
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Results will vary depending on Femtet version and the PC environment.
Analysis Space
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Item |
Settings |
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Analysis Space |
3D |
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Model Unit |
mm |
Analysis Conditions
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Item |
Settings |
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Solver |
Magnetic Analysis [Luvens] Thermal Analysis [Watt] |
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Analysis Type |
Magnetic Analysis: Transient Analysis Thermal Analysis: Steady-state Analysis |
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Options |
None |
An analysis is performed for one cycle of a 50 kHz AC input.
To reproduce its waveform well, the timestep is set by dividing the periodic time of 130 kHz by the default value of 12.
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Tab |
Setting Item |
Settings |
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Transient Analysis |
Timestep |
Automatic |
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Timestep Setting |
Number of Cycles 1 |
Graphical Objects
A coil is wound on a core.
The bodies of a core (Core) and a loop coil (Coil) are defined.
The automatically created ambient air is applicable only in the magnetic analysis, not in the thermal analysis.
Body Attributes and Materials
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Body Number/Type |
Body Attribute Name |
Material Name |
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5/Solid |
Coil2 |
008_Cu * |
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7/Solid |
Coil1 |
008_Cu * |
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6/Solid |
Core |
Core |
(*) Available from the material DB
Body attribute is set up as follows to apply current to the loop coil.
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Body Attribute Name |
Tab |
Settings |
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Coil |
Current |
Waveform: AC Current: 0.1 [A] Turns: 100 [Turns] Induced Current: Deselect Direction: Loop Coil/Magnetic Field Direction Direction Vector of Magnetic Field: X=0, Y=0, Z=1 |
The material properties of the core are set up as follows. The loss is defined in the iron loss table.
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Material Name |
Tab |
Settings |
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Core |
Permeability |
Magnetization Characteristic Type: Select B-H Curve
B-H Curve Table
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Electric Conductivity |
Conductivity Type: Conductor Conductivity: 0.1 [S/m] |
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Thermal Conductivity |
Thermal Conductivity: 10 [W/m/deg] |
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Iron Loss |
Definition Type of Iron Loss Characteristics: Iron Loss Table Frequency: 5x104 [Hz] [Magnetic Flux Density-Loss Density] Table *
* This is not the actual material's property. |
Press the Graph button. The following graph will show up.
Boundary Condition
[Natural Convection (Automatic Coefficient Calculation)] is set for the outer boundary condition (in the thermal analysis, the boundary condition surrounds the coil and core.).
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Boundary Condition Name/Topology |
Tab |
Boundary Condition Type |
Settings |
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Outer Boundary Condition * |
Thermal |
Heat Transfer/Convection |
Natural Convection (Automatic Coefficient Calculation) Ambient Temperature: 25 [deg] |
* To set the outer boundary condition, on the [Model] tab, go to
and click [Outer Boundary Condition]
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* The correction coefficient for the natural convection is calculated automatically. For the details, please refer to the Thermal tab.
To see the iron loss, go to the [Results] tab
and click [Show Numerical Summary Table] 
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The results are shown on the [Loss [W] (referring to value over 1 period from the final step)] tab as below.
The core's iron loss is approximately 0.5 [W].
The joule loss and the hysteresis loss of the core are not given because the the material property is defined on the iron loss table.
The loss characteristics are defined in the iron loss table. Only iron loss is obtained.
If it is defined by the iron loss experimental formula, the joule loss and the hysteresis loss will be output as well.
See [Loss Calculation in the Magnetic Analysis] for details of the loss.
The vectors of the magnetic field are shown below.
The vectors of the magnetic flux density are shown below.
The flux density is looping through the core.
The iron loss density is shown below.
The temperature contour as a result of Watt is shown below.
The core temperature goes up to around 66 [deg].