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Home / Examples / Magnetic Analysis (Gauss, Static Analysis/Harmonic analysis) / Example 11: AC Characteristics of Helical Coil
Example 11: AC Characteristics of Helical Coil
General
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AC current flows in a helical coil.
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The coil's inductance and impedance, and the vectors of the current density are also 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 [Gauss] |
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Analysis Type |
Harmonic Analysis |
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Options |
N/A |
The frequency of the current is set to 50 [kHz].
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Tab |
Setting Item |
Settings |
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Mesh tab |
Frequency-Dependent Meshing |
Reference Frequency: 50x103 [Hz] |
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Harmonic Analysis |
Sweep Type |
Single Frequency |
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Frequency |
50×103 [Hz] |
Set the Mesh Tab as follows.
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Tab |
Setting Item |
Settings |
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Mesh tab |
Meshing Setup |
Automatically set the general mesh size: Deselect General Mesh Size: 1.5[mm] |
Model
A helical solid body Coil (coil) is defined.
Its inflow/outflow faces are extended to the outside of the air domain. They contact the electric wall of outer boundary condition.
In the magnetic harmonic analysis, inflow/outflow faces must be outside of the air domain. (for the purpose of calculation with FEM)
In this example, air domain is set to be created automatically. Therefore, the inflow/outflow faces are extended to the outside of air domain.
Body Attributes and Materials
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Body Number/Type |
Body Attribute Name |
Material Name |
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0/Solid |
Coil |
008_Cu * |
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3/Solid |
Coil |
008_Cu * |
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4/Solid |
Coil |
008_Cu * |
* Available from the material DB
Body attribute is set up as follows to apply current to the coil.
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Body Attribute Name |
Tab |
Settings |
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Coil |
Current |
Waveform: AC Current: 1 [A] Turns: 1 [Turns] Direction: Specify Inflow/Outflow faces Select Inflow face and Outflow face. |
Boundary Conditions
No setting.
Results
To see the results of inductance and impedance calculation, go to the [Results] tab
and click [Show Numerical Summary Table] 
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The inductance of the coil is output as follows.
The impedance is as follows.
The vectors of the magnetic field are shown below.
The vectors of the current density are shown below.
Unlike the static analysis, the current is distributed inside the coil and highly concentrated near the surface.