Home / Examples / Coupled Analysis / Magnetic-Thermal Analysis [Gauss/Watt] / Example 4: Heating due to the Iron Loss (Temperature-Dependent Materials)

Example 4: Heating due to the Iron Loss (Temperature-Dependent Materials)

General

• A coil is wound on a core. The heating due to the iron loss is analyzed.
   

• The temperature dependencies of the core's permeability and conductivity are taken into account.
  This is bi-directional between magnetic and thermal analyses and will go back and forth until the calculation reaches the convergence.
  The calculation time is much longer than that of the model without temperature dependency.
  

• The vectors of the magnetic field, the loss in the core, and the temperature distribution after the heating are solved.
   

• Unless specified in the list below, the default conditions will be applied.
   

• Obtain this session's project file. (Right-click and choose 'Save link as')




• Results will vary depending on Femtet version and the PC environment.

 

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	mm

 

Analysis Conditions

Item	Settings
Solver	Magnetic Analysis [Gauss] Thermal Analysis [Watt]
Analysis Type	Magnetic Analysis: Harmonic Analysis Thermal Analysis: Steady-state Analysis
Options	N/A

 

The frequency of the current is set to 50[kHz].

Tab	Setting Item	Settings
Mesh Tab	Frequency-Dependent Meshing	Reference Frequency: 50x103 [Hz] Surface Treatment for Conductors: Generate skin meshes
Harmonic analysis	Frequency	Sweep Type: Single Frequency Frequency: 50x103 [Hz]

Model

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 analyzed only in the magnetic analysis, not in the thermal analysis.

 

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
5/Solid	Coil2	008_Cu *
7/Solid	Coil1	008_Cu *
6/Solid	Core	Core

* Available from the material DB

 

Body attribute is set up as follows to apply current to the loop coil.

Body Attribute Name	Tab	Settings
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.

Permeability and conductivity are temperature-dependent.

The loss is defined in the iron loss table.

Material Name	Tab	Settings
Core	Permeability	Temperature Dependency: Yes    [Temperature-Relative Permeability] Table Temperature [deg] Relative Permeability 0 3000 100 2700 500 1500 1000 30
	Electric Conductivity	Conductivity Type: Conductor Temperature Dependency: Yes    [Temperature-Conductivity] Table Temperature [deg] Electric Conductivity 0 0.1 100 0.06 500 0.02 1000 0.01
	Thermal Conductivity	Thermal Conductivity: 10 [W/m/deg]
	Iron loss	Iron Loss Calculation Type: Iron loss table    Frequency: 5x104 [Hz] [Magnetic flux density-Loss density] Table * Magnetic Flux Density [T] Joule Loss Density [W/m^3] 50x10-3 5x103 500x10-3 500x103   * This is not the actual material's property.

Press the Graph button. The following graph will show up.

Boundary Conditions

[Natural Convection (Automatic Coefficient Calculation)] is set as the outer boundary condition (in the thermal analysis, the boundary condition surrounds the coil and core.).

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Outer Boundary Condition *	Thermal	Heat Transfer/Convection	Select [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].

* The correction coefficient for the natural convection is calculated automatically. For the details, please refer to the Thermal tab.

Results

To see the iron loss, go to the [Results] tab

 

 

 and click [Show Numerical Summary Table] .

 

The joule loss is shown below.

 

 

The iron loss is shown below.

 

The core's iron loss is approximately 0.8 [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 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 87 [deg].