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Example28 Inductor with Superimposed DC (Minor Loop Permeability)

General

  • The inductance of an inductor with superimposed DC is analyzed.
     

  • The minor-loop permeability is used.

  • This is a static analysis. The high-frequency characteristics such as skin effect are not taken into account.
    See Example 36 for high-frequency analysis.
     

  • The vectors of the magnetic field and the magnetic flux density are solved.
     

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

 

Analysis Space

Item

Settings

Analysis Space

3D

Model unit

mm

 

 

Analysis Conditions

Item

Settings

Solvers

Magnetic Field Analysis [Gauss]

Analysis Type

Static analysis

Options

N/A

Model

A loop coil (coil) and a magnetic core (core) with gap are placed.

As the magnetic field concentrates in the gap of the magnetic core, small mesh size is applied (0.2mm).

Body Attributes and Materials

Body Number/Type

Body Attribute Name

Material Name

Mesh Size

1/Solid

Coil

008_Cu *

0.5

9/Solid

NonL

NonL_mu0_2

0.5

* Available from the Material DB

 

Nonlinear material is defined on the nonlinearity table.

To solve the inductance under DC-biased condition, the magnetic field is solved first with the major loop.
Then, by using the minor loop and this magnetic field, the permeability is obtained for the inductance calculation. 

Material Name

Tab

Settings

NonL_mu0_2

Permeability

Magnetization Characteristic Type: Select B-H curve

Select “Use the minor-loop permeability”

 

B-H Curve Table

Magnetic Field [A/m]

Magnetic Flux Density [T]

0

0x10^-4

1

2×10^-4

2

5×10^-4

10

7×10^-4

This B-H curve is for DC bias.
It is called Major Loop.

 

Permeability

for Minor Loop

Magnetization Characteristic Type: Select B-H curve

 

B-H Curve Table

Magnetic Field [A/m]

Magnetic Flux Density [T]

0

0x10^-4

1

1×10^-4

2

2.5×10^-4

10

3.5×10^-4

This B-H curve is for AC operation.

 

 

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

Enter the direct current value.

AC current cannot be given. It is assumed to be significantly small compared to DC current.

Body Attribute Name

Tab

Settings

Coil

Current

Waveform: Constant

Current: 1[A]

Turns: 1[Turns]

Direction: Loop Coil/Magnetic Field Direction

Magnetic Field Vector: X=0, Y=0, Z=1

Boundary Conditions

No setting.

Results

To see the results of inductance calculation, go to the [Results] tab

 

 

 click [Table] .

 

 

The vectors of the magnetic flux density are shown below.

 

 

The figure below shows the inductance when “Use the minor-loop permeability” is deselected for NonL_mu0_2

 

 

It is greater than the value calculated with minor-loop permeability.

This indicates the tendency that the major-loop slope is greater than the minor-loop slope.

 

 



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