Example36 Inductor with Superimposed DC (High Frequency)

General

The inductance of a high-frequency inductor with superimposed DC is analyzed.
The minor-loop permeability is used.
This is an harmonic analysis.The high-frequency characteristics such as skin effect are taken into account.
See Exercise 28 for static 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	Harmonic analysis
Options	None

The frequency of the current is set to 1[MHz].

Tabs	Setting Item	Settings
Mesh	Frequency-Dependent Meshing	Reference frequency: 1×10^6[Hz]
Harmonic Analysis	Sweep Type	Single frequency
Harmonic Analysis	Frequency	1×10^6[Hz]

Set the Mesh Tab as follows.

Tab

Setting Item

Settings

Mesh

Meshing Setup

Automatically set the general mesh size: Deselect

General mesh size: 2[mm]

Model

A helical solid body Coil (coil) is defined.

Its inflow/outflow faces are extended to the outside of the ambient air. They contact the electric wall of outer boundary condition.

In the magnetic field harmonic analysis, inflow/outflow faces must be outside of the ambient air. (for the purpose of calculation with FEM)

In this exercise, ambient air is set to be created automatically. Therefore, the inflow/outflow faces are extended to the outside of ambient air.

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
0/Solid	Coil	008_Cu *
4/Solid	Coil	008_Cu *
5/Solid	Coil	008_Cu *
6/Solid	Core	Core_Nonl_Minor

* 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. It is a static analysis.
Then, by using the minor loop and this magnetic field, the permeability for harmonic analysis is obtained, and the inductance is calculated.

Material Name

Tab

Setting

Core_Nonl_Minor

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
10	130×10^ -3
20	220×10^-3
30	300×10^-3
40	350×10^-3
50	380×10^-3
60	400×10^-3
70	410×10^-3

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
10	1.3×10^-3
20	2.2×10^-3
30	3×10^-3
40	3.5×10^-3
50	3.8×10^-3
60	4×10^-3
70	4.1×10^-3

This B-H curve is for AC operation.
It is called Minor Loop.

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

The value of current set here will be the value of the superimposed DC.

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

Body Attribute Name

Tab

Setting

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 calculation, go to the [Results] tab

click [Table] .

The vectors of the magnetic flux density are shown below.

See other Magnetic Analysis examples.