17.3 Surface-Defined Current Source

Defines a coil region in the finite-element mesh and assigns a uniform current density to the elements in that region. The coil region can have a rectangular cross-section.

Settings

SDEFCOIL(17.3) JSON key: surface-defined current source object

SERIES_ID(17.3) Series ID.

IN_ROTOR(17.3) Flag indicating whether the defined region is in the rotor.

MAT_ID(17.3) Material ID assigned to the region.

SMAT_IDS(17.3) Material IDs of the faces surrounding the conductor.

CURRENT(17.3) Normalized current value.

SIGMA(17.3) Element conductivity

CAL_Je(17.3) Flag indicating whether eddy currents in the defined region are considered

Input format

Text-format section

Type:

Fixed parameter set 1

Number of lines:

2

Number of parameters:

4, 7

Text format

* SDEFCOIL * SERIES_NO * NO_PARTS * OPTION *
SDEFCOIL       I          I            I
* MAT_ID * S_ID1 * S_ID2 * SID_3 * SID_4 * CURENT * SIGMA *
    I       I        I       I      I        E        E

JSON format

JSON format from 2024.11

"17_Field_Source" :
[
    {
        "SDEFCOIL" :
        {
            "SERIES_ID" : I,
            "IN_ROTOR" : I,
            "data" :
            [
                {
                    "MAT_ID" : I,
                    "SMAT_IDS" : [ I, I, I, I ],
                    "CURRENT" : E,
                    "SIGMA" : E,
                    "CAL_Je" : I
                }
            ]
        }
    }
]

Detailed description

SDEFCOIL defines the four faces of a rectangular-cross-section coil region and makes the current density uniform in the elements within that region. It can also define a trapezoidal-cross-section coil region; the current density is somewhat nonuniform, but the total current does not change.

Hint

In two-dimensional analysis, SDEFCOIL is particularly useful for axisymmetric calculations.

In three-dimensional analysis, SDEFCOIL is useful for modeling motor coils including the coil ends and for modeling transformer coils.

SDEFCOIL

SDEFCOIL(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [1, 1]

Type:

String (S)

Description:

Specifies the surface-defined current source SDEFCOIL.

SERIES_ID

SERIES_ID(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [1, 2]

Type:

Integer (I)

Description:

Source-term identifier.

IN_ROTOR

IN_ROTOR(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [1, 3]

Flag indicating whether the defined region is in the rotor

Value	Description
0	In the fixed part. Default value
1	In the moving part.

Required for steady AC analysis with slip caused by sliding motion when N_CORRECT(8) ≠ 0.

data

data(17.3)

JSON key:

Surface-defined current source data

data is an array with one entry for each SDEFCOIL element.

MAT_ID

MAT_ID(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [2, 1]

Type:

Integer (I)

Description:

Material ID of the elements to which the surface-defined current source is assigned ( MAT_ID(16.1) ).

SMAT_IDS

SMAT_IDS(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [2, 2]

Type:

Integer array (I)

Number:

4

Description:

Material IDs of the faces surrounding the conductor. Specify them in an array in the right-handed order relative to the current direction.

“SMAT_IDS” : [ 1, 2, 3, 4 ]

The direction toward the front of the page is positive

• 1: Top face

• 2: Left face

• 3: Bottom face

• 4: Right face

CURRENT

CURRENT(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [2, 3]

Type:

Real (E)

Unit:

A

Description:

Normalized current passing through the face.

For a wound coil, it may be easier to understand this value as the number of turns.

SIGMA

SIGMA(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [2, 4]

Type:

Real (E)

Unit:

\(S/m\)

Description:

Electrical conductivity of the element. The series resistance is calculated.

CAL_Je

CAL_Je(17.3)

Text-format section

Fixed parameter set 1

[row, col] = [2, 5]

Flag indicating whether eddy currents in the defined region are considered

Value	Description
0	Do not consider eddy currents in the defined region Default value
1	Considers eddy currents in the defined region. The conductivity specified by SIGMA(16.1) is used.

Caution

• Surface-defined current-source input is effective for rectangular-cross-section coils. The elements must be in the total-potential region.

• Assign a material ID to the volume elements of the coil conductor. The conductor may be divided into parts with different material IDs. Define the four surrounding faces of the coil-conductor region as surface elements and assign a different material ID to each face. Define the surface-element orientations toward the inside of the coil conductor.

• The MAT_ID(16.1) values must be defined in the input mesh data file. For these material definitions, set SIGMA(16.1) = 0 and MU(16.1) = 1.0.

• Connection to CIRCUIT(17.8) or NETWORK(17.9) is required.

Example definition of SDEFCOIL