4.36 SOURC36 Current Source

4.36 SOURC36 Current Source (UP19980821 ) SOURC36 is a primitive (consisting of predefined geometries) used to supply current source data to magnetic field problems. The element represents a distribution of current in a model employing a scalar potential formulation (degree of freedom MAG). The currents are used to calculate a source magnetic field intensity (Hs) using a numerical integration technique involving the Biot-Savart law. The Hs term is used in the formulation as a magnetic load on the model. See Section 14.36 of the ANSYS Theory Reference for more details about this element.

Figure 4.36-1 SOURC36 Current Source Element



4.36.1 Input Data

The geometry, node locations, and the coordinate system for this element are shown in Figure 4.36-1. The element input data includes three nodes and the following real constants (see Table 4.36-1):

TYPE

Source type - use 1 for Coil, 2 for Bar, 3 for Arc.

CUR

Total current flowing through source (i.e., number of turns times current per turn).

DY

Characteristic y dimension for source type.

DZ

Characteristic z dimension for source type.

EPS

Convergence criterion for source field (Hs) calculations for arc and coils. Defaults to 0.001. EPS represents the relative maximum difference in the field Hs calculated at any node during the iterative calculation of the source field. EPS does not apply for bar sources.

Characteristic dimensions described above are in the element coordinate system. In the case of circular sources (coils, arcs) the radius is determined from the first and third nodes (I,K). For bar sources, the length is determined from the first two nodes (I,J).

A summary of the element input is given in Table 4.36-1. A general description of element input is given in Section 2.1.

Table 4.36-1 SOURC36 Input Summary

Element Name

SOURC36

Nodes

I, J, K (nodes I, J and K define the characteristic length, current flow direction, and orient the source)

Degrees of Freedom

None

Real Constants

TYPE, CUR, DY, DZ, (Blank), (Blank), (Blank), (Blank), EPS

Material Properties

None

Surface Loads

None

Body Loads

None


As a modeling aid, a magnetic command macro, RACE, is available within the ANSYS command set. This macro enables the user to build a racetrack conductor from SOURC36 primitives. The macro is discussed in further detail in the ANSYS Commands Reference and in the ANSYS Electromagnetic Field Analysis Guide.

4.36.2 Output Data

The source element has no output of its own since it is used only to supply current source data to magnetic field problems.

4.36.3 Assumptions and Restrictions

The source element must have characteristic DY or DZ values that are greater than zero. The third node must not be colinear with the first two nodes. The nodes for this element need not be attached to any other elements. For the coil and the arc (types 1 and 3), the K-I line determines the radius (and the x axis) and the J node orients the x-y plane. For the arc (type 3) the subtended angle must not exceed 90. All source element nodes should be located a least 1E-6 units apart. Source element cannot have a zero inside radius (Radius DY/2 for types 1 and 3).

The EPS convergence criterion is a measure of the relative difference in the calculated Hs field used during an iterative numerical integration procedure for coil and arc source primitives. The default value (.001) provides for good accuracy in regions outside of the source primitive location. For highly accurate calculations within the source primitive domain, the criteria may have to be tightened (i.e., a factor of 20 increase would be represented by EPS=.00005). Tightening the convergence criteria will significantly increase the solution run time. Users concerned with accurate calculations within the coil and arc source primitive domain should experiment with the criteria until satisfied with the degree of accuracy obtained.

All currents for a magnetostatic model employing the scalar potential formulation must be specified. Whereas symmetry conditions on the finite element model may be employed, no symmetry may be employed on the current source elements.

4.36.4 Product Restrictions

There are no product-specific restrictions for this element.