7.3. Reviewing the Results from a Harmonic Edge-Based Analysis

The program writes results from an edge-based harmonic magnetic analysis to the magnetics results file, Jobname.rmg (or to Jobname.rst if the electric potential (VOLT) is active). Results include the data listed below, many of which vary harmonically at the operating frequency (or frequencies) for which the measurable quantities can be computed as the real solution times cosine (Ωt) minus the imaginary solution times sine (Ωt).  Ω is the angular frequency. For more details, see the Mechanical APDL Theory Reference.

Primary data: Nodal DOFs ( AZ, VOLT, EMF)

Derived data:

  • Nodal magnetic flux density (BX, BY, BZ, BSUM)

  • Nodal magnetic field intensity (HX, HY, HZ, HSUM)

  • Nodal electric field intensity (EFX, EFY, EFZ, EFSUM)

  • Nodal electric conduction current density JC, (JCX, JCY, JCZ, JCSUM)

  • Nodal magnetic forces (FMAG; components X, Y, Z, SUM)

  • Total current density (JTX, JTY, JTZ, JTSUM)

  • Joule heat rate per unit volume (JHEAT)

  • Element magnetic energy (SENE)

Additional data are available. See the Element Reference for details.

You can review analysis results in POST1, the general postprocessor. The results are out-of-phase with the input loads (that is, they lag the input loads), and therefore are complex. They are calculated and stored in terms of real and imaginary components as detailed above.

Use POST1 to review results over the entire model at specific frequencies. For viewing results over a range of frequencies, use the time-history postprocessor, POST26.

For a harmonic magnetic analysis, the frequency range usually consists of only the AC frequency. Therefore, typically you use POST1 to review the results.

To choose a postprocessor, use one of the following:

Command(s): /POST1, /POST26
GUI: Main Menu> General Postproc
Main Menu> TimeHist Postpro

7.3.1. Commands to Help You in Postprocessing

Mechanical APDL provides a number of commands (listed below) for Postprocessing:

Table 7.1: Postprocessing Commands

TaskCommand(s)
Select the real solution SET,1,1,,0
Select the imaginary solution SET,1,1,,1
Print edge-flux degree of freedom (AZ) [5] PRNSOL,AZ
Print electric potential [6] or time integrated electric potential degree of freedom (VOLT) [5] PRNSOL,VOLT
Print magnetic flux density at corner nodes [1, 5] PRVECT,B
Print magnetic field at corner nodes [1,5] PRVECT,H
Print electric field intensity at corner nodes [1, 5] PRVECT,EF
Print conduction current density at corner nodes [1, 5] PRVECT,JC
Print total current density at element centroids [5] PRVECT,JT
Print force at element nodes [2, 6] PRVECT,FMAG
Print magnetic flux density at element nodes [5] PRESOL,B
Print electric field intensity at element nodes [5] PRESOL,EF
Print conduction current density at element nodes [5] PRESOL,JC
Print magnetic field at element nodes [5] PRESOL,H
Print total current density at element centroid [5] PRESOL,JT
Print force at element nodes [2,6] PRESOL,FMAG
Print magnetic energy [3, 5] PRESOL,SENE
Print Joule heat density [4, 6] PRESOL,JHEAT
Create element table item for centroid flux density [5], X component. (Issue similar commands for Y, Z, and SUM components.) ETABLE,Lab,B,X
Create element table item for centroid magnetic [5] field, X component. (Issue similar commands for Y, Z, and SUM components.) ETABLE,Lab,H,X
Create element table item for centroid electric field intensity [5], X component. (Issue similar commands for Y, Z, and SUM components.) ETABLE,Lab,EF,X
Create element table item for electric current density [5] field, X component. (Issue similar commands for Y, Z, and SUM components.) ETABLE,Lab,JC,,X
Create element table item for Joule heat density [4, 6] ETABLE,Lab,JHEAT
Create element table item for centroid current [5] density, X component. (Issue similar commands for Y, Z, and SUM components.) ETABLE,Lab,JT,X
Create element table item for magnetic force [2, 6] over element, X component. (Issue similar commands for Y, Z, and SUM components.) ETABLE,Lab,FMAG,X
Create element table item for element stored energy [3] ETABLE,Lab,SENE
Print the indicated element table item(s) PRETAB,Lab,1,...

  1. Average of selected elements adjacent to nodes.

  2. Force is summed over elements and distributed among nodes for coupling purposes.

  3. Magnetic energy is summed over elements.

  4. To obtain power loss, multiply by element volume.

  5. Instantaneous value (real/imaginary, at Ωt = 0 and Ωt = -90) in case of a harmonic analysis.

  6. Time-averaged value stored in both the real and imaginary data sets.

For more information about these notations, see the Mechanical APDL Theory Reference.

The ETABLE command also allows you to view less frequently-used items.

You can view most of these items graphically. To do so, substitute plotting commands for the commands whose names begin with "PL" (for example, use PLNSOL instead of PRNSOL, as illustrated below):

For this 
Command...

Substitute this
Command...

Or this GUI Path...
PRNSOL PLNSOL Utility Menu> Plot> Results> Contour Plot> Nodal Solution
PRVECT PLVECT Utility Menu> Plot> Results> Vector Plot
PRESOL PLESOL Utility Menu> Plot> Results> Contour Plot> Elem Solution
PRETAB PLETAB Utility Menu> Plot> Results> Contour Plot> Elem Table Data

You also can plot element table items. See the Basic Analysis Guide for more information.

The Ansys Parametric Design Language (APDL) also contains commands that may be useful in postprocessing, and several magnetics macros also are available for results processing purposes. For more information about the APDL, see the Ansys Parametric Design Language Guide.

The following topic, "Reading In Results Data," discusses some typical POST1 operations for a harmonic magnetic analysis. For a complete description of all postprocessing functions, see the Basic Analysis Guide.

7.3.2. Reading in Results Data

To review results in POST1, the database must contain the same model for which the solution was calculated. Also, the results file (Jobname.rmg or Jobname.rst) must be available.

Results from a harmonic magnetic analysis are complex and consist of real and imaginary components. To read either type of component (you cannot read both types at the same time), use either of the following:

Command(s): SET
GUI: Utility Menu> List> Results

An SRSS combination of the real and imaginary parts gives the true magnitude of the results. You can do this via load case operations.

7.3.2.1. Contour Displays

You can contour almost any result item (including flux density and field intensity) using the following commands or menu paths:

Command(s): PLNSOL, PLESOL
GUI: Utility Menu> Plot> Results> Contour Plot> Elem Solution
Utility Menu> Plot> Results> Contour Plot> Nodal Solution


Caution:   The PLNSOL command or its equivalent menu path average nodal contour plots for derived data, such as flux density and field intensity, at the nodes. Therefore, be sure to disallow averaging of data across material boundaries, using one of these methods:

Command(s): AVRES,2
GUI: Main Menu> General Postproc> Options for Outp


7.3.2.2. Tabular Listings

You can produce tabular listings of results data, either unsorted or sorted by node or by element. To sort data before listing it, use any of the following:

Command(s): ESORT, NSORT
GUI: Main Menu> General Postproc> List Results> Sorted Listing> Sort Nodes
Main Menu> General Postproc> List Results> Sorted Listing> Sort Elems

To produce tabular data listings, use any of the following:

Command(s): PRESOL, PRNSOL, PRRSOL
GUI: Main Menu> General Postproc> List Results> Element Solution
Main Menu> General Postproc> List Results> Nodal Solution
Main Menu> General Postproc> List Results> Reaction Solu

7.3.2.3. Calculating Other Items of Interest

You can calculate many other items of interest (such as global forces, torque, source input energy, inductance, flux linkages, and terminal voltage) from the data available in the database in postprocessing. The Mechanical APDL command set supplies the following macros for these calculations:

For more discussion of these macros, see Electric and Magnetic Macros.