The program writes results from a harmonic magnetic analysis to the magnetics results file, Jobname.rmg (or to Jobname.rst if the electric potential (VOLT) or EMF degrees of freedom are active). Results include the data listed below, all of which vary harmonically at the operating frequency (or frequencies) for which you calculated the solution:
Primary data: Nodal DOFs (AZ, VOLT)
Derived data:
Nodal magnetic flux density (BX, BY, BSUM)
Nodal magnetic field intensity (HX, HY, HSUM)
Nodal magnetic forces (FMAG: components X, Y, SUM)
Nodal Lorentz magnetic forces (FMAG; components X, Y, SUM)
Nodal reaction current segments (CSGZ)
Total electric current density (JT)
Joule heat per unit volume (JHEAT)
Note: For nonlinear time-harmonic analysis, the values of flux density (B) may exceed the values input on the DC B-H curve. These values represent an approximation to the fundamental harmonic component of the true waveform, not the actual measurable value.
Additional data, specific to each element type, also are available. See the Element Reference for details.
You can review analysis results in POST1, the general postprocessor, or POST26, the time-history 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.
Use POST1 to review results over the entire model at specific frequencies. Use POST26 to review results at specific points in the model over the entire frequency range.
For a harmonic magnetic analysis, the frequency range usually consists of only the AC frequency. Therefore, POST1 is typically used to review the results.
To choose a postprocessor, use one of the following:
Several commands or GUI paths (see Table 3.5: Postprocessing GUI Paths and Commands) that are useful in postprocessing analysis results are listed below.
Table 3.5: Postprocessing GUI Paths and Commands
| Task | Command(s) | GUI Path |
|---|---|---|
| Select the real solution | SET,1,1,,0 | |
| Select the imaginary solution | SET,1,1,,1 | |
| Print vector potential DOF (AZ)[5] | PRNSOL,AZ | |
| Print time-integrated potential DOF (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 total current density at centroids[5] | PRVECT,JT | |
| Print force at corner nodes[2,6] | PRVECT,FMAG | |
| Print magnetic flux density at element nodes[5] | PRESOL,B | |
| 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 per unit volume[4,6] | PRESOL,JHEAT | |
| Create element table item for centroid flux density[5], X component. (Issue similar commands for Y and SUM components.) | ETABLE,Lab,B,X | |
| Create element table item for centroid magnetic[5] field, X component. (Issue similar commands for Y and SUM components.) | ETABLE,Lab,H,X | |
| Create element table item for Joule heat per unit volume[4,6] | ETABLE,Lab,JHEAT | |
| Create element table item for centroid current[5] density, X component. (Issue similar commands for Y 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 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,... |
Force is summed over elements and distributed among nodes for coupling purposes.
Instantaneous value (real/imaginary, at Ωt = 0 and Ωt = -90) in case of a harmonic analysis.
RMS value: measurable values are stored in the real set. (Velocity effect regions (KEYOPT(2) = 1) require summation of real and imaginary parts to obtain RMS value.)
The ETABLE command or its GUI path also allow 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):
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. See the Ansys Parametric Design Language Guide for more information about APDL. Electric and Magnetic Macros describes the macros.
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.
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:
An SRSS combination of the real and imaginary parts gives the true magnitude of the results. You can do this via load case operations.
You can contour almost any result item (including flux density and field intensity) using the following commands or menu paths:
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.
In PowerGraphics mode (default), you can visualize nodal averaged contour displays which account for material discontinuities. Should you need to activate PowerGraphics, use either /GRAPHICS,POWER ().
Vector displays (not to be confused with vector mode) offer an effective way to view vector quantities such as A, B, H, and FMAG. For vector displays, use either of the following:
For vector listings, use either method shown below:
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:
To produce tabular data listings, use any of the following:
Lorentz, Maxwell and virtual work force computations are usually available when using PLANE13:
Time-average Lorentz forces (the JxB forces) are calculated automatically for all current carrying elements. These forces are stored in the "real" data set (see SET command to retrieve "real" results). (Exercise caution in interpreting Lorentz forces in permeable (μr > 1 materials.) To list these forces, select all current-carrying elements and use either the PRNSOL,FMAG command or its equivalent menu path. You can also sum these forces. First, move them to the element table using either of the following:
GUI:Then, calculate the sum using either of the following:
Command(s): SSUMGUI:For velocity effect regions (KEYOPT(2) = 1), the time-average forces are obtained by summing the data stored in the "real" and "imaginary" data sets.
Time-average Maxwell forces are calculated for all elements at which the surface flag MXWF is specified as a surface "load." To list Maxwell forces, select all such elements, read in the "real" data set and then select either of the following:
Command(s): PRNSOL,FMAGGUI:To sum the forces, use the procedure described in the foregoing for Lorentz forces.
Note: For velocity effect regions (KEYOPT(2) = 1), the time-average forces are obtained by summing the data stored in the "real" and "imaginary" data sets.
Time-average virtual work forces are calculated for all air elements with an MVDI specification adjacent to the body of interest. To extract these forces, select all current-carrying elements and use the ETABLE command along with the sequence number (snum) for the data requested to store the forces from the element NMISC record (see PLANE13 Item and Sequence Numbers for ETABLE and ESOL in the Element Reference). Do so by choosing either of the following:
GUI:Once you move the data to the element table, you can list them using either of the following:
Command(s): PRETABGUI:To sum the forces, use the procedure described in the foregoing for Lorentz forces.
Note: For velocity effect regions (KEYOPT(2) = 1), the time average-forces are obtained by summing the data stored in the "real" and "imaginary" data sets.
For information on calculating magnetic forces when using PLANE233, see Older vs. Current 2D Magnetic Element Technologies.
Lorentz, Maxwell and virtual work torque computations are usually available when using PLANE13:
Time-average Lorentz torque (the JxB torque) is calculated automatically for all current carrying elements. These torque values are stored in the "real" data set (see SET command to retrieve "real" results). Exercise caution in interpreting Lorentz torque values in permeable (m r >1) materials.) To extract these torque values, select all current-carrying elements and use the ETABLE command along with the sequence number (snum) for the data requested to store the torque values from the element NMISC record (see PLANE13 Item and Sequence Numbers for ETABLE and ESOL in the Element Reference). Do so by choosing either of the following:
GUI:Once you move the data to the element table, you can list the torque values using the following command:
Command(s): PRETABGUI:The torque data can also be retrieved using the PLESOL and PRESOL commands with the NMISC item label.
You can also sum the torque values to obtain the total torque on the body. To calculate the sum use the following:
Command(s): SSUMGUI:Note: For velocity effect regions (KEYOPT(2) = 1), the time-average torque values are obtained by summing the data stored in the "real" and "imaginary" data sets.
Maxwell torque values are calculated for all elements at which the surface flag MXWF is specified as a surface "load." To extract and sum Maxwell torque values, you can use the procedure described in the foregoing for extracting and summing Lorentz torque values.
Note: For velocity effect regions (KEYOPT(2) = 1), the time-average torque values are obtained by summing the data stored in the "real" and "imaginary" data sets.
Time-average virtual work torque values are calculated for all air elements with an MVDI specification adjacent to the body of interest. To extract and sum virtual work torque values, you can use the procedure described in the foregoing for extracting and summing Lorentz torque values.
Note: For velocity effect regions (KEYOPT(2) = 1), the time-average torque values are obtained by summing the data stored in the "real" and "imaginary" data sets.
For information on calculating magnetic torques when using PLANE233, see Older vs. Current 2D Magnetic Element Technologies.
For stranded coils with the voltage-fed or circuit-fed options, you can
calculate the resistance and inductance of the coil. Each element stores values
of resistance and inductance. Summing these values gives the total resistance
and inductance of the modeled region of the conductor. To store and sum these
values, select the conductor elements using the
ETABLE,tablename,NMISC,n
command or its equivalent menu path. (For the n value, use 8 for resistance and 9 for inductance.) Use the
SSUM command or its menu path equivalent to sum the
data.
Inductance values calculated for voltage-fed or circuit-coupled stranded coils are only valid under the following conditions:
The problem is linear (constant permeability).
There are no permanent magnets in the model.
Only a single coil exists in the model.
You can calculate many other items of interest (such power loss and eddy currents) from the data available in the database in postprocessing. The Mechanical APDL command set supplies the following macros for these calculations:
The EMAGERR macro calculates the relative error in an electrostatic or electromagnetic field analysis.
The FLUXV macro calculates the flux passing through a closed contour.
The MMF macro calculates magnetomotive force along a path.
The PLF2D macro generates a contour line plot of equipotentials.
The POWERH macro calculates the rms power loss in a conducting body. Time-average (rms) power loss represents the Joule heating losses. The program calculates it from real and imaginary total current density when you use the following command macro or GUI path:
Command(s): POWERHGUI:
For heat transfer coupling, the power loss term is expressed in terms of Joule heat generation rate. You can use it in a thermal analysis; to do so, read the data from the magnetics results file using the LDREAD command ().
The SENERGY macro determines the rms stored magnetic energy or co-energy.
For more discussion of these macros, see Electric and Magnetic Macros.
For information on the macros applicable to PLANE233, see the element's description in the Element Reference.