9.0 new features low frequency electromagnetic analysis of motors workbench 5 lf emag in workbench

9.0 New Features

Low Frequency Electromagnetic Analysis of Motors

Workbench 5

LF Emag in Workbench

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

WS5-2© 2004 ANSYS, Inc.

Motor Analysis in the Workbench Environment

Upon entering the workbench environment, read in the design modeler geometry stored in motor2_base.agdb.

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You should see an end view of the motor geometry. Using the left mouse button (LMB) click on the blue dot adjacent to the triad in the lower right corner of the plot. This should result in the isometric view shown at right.

The image can be dynamically rotated as follows:

1) Position the mouse cursor on the display

2) Hold down the middle mouse button (MMB)

3) Move the mouse cursor

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1) Bring up the enclosure tool as shown at right. This will be used to automatically create a mesh of the magnetic domain between and surrounding the imported geometry

2) Note the details that appear in the lower left pane after this selection is made. We will edit these default values.

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Click on the individual entries in the right hand column of the details pane and edit them as shown below.Enclosure name changed to “Air”

Shape: Cylinder

Alignment: Automatic

Cushion: 8 mm

Target: All Bodies

Merge Parts?: Yes

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After editing the details, right click on “Air” in the tree. In the drop down list that appears, left click on “Generate”. This will create a cylindrical volume of magnetic domain in which to immerse the imported parts.

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In the tree, open the item “1 Part, 5 Bodies” by clicking on the “+” symbol to the left of it. Do the same with the item labeled “part” that appears below it. Note that the single part in the model consists of 5 individual bodies (stator, rotor, magnet1, magnet2, and “solid”).

Right click on “solid” and in the drop down menu, request that it be hidden in the display. Note that the display of any individual bodies may be either suppressed or restored in this manner.

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Use the Winding Tool Editor to bring up the “winding details” and “winding table” panes shown in the red boxes at right.

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In the winding details pane, click on the cell to the right of “Center Plane”, then select Plane6 from the tree, then click apply (step 3 at right). This positions/orients the windings so that predefined plane6 is the winding midplane.

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3: Click “Apply”

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A winding table text file containing information describing the rotor coils (winding.txt) is in the local working directory. Read the table as shown at right. Click the cell to the right of “winding Table File” in the winding details pane and click on “…” to browse for the file.

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Once the file is read in, make the following additional changes in the winding details pane:

• FD2: Slot Angle => 22.5

• Clash Detection? => Yes

Setting clash detection to “yes” will bring up another row called “Bodies for Clash Detection” in the winding details pane. Click the cell to the right, highlight “rotor” in the tree, and click Apply. This will trigger a check for interference between the defined windings and the rotor stack.

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4: Click “Apply”1

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After the winding specifications have been defined, create the winding by right clicking on “Winding” in the tree and left clicking on “Generate” in the drop down list.

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One nice way to visualize the windings is to right click on rotor in the tree and choose “Hide All Other Bodies” in the drop down list. Then, in the tree, click on any of the 6 individual coils comprising the winding (A.1, A.2, B.1, B.2, C.1, C.2). For example, the location of coil A.1 is shown below.

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Now click on the Project tab and choose “New Simulation”

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Once the geometry is successfully attached in Design Simulation, define the current and phase angles for conductors A, B, and C as shown at right:

Conductor A: 55 A 0

Conductor B: 55 A 120

Conductor C: 55 A 240

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Prepare to define magnetic flux parallel boundaries on the exterior of the modeled domain as shown at right.

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In order to more easily select the external surfaces of the modeled domain, suppress all bodies except “Solid”. For example, suppression of the stator body is illustrated at right. Right click on each body to be suppressed to bring up the drop down menu.

When you are done, only the “Solid” body should remain unsuppressed (have a “” adjacent to it rather than an “x”).

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To define flux parallel surfaces, select “Magnetic Flux Parallel” from the tree and click on the cell adjacent to “Geometry” in the magnetic flux details pane.

Position the mouse cursor on any of the surfaces bounding the cylindrical volume and click with the left mouse button. After selecting the first surface, hold down the control button and select another. If necessary, release the Ctrl button, use the MMB to reorient the model as needed, and select the third (and final) surface.

Click “Apply” in the magnetic flux parallel details pane.

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3: Select external surfaces of cylinder using Ctrl + LMB

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Right click on any of the bodies in the tree and select “Unsuppress All Bodies”.

Select “Rotor” from the tree and in the details pane, click on the arrow in the cell to the right of “Material”. From the drop down list, choose “Import”.

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Make the selections shown in the “Import Material Data” dialogue box as shown at right. This will simultaneously import the BH curve for M14 steel into the database and assign this property to the rotor body.

You may view the BH data (table and xy plot) by clicking on the arrow in the cell to the right of “Material” in the details pane and selecting “Edit M14 Steel” in the drop down list (see next slide).

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4: Select “Edit M14 Steel” from the drop down list

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Click on the thumbnail sketch in the right hand pane to display the xy plot shown at right. Click on the Simulation tab to return to the model.

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Click on “Stator” in the tree. In the Stator details pane, click on the arrow in the cell to the right of “Material” and choose “M14 Steel” (this material property is now an active part of the database) from the drop down list.

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Initiate the creation of a new material property for body “Magnet1” as shown at right.

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Click on “Add/Remove Properties” in the Electromagnetics section. In the “Add or Remove Properties” dialogue box, choose “Linear Hard Magnetic Material”.

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Define the coercivity and remanant magnetization:

Hc = 750000 A/m

Br = 0.6 T

It may also be necessary to supply a “dummy” value for Young’s Modulus to workaround unnecessary error trapping.

Right click on “New Material”, select “Rename” from the drop down list, and change the name of the new material to “PM”.

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Click on the Design Simulation tab.

Click on the “Magnet2” body in the tree.

Click on the arrow in the cell to the right of “Material” in the magnet2 details pane and choose “PM”

We have now assigned PM properties to both magnets but have yet to define their polarity. They will be radially poled. The upper magnet (Magnet1) will be poled radially outward (“+x” in a cylindrical coordinate system) while the lower PM will be poled radially inward (“-x” in cylindrical coordinates).

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Initiate the creation of a cylindrical coordinate system.

Click on “Model” in the tree.

Choose “Insert” from the first drop down list.

Choose “Coordinate System” from the second drop down list.

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Click on “Coordinate Systems” in the tree. Note: make no attempt to modify predefined “Global Coordinate System”.

Click on “Insert” and “Coordinate Systems” in the cascading drop down lists as shown at right.

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Right click on “Coordinate System” in the tree and choose “Rename” from the drop down list. Rename the coordinate system as desired (for example, “PM_CSYS”, as shown at right).

Click on the cell to the right of “Type” in the PM_CSYS details pane and change to Cylindrical.

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Select “Magnet1” in the tree and assign to it the “PM_CSYS” coordinate system with “+x” polarization in the magnet1 details pane.

Do the same for “Magnet2” except set the polarity in the “–x” direction.

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Select “Mesh” from the tree. In the mesh details pane, establish the following settings:

Global Control => Advanced

Curve/Proximity => 40

Gap Distance: 7e-4 m

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Request the automatic detection of surfaces within 7e-4 m. This will allow further specifications to be made on surfaces found to be within this tolerance (next slide).

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In the tree, select all surface pairs having a proximity of 7e-4 m (click “Gap Sizing” then hold down the shift key and select “Gap Sizing 6”).

Set the Gap Aspect Ratio in the details pane to 3.

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Create the mesh

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If you wish to view the mesh of an individual body, select it (right mouse button) in the tree, click on “Hide All Other Bodies” in the drop down list, and click on “Mesh” in the tree. The rotor mesh is shown below.

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Add a request for calculated values of “Total Flux Density” on all bodies (the default).

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Add a request for calculated values of “Directional Force/Torque”.

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Set “Orientation” in the details pane to “Z Axis” (i.e., calculate torque about the global z axis).

Click on the cell to the right of “Geometry” in the details pane and left click in the vicinity of the rotor centroid. You will see a number of “sheets” appear in the display. Left click on these one at a time until you find the one associated with the rotor (the rotor will be highlighted in green as shown at right).

Click “Apply” as shown. The rotor should be displayed in a dark blue color.

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3: Click around here

4: Cycle through “sheets” until the rotor is highlighted in green

5: Click Apply

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We have specified nonlinear BH data for the rotor and stator but will suppress its usage so that the solution can be obtained expediently. Choose “Rotor” in the tree and set “Nonlinear Material Effects” to “No” in the rotor details pane. Do the same for the stator (shown at right). 1

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Execute the linear solution as shown at right.

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One the solution has completed (~10-15 minutes), you may select an individual body for postprocessing. For example, to view results on the rotor, right click on it in the tree and click on “Hide All Other Bodies” in the drop down list. 1

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Selecting “Total Flux Density” in the tree produces a contour plot of the magnitude of the B field in the unhidden part(s).

The B field may also be plotted as vectors by clicking on the vector graphics button. This button toggles between contour and vector displays.

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2: Access vector plot representation

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You may also experiment with the vector plot controls. Vectors may be “element aligned” (one per element) or “grid aligned” (displayed with a user selected density). Length may be scaled for better visibility. The wire frame button makes the body transparent so that the vectors within the volume of the body may be visualized.

Magnitude scaled3D arrows

Wireframe Display

Grid aligned

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A contour of the z component magnetic forces and net rotor torque about the global z axis may be produced as shown at right.

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Net Torque

9.0 new features low frequency electromagnetic analysis of motors workbench 5 lf emag in workbench

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