1. Chapter 5 Armature Gap Sweep Workshop 4

2. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-2 Workshop #2: Armature Gap Sweep A DC solenoid consists of a coil wrapped around a permeable “U” shaped body and an armature. The position of the armature is swept in a series of analyses to determine forces acting on both the body and the armature as a function of the air gap. Coil self-inductance is also calculated and used in an alternate evaluation of force using: F = (½)i 2 (dL/dx) where, F = armature force (N) i = coil current (A) L = coil self-inductance (H) x = coil position (m) Armature or keeper Body Coil Force acting on keeper Air gap WS04: Armature Gap Sweep

3. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-3 Upon entering the workbench environment, choose new geometry. 1 WS04: Armature Gap Sweep

4. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-4 Change the desired unit length to millimeters. 1 2 WS04: Armature Gap Sweep

5. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-5 Read in the cad geometry file base.iges and click on “generate”. This geometry will, by default, use the global XYPlane as its base plane (its position will be with respect to a fixed, unmovable coordinate system). 1 2 4 3 WS04: Armature Gap Sweep

6. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-6 Create a new plane. The new plane will automatically be named Plane4 and appear in the tree. Click on Generate to create Plane4. Unlike global planes, the location and orientation of Plane4 may be changed and parameterized. Ensure that Plane4 is the active plane after it is created. 1 2 Plane4 is the active plane if its name appears here WS04: Armature Gap Sweep

7. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-7 Next, read in the cad geometry file keeper.iges and click on “generate”. Since Plane4 is the active plane, it will be assigned as the base plane to the keeper (the keeper position will be defined with respect to Plane4). And since Plane4 may be repositioned, its coordinates may be used to parameterize the position of the keeper. 1 2 3 WS04: Armature Gap Sweep

8. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-8 Offset the x coordinate of Plane4 as shown. Specify the offset to be -5 mm and declare the offset to be a parameter named ds_gap. Click on Generate to see the keeper move 5 mm away from the body. 1 (RMB) 2 3 4 5 7 6 8 WS04: Armature Gap Sweep

9. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-9 Bring up the active parameters window. You may edit the value of ds_gap in the window and click Generate to see how the change affects the keeper position. For example, change the value of ds_gap to -25 and click Generate. When you are done experimenting, change the value of ds_gap back to -5 and click generate. 3 2 1 ds_gap = -25 WS04: Armature Gap Sweep

10. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-10 Activate the XYPlane and bring up the Winding Tool. 1 2 WS04: Armature Gap Sweep

11. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-11 In the Details window, click on the apply button adjacent to “Center Plane”. This declares that winding geometry will be defined with respect to the currently active global XYPlane. Next, click on the box adjacent to Winding Table File. Click on the browser button (“…”) and browse for kpr_sweep.txt. Open the file to read in the coil geometry and click on Generate. 4 3 2: Click on box to the right of Winding Table File to bring up browser button (“…”). Click the browser button. 1 5 WS04: Armature Gap Sweep

12. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-12 You can visualize the coil cross section geometry define by the fields in the winding table by activating “Show Cross Section Solids”. 1 WS04: Armature Gap Sweep

13. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-13 Bring up the enclosure tool. Increase the default “cushion” of 30 mm to 50 mm. VERY IMPORTANT! Change “Merge Parts” field to “yes”, otherwise the model will not solve (you will get an “invalid geometry message when attempting to do so). Click on Generate to create the enclosure. 2 3 1 3 CHANGE TO YES! WS04: Armature Gap Sweep

14. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-14 Save the geometry to swp_keeper.agdb. 1 2 3 WS04: Armature Gap Sweep

15. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-15 Click on the Project tab and choose “New Simulation”. 1 2 WS04: Armature Gap Sweep

16. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-16 Open “Geometry” in the tree on the left. Left click on any of the items labeled “solid” to see which part it represents (it will appear a solid green color in the plot). Right click on any of these items to produce the drop-down menu shown at right. Choose “Rename” and rename the parts as shown in the inset. 1 (RMB) 2 WS04: Armature Gap Sweep

17. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-17 To prepare for assigning flux parallel boundaries on the exterior of the air, hide all other bodies. 1 (RMB) 2 WS04: Armature Gap Sweep

18. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-18 Insert flux parallel boundary conditions as shown. 1 (RMB) 2 3 WS04: Armature Gap Sweep

19. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-19 Activate face select mode. Hold down the CTRL button and use the LMB to select the three external surfaces facing you. Use the middle mouse button to rotate the geometry so the other three surfaces are facing you. Hold down the CTRL button and use the LMB to add them to the set to be made flux parallel. Click apply. 1 2 WS04: Armature Gap Sweep

20. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-20 Define the per-turn current in the conductor to be 5 A as shown. 1 2 WS04: Armature Gap Sweep

21. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-21 Declare the keeper/body airgap to be a parameter. Click on “Geometry” in the tree and check the box to the left of ds_gap in “Details”. 1 2 1 2 WS04: Armature Gap Sweep

22. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-22 Insert a request for calculations of total flux density. 1 (RMB) 2 WS04: Armature Gap Sweep

23. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-23 Insert a request for calculations of directional force/torque. 1 (RMB) 2 WS04: Armature Gap Sweep

24. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-24 Assign the directional force/torque request to the keeper. Use the same procedure to define an additional request for x component forces on the body. 1: Click on box to the right of “Geometry” to bring up Apply/Cancel buttons. 2: Body pick mode 3 Select keeper 4 Apply to accept 5 Request force in x direction WS04: Armature Gap Sweep

25. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-25 Highlight the first Directional Force/Torque request in the tree. In “Details” click the box adjacent to Sum. This will parameterize the calculated net values of keeper force. Do the same for the second directional force/torque request (to parameterize the net force on the body). 1 2 WS04: Armature Gap Sweep

26. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-26 Insert a request for a coil self- inductance calculation as shown. 1 2 3 WS04: Armature Gap Sweep

27. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-27 Define the mesh controls. Use advanced global control with a proximity setting of 75 and a gap distance of 0.010 m. 1 2 3 4 WS04: Armature Gap Sweep

28. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-28 Create the 0.010 m gap sizes. The 2 gaps that Simulation recognized in the active geometry can be graphically displayed by clicking on them in the tree. As you do this, change the gap aspect ratio to 1:1 in “Details” for both of the gaps. 1 2 3 4 WS04: Armature Gap Sweep

29. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-29 Generate the mesh. 1 (RMB) 2 WS04: Armature Gap Sweep

30. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-30 Insert the parameter manager as shown. 1 (RMB) 2 3 WS04: Armature Gap Sweep

31. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-31 Note that a single case is defined – one in which ds_gap = -5 mm. It is not possible to add parameterize inductance prior to solving, so we will solve this single case, then add the parameter for inductance to the parameter manager. 2 1: note single case defined WS04: Armature Gap Sweep

32. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-32 After the run is complete (~5 minutes) check the box to the left of the reported value of inductance. This will parameterize it and add it to the parameter manager. 2 1 WS04: Armature Gap Sweep

33. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-33 Returning to the parameter manager, note that the coil inductance has been added to the table. Right click anywhere on the row in the table and click on “add” to add additional rows. Add 2 more rows, one with ds_gap = -4.5 and another with ds_gap = -5.5. Leave the box at the far left end unchecked for Run #1 but check the boxes for the 2 newly defined cases. Clicking Solve will run both of these newly defined cases sequentially. 2 1 3 WS04: Armature Gap Sweep

34. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-34 After the 2 new runs have finished, an alternative evaluation of armature force can be obtained by considering the derivative of the inductance with respect to its position. Using the 2 positions straddling ds_gap = -5 mm, the force is 467.4 N (see calculation below). F body = -452.6 N F keeper = 446.8 N F inductance = 467.4 N The force from inductance considerations is: F = (½)i 2 (dL/dx) = (0.5)(5 A) 2 (0.53442 – 0.49703)H/(0.001m) = 467.4 N (compare with 0.0837 N obtained with the magnetic virtual displacements method) WS04: Armature Gap Sweep

35. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-35 Graphs of the data can be created by inserting a variable graph. 1 (RMB) 2 3 WS04: Armature Gap Sweep

36. Training Manual Electromagnetic Analysis in Workbench March 4, 2005 Inventory #002210 5-36 Chose the variables assigned to the x and y axes. 1 2 WS04: Armature Gap Sweep