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Maxwell v11 Transient Getting Started with Maxwell: Transient Problem June 2005 The information contained in this document is subject to change without notice. Ansoft makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Ansoft shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material. © 2005 Ansoft Corporation. All rights reserved. Ansoft Corporation 225 West Station Square Suite 200 Pittsburgh, PA 15219 USA Phone: 412-261-3200 Fax: 412-471-9427 Maxwell and Optimetrics are registered trademarks or trademarks of Ansoft Corporation. All other trademarks are the property of their respective owners. New editions of this manual will incorporate all material updated since the previous edition. The manual printing date, which indicates the manual’s current edition, changes when a new edition is printed. Minor corrections and updates that are incorporated at reprint do not cause the date to change. Update packages may be issued between editions and contain additional and/or replacement pages to be merged into the manual by the user. Pages that are rearranged due to changes on a previous page are not considered to be revised. Edition 1 Date June 2005 Software Version Maxwell 11 Getting Started with Maxwell: Transient Problem Conventions Used in this Guide Please take a moment to review how instructions and other useful information are presented in this guide. • The project tree is the main project area of the Project Manager win- dow. These two terms (project tree and Project Manager window) and may be used interchangeably in this guide. • Procedures are presented as numbered lists. A single bullet indicates that the procedure has only one step. • Bold type is used for the following: - Keyboard entries that should be typed in their entirety exactly as shown. For example, “copy file1” means to type the word copy, to type a space, and then to type file1. - On-screen prompts and messages, names of options and text boxes, and menu commands. Menu commands are often separated by carats. For example, click Maxwell>Excitations>Assign>Voltage. Alternate methods or tips are listed in the left margin in blue italic • text. • - Labeled keys on the computer keyboard. For example, “Press Enter” means to press the key labeled Enter. Menu commands are often separated by the “>” symbol. For example, “Click File>Exit”. Italic type is used for the following: - Emphasis. - The titles of publications. - Keyboard entries when a name or a variable must be typed in place of the words in italics. For example, “copy file name” means to type the word copy, to type a space, and then to type a file name. • The plus sign (+) is used between keyboard keys to indicate that you should press the keys at the same time. For example, “Press Shift+F1” means to press the Shift key and the F1 key at the same time. • Toolbar buttons serve as shortcuts for executing commands. Toolbar buttons are displayed after the command they execute. For example, “On the Draw menu, click Line ” means that you can also click the Draw Line toolbar button to execute the Line command. iii Getting Started with Maxwell: Transient Problem Getting Help Ansoft Technical Support To contact Ansoft technical support staff in your geographical area, please log on to the Ansoft corporate website, http://www.ansoft.com, click the Contact button, and then click Support. You will find phone numbers and e-mail addresses for the technical support staff. Your Ansoft account manager may also be contacted in order to obtain this information. All Ansoft software files are ASCII text and can be sent conveniently by email. When reporting difficulties, it is extremely helpful to include specific information about what steps were taken or what stages the simulation reached. This allows more rapid and effective debugging. Context-Sensitive Help To access online help from the Maxwell user interface, do one of the following: • To open a help topic about a specific Maxwell menu command, press Shift+F1, and then click the command or toolbar icon. • To open a help topic about a specific Maxwell dialog box, open the dia- log box, and then press F1. iv Table of Contents 1. Introduction Setting Up Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 About the Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 2. Setting Up the Design Open Maxwell and Save a New Project . . . . . . . . . . . . . . 2-2 Specify a Solution Type . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 Set the Drawing Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 3. Creating the Geometry Model Create the Outer Armature Object . . . . . . . . . . . . . . . . . . . 3-2 Create the Inner Armature Object . . . . . . . . . . . . . . . . . . . 3-6 Create the Coils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 Move the coil into the final position: . . . . . . . . . . . . . . . . . 3-9 Create a mirror duplicate of the coil: . . . . . . . . . . . . . . . . . 3-9 Create the Coil Terminals . . . . . . . . . . . . . . . . . . . . . . . . . 3-9 Create the Background (Region) . . . . . . . . . . . . . . . . . . . . 3-9 Finalize the Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10 4. Defining Material Properties, Excitations, and Mesh Operations Define Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Contents-1 Getting Started with Maxwell: Transient Problem Define the Nonlinear Material for the Two Armatures . . . 4-2 Assign Material Properties . . . . . . . . . . . . . . . . . . . . . . . . 4-3 Assign Excitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 Set Up the External Circuit . . . . . . . . . . . . . . . . . . . . . . . . 4-5 Set Up Mesh Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 Specify the Eddy Effect Calculation . . . . . . . . . . . . . . . . . 4-9 5. Setting Up and Running the Analysis Set up the Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 Running the Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 6. Post Processing the Results Plot the Magnetic Flux Density Vector . . . . . . . . . . . . . . . 6-2 7. Including Motion in the Simulation Add Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 Add a Band Object to the Design . . . . . . . . . . . . . . . . . . . 6-2 Post Process the Transient Results . . . . . . . . . . . . . . . . . 6-4 Close the Project and Exit Maxwell . . . . . . . . . . . . . . . . . . 6-8 8. Appendix: Understanding the Maxwell Interface A. Desktop Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 B. Using Mouse Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 C. Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 Contents-2 1 Introduction Estimated time to complete this guide: 45 minutes. Maxwell® 3D is an interactive software package that uses finite element analysis (FEA) to simulate (solve) electromagnetic field problems. Maxwell integrates with other Ansoft software packages to perform complex tasks while remaining simple to use. The following types of solutions are supported by Maxwell 3D: Electric 3D fields, which can be one of the following two categories: • Electrostatic 3D fields caused by user-specified distribution of voltages and charges; additional computed quantities include torque, force, capacitances as indicated by the user. • Electric 3D fields in conductors characterized by a spatial distri- bution of voltage, electric field and current density; additional quantity in this case is power loss. Magnetostatic linear and non-linear 3D fields caused by user-specified distribution of DC current density, permanent or externally applied magnetic fields; additional computed quantities include torque, force, inductances (self and mutual) as indicated by the user; Harmonic (sinusoidal variation in time) steady state magnetic fields with pulsation-induced eddy currents in massive (solid) conductors caused by a user specified distribution of AC currents (all with same frequency but with possibly different initial phase angles) or by externally applied magnetic fields; this is a full wave solution and includes electromagnetic wave radiation; Introduction 1-1 Getting Started with Maxwell: Transient Problem See the online help about the specific parameter you want to vary to determine if it can be assigned a variable. Transient (time domain) magnetic fields caused by permanent magnets, conductors and windings supplied by voltage and/or current sources with arbitrary variation as functions of time; rotational or translational motion effects can be included in the simulation. The application described in this getting started guide is an extension of TEAM Workshop Problem 24, which is a rotational actuator design. Results presented correspond to the simulation of a 3D electromagnetic time-transient problem with effects of large motion included in the simulation. Both the rotor and the stator are made of solid ferromagnetic steel, creating significant eddy current effects. A nonlinear B-H curve for the stator and rotor steel is considered. Estimated mechanical inertia of the rotor is included in the solution. The results of the simulation with different FEM code are presented in IEEE Transactions on Magnetics, Vol 38, No. 2, March 2002, pp 609-612. By following the steps in this guide, you will learn how to perform the following tasks: Draw a geometric model. Modify a model’s design parameters. Assign variables to a model’s design parameters. Specify solution settings for a design. Validate a design’s setup. Run a Maxwell simulation. Plot the magnetic flux density vector. Run a parametric analysis. 1-2 Introduction Getting Started with Maxwell: Transient Problem Setting Up Designs In Maxwell 11, you are no longer required to follow a specific order when setting up your Maxwell design. However, the following order is recommended, particularly for new Maxwell users: 1 Open Maxwell, and save a new project. 2 Draw the geometry of the model. 3 (Optional) If necessary, modify the model's design parameters. 4 Assign variables to design parameters. 5 Specify solution settings. 6 Run a Maxwell simulation. 7 Create post-processing plots. 8 Create a parametric analysis. 9 Create a field animation of the parametric analysis results. Introduction 1-3 Getting Started with Maxwell: Transient Problem About the Design The geometry for the TEAM Workshop Problem 24 rotational actuator is shown below. The outer part consists of a ferromagnetic nonlinear armature carrying two coils. The inner part is composed of the same nonlinear material and can rotate around an axis. The inner and outer parts of the device are co-axial. The field distribution is expected to cause the flux density to a concentrate in the two steel armatures in the regions where the distance between them is minimal. The expected edge effect will then further increase the field concentration. The torque acting on the inner armature and the flunk linkage of the two coils will also be computed in this example. 1-4 Introduction 2 Setting Up the Design In this chapter you will complete the following tasks: Open and save a new project. Insert a new Maxwell design into the project. Select a solution type for the project. Set the drawing units for the design. Estimated time to complete this chapter: 2 minutes. Setting Up the Design 2-1 Getting Started with Maxwell: Transient Problem Open Maxwell and Save a New Project A project is a collection of one or more designs that is saved in a single *.mxwl file. A new project is automatically created when Maxwell is launched. Open Maxwell, add a new design, and save the default project with a new name. To save your proNjeoctte frequently, click File>Save. . If you have already completed the magnetostatic example in the Getting Started with Maxwell: Designing a Rotational Actuator guide, you can open the existing Rotational_actuator project rather than creating a new one. 1 2 3 The current design has the default name 4 MthaexPwreoljleMcot dMeal1naligseterdwiinn-5 dow. You can change it by right-clicking it, select- ing Rename command, and entering a new name for it. You can add addi- tional designs to the project by repeating step 2 above, or by clicking the corresponding icon on the toolbar. For the current simulation task, we do not need to create additional designs. Double-click the Maxwell 11 icon on your desktop to launch Maxwell. Click Project>Insert Maxwell Design . The new design is listed in the project tree and is named MaxwellModeln by default. The 3D Modeler window appears to the right of the Project Manager. Click File>Save As. The Save As window appears. Locate and select the folder in which you want to save the project Type Rotational_actuator in the File name box, and click Save. 2-2 Setting Up the Design Getting Started with Maxwell: Transient Problem The project is saved in the specified folder under the name Rotational_actuator.mxwl. Project Manager Window Note The current design has the default name MaxwellModel1 listed in the Project Manager window. You can change it by right-clicking it, selecting Rename, and entering a new name. You can add additional designs to the project by repeating step 2 above or by clicking the corresponding icon on the toolbar. For this simulation example, we do not need to create additional designs. Setting Up the Design 2-3 Getting Started with Maxwell: Transient Problem Specify a Solution Type As mentioned in the introduction to this getting started guide multiple types of Maxwell 3D solutions are possible to choose from depending on the specific application. For this design choose a Transient type of solution. 1 Click Maxwell>Solution Type from the menus. The Solution Type dialog box appears. 2 Select Transient. 3 Click OK. Set the Drawing Units 1 Click 3D Modeler>Units. The Set Model Units dialog box appears. 2 Select mm from the Select units pull down menu. 3 Click OK. 2-4 Setting Up the Design 3 Creating the Geometry Model In this chapter you will complete the following tasks: Create the outer armature of the actuator by subtracting and uniting objects. Create the inner armature of the actuator. Create the coils. Create the coil terminals. Create the background object. Estimated time to complete this chapter: 40 minutes. Creating the Geometry Model 3-1 Getting Started with Maxwell: Transient Problem Create the Outer Armature Object Before creating the outer cylinder, make sure that the XY drawing plane is selected and that 3D is selected as the movement mode. To create the outer cylinder: 1 Click Draw>Cylinder from the menus. The cursor changes to a small black box (Drawing mode). 2 Select the center of the cylinder by clicking at the (0,0,0) location (the origin of the coordinate system). 3 Enter 104.5 for the radius in the dX box (at the bottom of the screen), and click Enter. 4 Enter 25.4 for the height in the dZ box, and click Enter. The Properties window appears automatically, with the Attribute tab displayed. You can also access the properties window directly from an area in the Maxwell desktop. 5 Click OK. 6 Change the Name field value (currently Cylinder1) to Outer_arm. 7 To change the color of the cylinder to red: 3-2 Creating the Geometry Model Getting Started with Maxwell: Transient Problem a. Scroll down to the Color property, and click the Edit button. The Color palette window appears. b. Select one of the red shades from the Basic colors group, and click OK to return to the main Properties window. 8 To set the transparency to 0.6, click the button for the Transparent property, and enter 0.6 in the box, and click OK to close the Set Trans- A Linear step sweep type enables you to specify a linear range of values with a constant step size. parency dialog box and return to the main Properties window. 9 Click OK to close the Properties window. 10 In the history tree window, double-click the CreateCylinder field. The Properties window appears, with the Command tab displayed. 11 In this window, you can visualize the geometric data and edit it. Click OK when you are done making any desired edits. Repeat the procedure above to create another cylinder (named Cylinder_tool) with the same center and height as Outer_arm but with a radius of 83.1 mm. Next, subtract Cylinder_tool from Outer_arm. To subtract the second cylinder from the first: 1 Select both cylinders by clicking their names in the history tree (hold the Ctrl key down when selecting the second one). 2 Click 3D Modeler>Boolean>Subtract. 3 If necessary, move the Outer_arm object into the Blank Parts column and the Cylinder_tool object into the Tool Parts column, by selecting Use the Tab key to navigate between value fields (from X to Y to Z and from dX to dY to dZ). each object and using the arrows to move it. 4 Click OK. Add the two magnetic poles to the outer armature. First create a box, then move the box into the correct position, and use the Mirror command to create a duplicate of the box. Unite the three model objects, and subtract the a cylinder to arrive at the final shape. To create a box: 1 Select Box from the Draw menu. 2 Enter the box position (-13.0, 0, 0) in the X, Y, and Z fields at the bot- tom of the screen, and then press Enter. 3 Enter the box size (27.8, -40, 25.4) in the dX, dY, dZ fields, and then press Enter. The Properties window appears. 4 Click OK. Creating the Geometry Model 3-3 Getting Started with Maxwell: Transient Problem To move the box into position: View the design 1 Select the box object previously created (for example, click the respec- variations that will be tive name in the history tree window). solved in table format under the Table tab. 2 Select Edit>Arrange>Move. This enables you to 3 Enter (0, 0, 0) in the (X, Y, Z) fields as the origin of the move vector, visualize the design variations that will be and press Enter. solved and manually 4 Enter (0, -45, 0) in the (dX, dY, dZ) fields as the target point of the adjust sweep points if necessary. move vector, and press Enter. To create a duplicate of the box using mirroring: 1 Select the box previously created. 2 Select Edit>Duplicate>Mirror. For more information 3 Enter (0, 0, 0) in the (X, Y, Z) fields as coordinates for the anchor point about the other options on the mirror plane and press Enter. in the Setup Sweep Analysis 4 Enter (0, 1, 0) in the (dX, dY, dZ) fields as coordinates of target point of dialog box, see the the vector normal to the mirror plane and press Enter. online help. To unite the three objects in the model: 1 Select the three objects in the model from the history tree window (select Outer_arm first, then hold down the Ctrl key and select the boxes). 2 Select 3D Modeler>Boolean>Unite. Because the first selected object was Outer_arm, the final object name assigned by default is Outer_arm. The name of the objects can be easily changed if desired in the Properties window with the Attribute tab selected. To provide the final shape for the magnetic pole faces: 1 Create a cylinder with the center at (0, 0,0), a radius of 53.75, and a height of 25.4. 2 Select the Outer_arm object, then hold down the Ctrl key and select the cylinder. 3 Select 3D Modeler>Boolean>Subtract. The Subtract dialog box appears. 4 Make sure the Outer_arm object is in the Blank Parts column and the Cylinder1 object is in the Tool Parts column. 5 Click OK. 3-4 Creating the Geometry Model Getting Started with Maxwell: Transient Problem The Outer_arm object should look as shown below. To automatically expand the project tree when an item is added to the project: Click Tools>Options> General Options. Under Project Options, select Expand Project Tree on Insert. Creating the Geometry Model 3-5 Getting Started with Maxwell: Transient Problem Create the Inner Armature Object To draw the inner armature: 1 Create a cylinder named shaft, with the center at (0, 0, 0), a radius of 25.4 mm, and an axial length of 25.4 mm. 2 Create a cylinder named Inner_arm, with the center at (0, 0, 0), a radius of 38.1 mm, and an axial length of 25.4 mm. 3 Select Inner_arm, and then hold down the Ctrl key and select shaft. 4 Select 3D Modeler>Boolean>Subtract from the menu bar. The Subtract dialog box appears. 5 Make sure the Inner_arm object is listed in the Blank Parts column and the shaft object is listed in the Tool Parts column. 6 Click OK. Change the color and transparency of the newly created object as desired. Add the two magnetic poles to the inner armature. First create a box, then move the box into the correct position, and use the Mirror command to create a duplicate of the box. Unite the inner armature with the two boxes, and intersect it with a cylinder to arrive at the final shape. To create a box: 1 Select Box from the Draw menu. 2 Enter the box position (-12.7, 0, 0) using the X, Y, Z fields at the bottom of the screen (navigate with the Tab key from the X field to the Y field to the Z field), and press Enter. 3 Enter the box size (25.4, -20, 25.4) using the dX, dY, dZ value fields, and press Enter. The Properties window appears. 4 Click OK to validate. To move the box into position: 1 Select the box object previously created (for example, click the respec- tive name in the history tree window). 2 Select Edit>Arrange>Move. 3 Specify (0, 0, 0) in the (X, Y, Z) fields as the origin of the move vector, and press Enter. 4 Specify (0, -35, 0) in the (dX, dY, dZ) fields as the target point of the move vector, and press Enter. To create a duplicate of the box using mirroring: 1 Select the box previously created. 2 Select Edit>Duplicate>Mirror. 3-6 Creating the Geometry Model Getting Started with Maxwell: Transient Problem 3 Enter (0, 0, 0) in the (X, Y, Z) fields as coordinates for the anchor point on the mirror plane, and press Enter. 4 Enter (0, 1, 0) in the (dX, dY, dZ) fields as coordinates of target point of the vector normal to the mirror plane, and press Enter. To unite the inner armature object with the two boxes: 1 Select the three objects in the model from the history tree window (select Inner_arm first, then hold down the Ctrl key and select the two boxes). 2 Select 3D Modeler>Boolean>Unite from the menu bar. Because the first selected object was Inner_arm, the final object name assigned by default is Inner_arm. The name of the objects can be easily changed in the Properties window on the Attribute tab. To provide the final shape for the magnetic pole faces: 1 Create a cylinder with the center at (0, 0,0), a radius of 51.05, and a height of 25.4. 2 Select the Inner_arm object, and then hold down the Ctrl key, and select the new Cylinder2 object. 3 Select 3D Modeler>Boolean>Intersect. Creating the Geometry Model 3-7 Getting Started with Maxwell: Transient Problem Create the Coils First create a new coordinate system (CS1) such that in the new coordinate system the XY plane becomes a median plane of the model. To create the new coordinate system: 1 Select Coordinate System>Create>Relative CS>Offset from the 3D Modeler menu. 2 Enter the new origin (0, 0, 12.7) in the (X, Y, Z) boxes, and then press Enter. The coil(s) are created by sweeping the coil cross-section along a path. Do the following to create the path, the cross-section, and the coil: 1 Set the drawing plane to XZ. 2 Select Rectangle from the Draw menu. 3 Enter (-17, 0 -15.5) in the (X, Y, Z) boxes, for the rectangle position, and then press Enter. 4 Enter (34, 0, 31) in the (dX, dY, dZ) boxes, and press Enter. 5 Select the Edit>Select>Faces, and select the newly created rectangle by clicking on it in the 3D Modeler window. 6 Select 3D Modeler>Surface>Uncover Faces. 7 Change the name of the uncovered entity to path. 8 Set the drawing plane to YZ. 9 Select Rectangle from the Draw menu to draw the cross-section of the coil. 10 Enter (0, 0, 15.5) in the (X, Y, Z) boxes, for the rectangle position, and then press Enter. 11 Enter (0, 17, 24) in the (dX, dY, dZ) boxes, and press Enter. 12 Change the name of the newly created rectangle to coil1. 13 Select the path and the cross-section by selecting their names in the history tree window (hold down the Ctrl key for the second selection). 14 Select Sweep>Along Path from the Draw menu, and click OK to accept the defaults. 15 Click OK to create the coil The final coil shape has rounded outside corners. Using the new coordinate system CS1, do the following to achieve the final shape: 1 Create a cylinder at the origin with a radius of 43 mm and a height of 3-8 Creating the Geometry Model Getting Started with Maxwell: Transient Problem 17 mm. 2 Select the cylinder and the coil, and perform a Boolean intersection. Move the coil into the final position: 1 Select the coil by clicking its name in the history tree window. 2 Select Arrange>Move from the Edit menu. 3 Specify (0, 0, 0) in the (X, Y, Z) fields, for the origin of the move vector, and then press Enter. 4 Specify (0, 54.5, 0) in the (dX, dY, dZ) fields as the target point of the move vector, and press Enter. Create a mirror duplicate of the coil: 1 Select the coil by clicking its name in the history tree window. 2 Select Arrange>Move from the Edit menu. 3 Specify (0, 0, 0) in the (X, Y, Z) fields as the coordinates of the anchor point on the mirror plane, and then press Enter. 4 Specify (0, 1, 0) in the (dX, dY, dZ) fields as coordinates of target point of the vector normal to the mirror plane, and press Enter. Create the Coil Terminals To create the terminals for the coils: 1 Select the two coils by clicking their names in the history tree window. 2 Select Surface>Section from the 3D Modeler menu, specify XY as the section plane, and click OK. 3 Select Boolean>Separate Bodies from the 3D Modeler menu. This allows the separation of the inter-linked sheet objects created since the intersection of the XY plane with either coil created two terminals in each coil. 4 Select the two redundant terminals, one at a time (click each name in the history tree window), and then press the Delete key on the keyboard. Create the Background (Region) Define a region box with the origin at (-250, -250, -250) and the dimensions (500, 500, 500). Creating the Geometry Model 3-9 Getting Started with Maxwell: Transient Problem Finalize the Geometry To finalize the geometry: 1 Select the Inner_arm object. 2 Rotate it (use the Arrange>Rotate command on the Edit menu), speci- fying the Z axis in the global coordinate system, and an angle of +29.5 degrees). 3-10 Creating the Geometry Model 4 Defining Material Properties, Excitations, and Mesh Operations In this chapter you will complete the following tasks: Define material properties. Assign excitations. Set up the mesh operations. Estimated time to complete this chapter: 15 minutes. Defining Material Properties, Excitations, and Mesh Getting Started with Maxwell: Transient Problem Define Material Properties In the Properties window with the Attribute tab selected, material properties are already present, with a default property (vacuum) already assigned to objects. You can change the material property of any object as soon as the object is defined. Instead, in this guide, you will group all material definition and assignment together. Define the Nonlinear Material for the Two Armatures To define the nonlinear material to be used for the armatures, do the fol- lowing: 1 Select the Outer_arm object by clicking on its name in the history tree window. 2 Make sure the Attribute tab is selected. 3 In the Material row, click the value field in the Value column. 4 In the Select Definitions window, click the Add Material button. 5 Enter arm_steel in the Material Name box. 6 In the Relative Permeability row and the Type column, click the corre- sponding check box, and change the type from Simple to Nonlinear. 7 Select the BH Curve field in the Value column. 8 Append additional rows to the table as needed, and enter the H and B data from the table below in the respective columns. H (A/m) 1. 0 2. 4000 3. 8010 B (T) 0 1.413 1.594 4. 16010 1.751 5. 24020 1.839 6. 32030 1.896 7. 40030 1.936 8. 48040 9. 64050 10. 80070 11. 96080 1.967 2.008 2.042 2.073 4-2 Defining Material Properties, Excitations, and Getting Started with Maxwell: Transient Problem 12. 112100 2.101 13. 128110 2.127 14. 144120 2.151 15. 176150 2.197 16. 272230 2.24 17. 272230 2.325 18. 304260 2.37 19. 336290 2.42 20. 396000 2.5 9 Click OK when done entering the H and B values. 10 Click Validate, and then click OK to exit the Edit operation. 11 Click OK once more to validate the definition and close the Select Def- initions window. Assign Material Properties Select the Inner_arm object, and assign the newly defined arm_steel prop- erty. Select the two coils, and assign copper as the material property: To assign the material properties to the model objects: 1 Select the object by clicking its name in the history tree window. 2 Make sure the Attribute tab is selected. 3 In the Material row, click the field in the Value column. 4 Scroll through the library, and select the desired material property. 5 Click OK to assign the material and close the window. 6 Leave the material assignment for the region (background) unchanged. Defining Material Properties, Excitations, and Mesh Getting Started with Maxwell: Transient Problem Assign Excitations Currents need to be defined and assigned as excitations for the two coil terminals. To define the currents: 1 Select each terminal (one at a time) by clicking it in the history tree win- dow. 2 Right-click, and select Assign Excitation>Coil Terminal from the short- cut menu. 3 Enter 350 A in the Number of Conductors box. 4 Optionally, you can swap direction. 5 Click OK to validate the excitation and close the window. 6 Repeat steps 1-6 for the second terminal, making sure that the two ter- minal coils are connected in series. By default, all faces of the region box (background) are assigned with magnetic flux tangent boundary conditions. Therefore, no additional boundary conditions are required for this example problem. To add a winding: 1 Right-click in the model window, and select Assign Excitation>Add Winding. The Winding Definition window appears. 2 Enter a name in the Name box (or accept the default, such as Winding1). 3 Set the Type to External, and select the Stranded radio button. 4 Leave the Initial Current set at the default value of 0 (zero). Note In this application we are using an external circuit to supply the excitation to the coil. For this example, we also could have used a voltage type of excitation. 5 Click OK. To add a terminal for the winding: 1 Right-click the Winding1 name in the project tree, and then select Add terminals. 2 Select the two previously defined terminals by clicking on their names (while holding down the Shift key). 3 Click OK. In the project tree, the two terminals are moved beneath Winding1. 4-4 Defining Material Properties, Excitations, and Getting Started with Maxwell: Transient Problem The region box (background) will have by default all faces assigned with magnetic flux tangent boundary conditions. Thus for this problem no additional boundary conditions are needed. Set Up the External Circuit The driving circuit for the winding in this design consists of a voltage source in series with a resistor and with the winding. When complete, the circuit should look similar to the figure below. To set up the external circuit: 1 From the Windows taskbar, click Start>Ansoft>Maxwell>Maxwell Cir- cuit Editor. The Maxwell Circuit Editor opens. 2 Click Project>Insert Maxwell Circuit Design. Defining Material Properties, Excitations, and Mesh Getting Started with Maxwell: Transient Problem The circuit sheet appears. 3 Select the Components tab in the project tree window. 4 Add the circuit elements: a. Place the winding element on the sheet: In the project tree, under Maxwell Circuit Elements/Dedicated Elements, select the Winding element, and drag it onto the sheet at the desired location. Rightclick, and select Finish to place the component. To view the properties, click the component in the schematic window. In Properties window, change the DeviceName to Winding1, the same name you used when defining the winding in the Maxwell design. Click Draw>Rotate to position the winding vertically. Note In the schematic sheet, all the windings must use the same names that were defined for them in Maxwell in the previous section. b. Place a resistor on the sheet: In the project tree, under Passive Elements, select Resistor, and drag the resistor onto the sheet. Rightclick, and choose Finish to place it where desired. Double-click the symbol of the resistor, and change the value of the resistor, R, to 4-6 Defining Material Properties, Excitations, and Getting Started with Maxwell: Transient Problem 3.09 Ohms. Click OK when done. c. Place a voltage pulse: In the project tree, under Sources select a VPulse element (Pulse Voltage Source), drag it to the sheet, and then right-click and select Finish to place it onto the sheet. Double- click the source element symbol on the sheet, and then specify the characteristics of the source as follows: • V1 (Initial voltage) = 0 • V2 (Peak voltage) = 5.97 • Tr (Rise time) = 0.001 • Tf (Fall time) = 0.001 • Pw (Pulse width) = 1 • Period =1 Leave the other fields set to the default values, and click OK. 5 Connect the circuit elements in series: a. Click Draw>Wire. b. Click the respective terminals. c. When done, place the Ground symbol: Click Draw>Ground (or click the Ground symbol on the toolbar), place the Ground symbol on the sheet in a convenient location, right-click, and select Finish to place the symbol. d. To connect then the ground to the circuit, click Draw>Wire, and draw the final wire. Defining Material Properties, Excitations, and Mesh Getting Started with Maxwell: Transient Problem 6 Export the netlist: a. Click Maxwell Circuit>Browse Netlist. b. Click Netlist>Export. The Netlist Export dialog box appears. c. Select the folder where you want to save the external circuit file. d. Type trans_circ.sph in the File name box. e. Click Save. 7 Click File>Save, type a name, and click Save to save the Maxwell Cir- cuit Editor project. 8 Click File>Exit to close the Maxwell Circuit Editor program. 9 In Maxwell (which should still be open), assign the external circuit: a. Click Maxwell>Excitations>External Circuit>Edit External Circuit. The Edit External Circuit dialog box appears. b. Click Import Circuit. The Select File dialog box appears. c. Set Designer Net List Files (*.sph) from the Files of type pull-down list. d. Browse to the location where you saved the circuit, select it, and click Open to import it. 10 Click OK to close any open dialog boxes. 4-8 Defining Material Properties, Excitations, and Getting Started with Maxwell: Transient Problem Set Up Mesh Operations This example involves transient magnetic fields in the presence of massive (solid) conductors, creating eddy currents. To catch the effects with reasonable accuracy, a finer mesh is required in those objects because skin effects are part of an accurate transient solution. To seed the mesh to the desired density in the Outer_arm and Inner_arm objects: 1 Select the two objects from the history tree window. 2 Right-click in the 3D Modeler window, and select Assign Mesh Opera- tion>Inside Selection>Length Based. The Element Length Based Refinement dialog box appears. 3 Enter 10 in the Maximum Length of Elements box, and select mm as the units. 4 Leave the Restrict the Number of Elements check box cleared. 5 Click OK. This operation will refine the mesh at run-time before the transient problem solution begins. This mesh will be used for all time steps; therefore, the mesh density should be appropriate for the anticipated field behavior for the entire transient analysis. Specify the Eddy Effect Calculation Eddy effects can be calculated in objects with nonzero electric conductivity. To calculate eddy effects: 1 Click Maxwell>Excitations>Set Eddy Effects. Defining Material Properties, Excitations, and Mesh Getting Started with Maxwell: Transient Problem The Set Eddy Effect dialog box appears. 2 Select the check boxes for the Inner_arm and Outer_arm objects. 3 Click OK. 4-10 Defining Material Properties, Excitations, and 5 Setting Up and Running the Analysis In this chapter you will complete the following tasks: Set up the analysis. Run and solve the analysis. Estimated time to complete this chapter: 20 minutes. Setting Up and Running the Analysis 5-1 Getting Started with Maxwell: Transient Problem Set up the Analysis To set up the analysis: 1 Right-click the Analysis field in the project tree. A shortcut menu appears. 2 Select Add Solution Setup. The Solve Setup dialog box appears. 3 Click the General tab. 4 Type 0.04 in the Stop time box, and select s as the units. 5 Type 0.005 in the Time step box, and select s as the units. 6 To add a sweep: a. Click the Save Fields tab. b. Select Linear Step from the Type pull-down list to identify the type of sweep. c. Type 0.001 in the Start box. d. Type 0.056 in the Stop box. e. Type 0.005 in the Step Size box. f. Click Add Sweep. 7 Click OK. Running the Analysis To run the analysis: • Right-click the Analysis field in the project tree, and select Analyze. Once the analysis is complete, you can move onto the post processing. 5-2 Setting Up and Running the Analysis 6 Post Processing the Results In this chapter you will complete the following tasks: Plot the magnetic flux density vector. Close the project and exit Maxwell. Estimated time to complete this chapter: 15 minutes. Post Processing the Results 6-1 Getting Started with Maxwell: Transient Problem Plot the Magnetic Flux Density Vector Plot the flux density vector on the mid-vertical symmetry plane of the device. You should already have a relative coordinate system (CS1) containing the desired plot plane as a coordinate system plane. To prepare for the plot, create a list of objects (since we want the respec- tive results plotted in the two armatures only): 1 Select (by clicking in the history tree window) the Outer_arm and Inner_arm objects. 2 Click 3D Modeler>List>Create>Object List. The list of selected objects (Objectlist1) is added under the Lists in the history tree window. To set the time step for post processing: 1 Click View>Set Solutions Context. The Set View Context dialog box appears. 2 Select the desired solution setup from the Solution Name pull-down list. 3 Select a time step from the Time pull-down list. 4 Click OK. To perform the plot, follow these steps: 1 Change the rendering of both Outer_arm and Inner_arm to wireframe. 2 Select the RelativeCS1:XY plane under Planes in the history tree win- dow. 3 Right-click Field Overlays in the project management window, and select Fields>B>B_Vector. 4 Make sure the Quantity is B_Vector. As requested, Maxwell has modified the 5 6 In the Volume column, click Objectlist1. Click Done. T-junction geometry so 7 that the value of offset is 0.09 inches, or the 8 Double-click the legend. Click the Scale, Marker>Arrow, or Plots tabs if you need to change the optimal variable value. You can select a differ- scale, the size or spacing of the arrows. ent value of offset in the table, and then click Apply to modify the T-junction geome- try to that offset value. When you are done, click Revert to return the geometry to the optimal value. 6-2 Post Processing the Results Getting Started with Maxwell: Transient Problem The plot should look similar to the figure below: To plot the current density distribution on the same XP plane of CS1: 1 Select the plane, right-click in the 3D modeler window, and select Fields/J/Mag_J. 2 Specify the volume as Outer_arm. 3 Click Done to plot. Notice the partial penetration of the field in the stator of the device; the transient distribution of the current density shows significant skin effects. Varying global quantities as a function of time is a very important output from the transient analysis. Examples of such quantities of interest include currents and voltages, power loss, torque/force, flux linkage of windings, and induced voltages. Post Processing the Results 6-3 Getting Started with Maxwell: Transient Problem To create those plots: 1 Right-click Results in the project tree, and select Create Report. 2 Leave the Report Type set to Transient and the Display Type to Rect- angular Plot. 3 Click OK. 4 From the Solution pull-down list, select Winding1. 5 From the Category pull-down list, select Current. 6 Click the Add Trace button. 7 Click Done to display the plot. To create a plot of the torque as a function of time: 1 Right-click Results in the project tree, and select Create Report. 2 Leave the Report Type set to Transient and the Display Type to Rect- angular Plot. 3 Click OK. The Traces dialog box appears. 4 From the Solution pull-down list, select Torque1. 5 From the Category list, select Torque. 6 Click the Add Trace button. 7 Click Done to display the plot. 6-4 Post Processing the Results Getting Started with Maxwell: Transient Problem To close the plot (it will still be available to view later): • Click the X in the upper right corner of the plot window. Post Processing the Results 6-5 Getting Started with Maxwell: Transient Problem 6-6 Post Processing the Results 7 Including Motion in the Simulation In this chapter you will complete the following tasks: Include large motion in the simulation. Post process the transient results. Estimated time to complete this chapter: 15 minutes. Including Motion in the Simulation 7-1 Getting Started with Maxwell: Transient Problem Add Motion Before adding motion, save the without motion design and create a copy: 1 Save the transient without motion design. 2 Right-click the name of the design in the project tree, and select Copy. 3 To paste it into the same project folder, right-click the name of the project in the project tree, and select Paste. 4 Double click the name of the copy to make it the active design. Add a Band Object to the Design The band object is a regular polyhedron positioned so that it contains all rotating objects inside it. To add the band object: 1 Set the working coordinate system to CS1. 2 Create a regular polyhedron around the Z axis with the following prop- erties: You can also use the Design Properties command to add new variables. • Named band • Origin at (0, 0, -120) mm • Radius of 52.5 mm • 240 mm long • Its end faces coincide with the faces of the region box created at 3.5. 3 Create a cylinder called air_rotor with the following properties • Origin at (0, 0, -120) mm • Radius of 51.05 mm • 240 mm long • Contains the rotating part inside. • Assign it the material property of vacuum. The band object has its circumference between the inner armature and the outer armature and it contains inside it the air_rotor and Inner_arm objects. Make sure the band object is assigned the material property of vacuum. To set the band object: 1 Select the band object. 2 Right-click Model in the project tree, and then select Motion Setup>Assign Band. The Motion Setup dialog box appears. 3 Click the Type tab. 7-2 Including Motion in the Simulation Getting Started with Maxwell: Transient Problem 4 Specify Rotate as the Motion Type. 5 Click the Mechanical tab. 6 Enter 0.0024 Kg m2 as Moment of Inertia and 0.015 N m sec / rad as the Damping. 7 Click OK. To apply the appropriate mesh operation to the band object: 1 Select the band object. 2 Apply a mesh operation requesting the maximum mesh size of 20 mm for the respective elements. 3 To initialize the problem, right-click Setup1 in the project tree, and select Revert to Initial Mesh. Now you are ready to start the analysis with the effect of large motion included. Including Motion in the Simulation 7-3 Getting Started with Maxwell: Transient Problem Post Process the Transient Results Post processing is performed as for the case without motion. However, more quantities are available to represent as 2D plots (as a function of time) due to the mechanical quantities that are now available. Those quantities can be added as traces when you create the report if you set the solution to Motion. To create a plot of the position as a function of time: 1 Right-click Results in the project tree, and select Create Report. 2 Leave the Report Type set to Transient and the Display Type set to Rectangular Plot. 3 Click OK. The Traces dialog box appears. 4 From the Solution pull-down list, select Motion. 5 From the Category list, select Position. 6 Click the Add Trace button. 7-4 Including Motion in the Simulation 7 Click Done to display the plot. Getting Started with Maxwell: Transient Problem Including Motion in the Simulation 7-5 Getting Started with Maxwell: Transient Problem Follow the same steps to plot the current, torque, and power loss vs. time (selecting a different Category for each plot). The resulting plots are shown below. 7-6 Including Motion in the Simulation Getting Started with Maxwell: Transient Problem Including Motion in the Simulation 7-7 Getting Started with Maxwell: Transient Problem Close the Project and Exit Maxwell Congratulations! You have successfully completed this Maxwell 11 Getting Started guide! You may close the project and exit the Maxwell software. 1 Click File>Save to save the project. 2 Click File>Close. 3 Click File>Exit to exit Maxwell. 7-8 Including Motion in the Simulation 8 Appendix: Understanding the Maxwell Interface In this chapter you will learn how to complete the following tasks: Recognize desktop windows. Use mouse buttons. Set up a matrix. Estimated time to complete this chapter: 15 minutes. Appendix: Understanding the Maxwell Interface 8-1 Getting Started with Maxwell: Transient Problem A.Desktop Windows Project Manager Window Menu Bar Tool Bar History tree Window 3D Modeler Window Message Window Progress Window B.Using Mouse Buttons In general, the left mouse button is used to select items (menu commands, objects, properties, etc.). Double-clicking the left mouse button on an item opens a properties window and allows you to visualize settings and edit properties. Right-clicking is context dependent and, in general, allows you to perform context-specific operations (such as assigning boundary condi- 8-2 Appendix: Understanding the Maxwell Interface Getting Started with Maxwell: Transient Problem tions or excitations, performing field plots on previously selected geometries, or exiting the zoom mode or dram mode, to name a few examples). C.Geometry Φ 102.1 27.8 Φ 209.0 21.4 25.4 Φ 50.8 Φ 107.5 12.7 Axial length (rotor and stator)= 25.4 Coils Appendix: Understanding the Maxwell Interface 8-3 Getting Started with Maxwell: Transient Problem 8-4 Appendix: Understanding the Maxwell Interface

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