chapter 1 introduction. training manual electromagnetic analysis in workbench march 4, 2005...
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Chapter 1
Introduction
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Training Manual
Electromagnetic Analysis in Workbench
A. Feature Overview• Workbench EMAG features at release 9.0:
1) 3D modeling ONLY, using the SOLID117 edge formulated element available in ANSYS.
2) An enclosure tool is available to conveniently model the domain surrounding the electromagnetic device/system.
3) Automatic gap detection refines mesh locally in air gaps.
4) Can model nonlinear permeable materials with BH curves, permanent magnets, and coils.
5) A winding tool facilitates the modeling of multiple windings in rotating machinery.
6) Can calculate field quantities (flux density, field intensity), force and torque, inductance, and flux linkage.
7) At release 9.0, only magnetostatic analyses are possible.
8) Parameters used to define dimensions, material properties, etc. may be varied automatically in a series of solutions using the parameter manager.
EnclosureField from a periodic arrangement of coils from the winding editor
Gap detection
BH data
Armature forces Parameter Manager
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Training Manual
Electromagnetic Analysis in Workbench
B. Underlying Technology
• The 3D SOLID117 used in Workbench correctly calculates the discontinuity in the tangential component of B at iron-air interface
–Edge formulated element has 12 edge-flux DOF’s (AZ) at each midside node
–In SOLID117, AZ IS NOT the z component of the magnetic vector potential. Rather, it is the integral of the tangential component of A along an element edge. A useful physical interpretation: the sum of AZ around a closed loop formed by edges equals the flux passing through the loop (right hand rule).
–AZ units: Webers (volt-seconds)
–You may not remove midside nodes – they are used to support the edge-flux DOF AZ
–The presence of midside nodes does not imply a quadratic shape function. SOLID117 shape functions are linear.
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Training Manual
Electromagnetic Analysis in Workbench
C. Enclosures
• Use the Enclosure Tool to define surrounding electromagnetic domain (“air”). Predefined shapes include Box, Sphere, and Cylinder. The “Cushion” is how far the enclosure extends beyond the surfaces of the modeled geometry. Merge Parts? should be set to “Yes” when solid model geometry is present.
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Training Manual
Electromagnetic Analysis in Workbench
D. Boundary Conditions
• Surfaces may either be flux normal (naturally occurring) or flux parallel.
• Specify flux parallel on even symmetry boundaries and to approximate far field by applying to external surfaces of enclosures under Environment in the Simulation Tree.
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Training Manual
Electromagnetic Analysis in Workbench
E. Modeling Permanent Magnets• PM polarity may be in X direction in a user defined coordinate system (named “PM_CSYS”
in this example). The coordinate system orientation may be modified.
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Training Manual
Electromagnetic Analysis in Workbench
F. Modeling Permanent Magnets• PM properties may be defined as “linear hard” (shown here) with coercive force Hc and
residual induction Br
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Training Manual
Electromagnetic Analysis in Workbench
G. Modeling Conductors
• Option 1: Create a solid conductor* from a solid body
• Procedure:
A. “Insert” a conductor on the environment branch of the tree using imported or created solid geometry.
B. Define the number of turns.
C. “Insert” a voltage condition on one face
D. “Insert” an impressed current on the opposite face.
Voltage = 0 on this face
* In general, the current density in a solid conductor is NOT uniform over its cross section. With this conductor option, if symmetry is used in the model, only the portion of the conductor present in the modeled portion of the system should be included. The current distribution is that of a solid with DC excitation (no skin effects, no induced voltage or current in the conductor). The distribution of current may be visualized using this option.
Current injected into this face
Resulting current distribution
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Training Manual
Electromagnetic Analysis in Workbench
…Modeling Conductors
• Option 2: Create a stranded conductor* from a line body
• Procedure:
A. Create a sketch
B. Promote the sketch to a line body
C. Promote the line body to a winding body
1: sketch
2: line body
3: winding body
4: field created by winding body in spherical enclosure
* The current density in a stranded conductor is always uniform over its cross section. All conductors present in the physical system must be included in the model, even if symmetry is used.
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Training Manual
Electromagnetic Analysis in Workbench
…Modeling Conductors
• Option 3: Create a series of stranded conductors* (for rotating machines) using the winding editor
• Procedure:
A. Bring up the winding editor tool.
B. Define the number of slots.
C. Edit the values of the table to define coils in each phase, connectivity, number of turns, and geometry.
3 4 5
6
Slot 1
Slot 2
Slot 3
Slot 4
Slot 5
Slot 6
1
2* The current density in a stranded conductor is always uniform over its cross section. All conductors present in the physical system must be included in the model, even if symmetry is used.