Setting Demagnetization/Magnetization Computations for Source Designs

(2D and 3D Magnetostatic and Transient Solvers)

When a magnetic device with permanent magnets is overloaded, or after a short circuit, irreversible demagnetization may occur due to magnetic field and temperature changes. As a result, the subsequent operating point will no longer lie along the original BH curve, but along the demagnetized recoil line at the worst operating condition.

This process can be modeled in Maxwell using Set Demagnetization/Magnetization Computations. The demagnetization/magnetization process of the magnet is modeled in the source design, and the practical normal application is modeled in the target design.

The linked demagnetization or magnetization designs act as sources (excitations) in the target design. These links are managed as Permanent Magnet Field excitations. Users can setup either object-based or design-based links. The Hc outputs from the source design are mapped to the target design mesh, thus eliminating the restriction of target/source designs employing the same geometries.

Note: This mapping is straightforward for non-hysteresis based models because the Hc output from the source design is a single value plus direction per mesh element. For hysteresis-based models, the Hc output from the source design is a demagnetizing curve per mesh element, and a mapping approach is non-trivial. Thus this process is not applicable when the design has any object modeled with hysteresis materials. Demagnetization/magnetization links for this type of design continues to require the same mesh between target and source designs.

Limitations

A design can only be the target for either magnetization or demagnetization, but not both.
A design can compute either magnetized or demagnetized operating points, but not both.
Object-based and design-based links cannot coexist.
Object-based links are not supported when there is any object assigned with a hysteresis-based material model.

For the magnetization computation, Maxwell provides two possibilities: anisotropic magnetization, and isotropic magnetization.

For anisotropic magnetization, the magnetization direction is determined by the direction specified by the user in the field for the Unit Vector input of Magnetic Coercivity on the panel of View/Edit Material during material setup.

For isotropic magnetization, the magnetization direction is determined by the orientation of the computed magnetizing field from the field solution. In such a case, the user has to set all three components of the Unit Vector input of Magnetic Coercivity to zero (0) on the panel of View/Edit Material window during material setup so that Maxwell knows the direction is computed, rather than specified by user.

General Procedure for Setting Demagnetization/Magnetization Computations for Source Designs

To set demagnetization/magnetization process computations for a source design:

Note: Demagnetization/Magnetization points computation settings specific to the Hysteresis Model-Based Magnetization Approach are described in the Using the Hysteresis Model-Based Magnetization Approach section.

Click Maxwell > Excitations > Set Magnetization Computation to open the Set Demagnetization/Magnetization Computations dialog box. You can also open the dialog box by right-clicking Excitations in the Project Manager, then selecting Set Magnetization Computation on the context menu; or by right-clicking in the Modeler window and selecting Assign Excitation > Set Magnetization Computation.

By default, No operating points computation is selected.
Select either the Compute demagnetized operating points or Compute magnetized operating points radio button. At least one object must be selected to compute data if Compute magnetized operating points is selected.

Note: Multi-select is supported by holding the Ctrl or Shift key while clicking.

Note: An object coordinate system (CS) must be created and assigned to each magnet object in the history tree.
Click OK to accept the settings and close the dialog.

The configured source design can now be linked to if you want to create Permanent Magnet Field Excitations for 2D and 3D Transient and Magnetostatic Solvers.