Demagnetization improvements

Improvements related to magnets and their demagnetization in Transient magnetic projects


Flux can evaluate the demagnetization of magnets during the resolution of a transient magnetic scenario since its version 2019.1 (in 2D and 3D). This feature is available through the creation of materials with a B(H) magnetic property of type Nonlinear magnet described by Hc and Br Module, which contains the material option Taking into account demagnetization during the solving process.

In the new version 2022.3, Flux brings several improvements related to magnets and the evaluation of their demagnetization. These improvements are detailed in the following sections.

New vector quantity representing the remanent magnetic flux density of demagnetized magnets

The post-processing of the remanent magnetic flux density of magnets described by a material allowing the consideration of demagnetization effects during the resolution has evolved in Flux 2022.3.

Previously, the user had access to the remanent magnetic flux density of a magnet modified by demagnetization effects through the scalar spatial quantity BrDemag. The corresponding BrDemag button was accessible from the formula editor.

In Flux 2022.3, a new vector quantity BrMagnet is available. This quantity has the advantage of containing the explicit direction and orientation of the remanent field. The quantity BrDemag may still be used, but the corresponding button is no longer visible in the formula editor. A BrMagnet button has also been added to the formula editor.

Please remark that the related vector quantity Br remains available and still represents the magnetization state of a magnet accordingly with its material definition and its region orientation before any demagnetization effect.

A comparison of quantities Br and BrMagnet is available in Figure 1 and Figure 2 below:

Figure 1. The vector quantity Br representing the original magnetization state of the magnets in the rotor of an electrical machine.

Figure 2. The vector quantity BrMagnet representing the magnetization state of the magnets in the rotor of an electrical machine at a given time step, after consideration of demagnetization effects.

New tools for displaying demagnetization results on magnets

In Flux 2022.3, the visualization shortcuts available for displaying the magnetization state of magnets were improved to account for the new vector quantity BrMagnet presented in the previous section.

While in pre-processing, the user can display the Br vector quantity representing the magnetization state of magnets before the consideration of demagnetization effects. This may be accomplished by selecting Display arrows on magnets: material Br in the menu Physics.

After resolution of a transient scenario, additional display actions become available in the Graphic menu through the Graphics on magnets option, namely:
  • Display arrows on magnets: material Br: displays arrows representing the Br vector quantity on all magnets, as in pre-processing.
  • Display arrows on magnets: Br at the current step: displays arrows representing the BrMagnet vector quantity on all magnets.
  • Display isovalues on magnets: Br at the current step: displays isovalues representing the module of vector quantity BrMagnet on all magnets.
Figure 3 contains two screen captures showing these shortcuts in Flux GUI.
Figure 3. Screen captures showing the improved menu shortcuts for displaying Br and BrMagnet in pre-processing (a) and post-processing (b).

Extended support for 2D-axisymmetric transient magnetic applications

In Flux 2022.3, it is now possible to use magnets with the option for demagnetization during resolution in Transient Magnetic 2D applications with axisymmetric domains. Previously, this feature was only available in Transient Magnetic 2D-plane and 3D applications.