Isotropic hysteretic Preisach models for magnetic materials in Standard User mode


Since Flux 2019, the user can represent the hysteretic behavior of isotropic magnetic materials with a vector Preisach-type model in Transient Magnetic applications, both in 2D and in 3D projects. However, this feature was available only in Beta mode (Flux supervisor options to set to access it).

Several performance and stability issues linked to the Preisach B(H) material properties have been corrected since then. For a complete list of issues, the reader is referred to the Fixed Defects section of this release note, for instance to the FX-15670 and FX-16241 paragraphs.

Consequently, this feature has been promoted to Standard mode in Flux 2022 and is now considered fully supported and qualified. This transition into Standard mode also signifies that the compatibility of Flux projects containing this feature is guaranteed from now on.

Please remark that the names of the Preisach B(H) material properties changed slightly. For the sake of clarity, they are now called in Flux 2022 as follows:

  • Isotropic hysteretic, Preisach model described by 4 parameters of a typical cycle and
  • Isotropic hysteretic, Preisach model identified by N triplets.

Furthermore, a new documentation chapter providing an overview of the Preisach-type model implemented in Flux and guidelines on how to create a material with this kind of B(H) magnetic property is now available in the user guide.

The following improvements related to the Preisach B(H) material properties were also included in Flux 2022:

  • Two Altair Compose model identification tools are now provided in Flux to help users create a material characterized by the two Preisach B(H) properties above from a set of magnetic measurements. For further details, the user is referred to the new Material identification chapter of the Flux user guide.
  • A new type of predefined sensor for evaluating the magnetic power on a computation support is now available. This sensor is useful for separating magnetic power and Joule losses while post-processing in Flux projects containing regions described by hysteretic materials.
  • A new quantity dPowMagV representing the magnetic power density has also been defined in Flux. The corresponding button dPowerMag/dV has been added to the formula editor as well. These can be used to post-process the magnetic power density on a computation support as an isovalue color map, for instance.

Example of application

A material characterized by an isotropic, hysteretic Preisach-type B(H) property may be used to solve the well-known benchmark problem TEAM 32. The device corresponding to this problem is the double-fed magnetic circuit represented in the figure below.

図 1. Schematic 2D representation of the double-fed magnetic circuit of the TEAM 32 problem considered in this Flux 3D example.

With the help of the appropriate Preisach identification tool provided in Flux, it may be shown that the material used in the TEAM 32 device corresponds to the following triplets (ai , bi , ci) for a data fitting with N = 2:

表 1. Triplets for the Preisach material of the TEAM 32 problem for a centered, symmetric (B,H) cycle with a saturation magnetic flux density of 1.3 T at 10 Hz.
i ai (T) bi (A/m) ci (A/m)
1 0.5043 11.08 59.37
2 0.4162 130.19 114.39

The data from the table above may be used to create a material with a B(H) property of the type Isotropic hysteretic, Preisach model identified by N triplets. Once the material is created, it may also be assigned to a Magnetic non-conducting volume region in a Flux 3D project.

After solving of a parametric scenario controlled by time in a Transient Magnetic application, the hysteretic behavior of material may be verified with the help of sensors while in post-processing. The following results show the establishment of a rotating magnetic field at the position C1 of the magnetic circuit and the hysteretic relationship between the magnetic flux density B and the magnetic field intensity H at the centermost position of the magnetic circuit.

図 2. The rotating magnetic flux density during a cycle at position C1 (a) and the hysteresis loop at the centermost position of the magnetic circuit (b). Part (b) also shows the (B,H) measurements used for the identification of the input triplets (ai,bi,ci).

For the complete version of this example of application, please refer to the new chapter Hysteretic Isotropic Material characterized by a Preisach-type model in Flux of the user guide.