Nonlinear magnet (HcB, HcJ, Br module)

An improved way to define a nonlinear magnet model that aligns better with the available parameters found in the manufacturers' data sheets.

Introduction

From Flux 2024.1 an improved nonlinear magnet model (defined by HcB, HcJ and Br module) is available and replaces the previous nonlinear magnet model defined by Hc and Br module. The next two sections detail what it is modified compared to the previous model (Improvements ) and what is the expected Flux behavior with materials created before 2024.1 version (Backward compatibility).

Improvements

Due to the improved nonlinear magnet model, the Flux dialog box is upgraded accordingly as well as the picture displaying the material characteristics and the mathematical formula in the User Guide.

  1. The dialog box is adapted to the improved nonlinear magnet model:

    • Maximal relative permeability (µr,max) field is replaced by Intrinsic coercivity (HcJ) field and Normal coercivity symbol Hc is clarified to HcB
      Remarque : HcJ value can not directly replace µr,max value, a conversion is required (Backward compatibility)

    • The Remanent flux density (Br) and the Transversal relative permeability (µr┴) remain the same.

    • In addition, the option to take into account demagnetization during the solving process can be used with the improved model.



  2. B(H) and J(H) curves are as in manufacturers data sheets and the inputs for defining the nonlinear magnet model are easier distinguished (HcB, HcJ and Br).


  3. The mathematical formula is reformulated in this way:

    The results obtained with both approaches, namely with the formula used in the Nonlinear magnet described by Hc and Br module and this one, are the same.

  4. Moreover, in the Material Identifier available from the Flux Supervisor, the tool Nonlinear magnet described by Hc and Br module has been upgraded to comply with the latest Flux modifications: its graphical interface has evolved to have the new parameters, the python command provided as output has been updated to the new Flux model and the tool has been renamed as Nonlinear magnet described by HcB, HcJ and Br module. As a reminder, this tool "transforms" measurements from real experiments to the values needed for defining the nonlinear magnet model in Flux projects.

Backward compatibility

Materials defined with Hc and Br module (created with a Flux version lower than 2024.1) will be updated or not to the new improved model (HcB, HcJ and Br module), when opened with a newer Flux version, based on the following rules:

  • If at least one of the fields of the material has a parameter, the material will remain in read-only mode, and it is not possible to be automatically updated. The result is the same if the previous python command is used (Hc and Br module) and one of the inputs for the definition of the model includes a parameter.
  • If no parameters have been used for the definition of the material, there are two possibilities:
    • The project is solved: The material will be automatically updated to the improved model when the user will delete all the results of all the existing solved scenarios.
    • The project is unsolved (for all the existing scenarios): Automatically the material will be updated with the improved nonlinear magnet described by HcB, HcJ and Br module. The python command (with Hc and Br module) could also be used but the created material will be automatically transformed to the improved model (HcB, HcJ and Br module).