Flux e-Machine Toolbox: About


Starting from the 2019.1 version, Flux has a new tool called Flux e-Machine Toolbox. This coupling is available in 2D, 3D and Skew for the magnetic transient application.

The aim of Flux e-Machine Toolbox is to characterize the behavior of the machine in the "Torque-Speed" area and allows to postprocess various quantities in this area.

Input parameters like the maximum phase voltage RMS , the maximum phase current RMS and the desired Maximum speed of the machine are considered.

Four types of command modes are available:
  • MTPA: Maximum Torque Per Ampere with the standard solving workflow
  • MTPV: Maximum Torque Per Volt with the standard solving workflow
  • MTPA Fast: Maximum Torque Per Ampere with the fast solving workflow
  • MTPV Fast: Maximum Torque Per Volt with the fast solving workflow

Type of machine

In these first versions, only one machine is taken into account by Flux e-Machine Toolbox. It is the Synchronous machine, permanent magnet in three phases (Inner rotor or outer rotor).

Since FeMT 2021, designs where the section represented in Flux contains multiple magnetic poles are supported. You can represent all types of machines, and in particular the fractional slot winding machines which have different periodicities in the stator winding and in the rotor.

In Flux, when generating the coupling component, there is a new field: Repetition number of the stator periodicity (if different of rotor)

In FeMT, in the Settings zone, two new information are displayed:
  • Number of represented pair of poles
  • Repetition number of stator periodicity

Note: For FeMT versions prior to 2021, there was a limitation: only one magnetic pole section had to be represented. All the information had to be contained in one pole pitch.

Type of circuit connection

WYE and DELTA winding connections are supported.

  • On Flux side

    When generating the component, the associated circuit is automatically analysed to know if it's a DELTA or a WYE connection.

  • On FeMt side

    When opening the coupling component in Altair Flux e-Machine Toolbox, the winding connection is displayed in the settings table, in the Circuit section.

About losses

Different losses are computed and postprocessed:

  • Stator Winding Joule Losses: on each coil conductor
  • Rotor Eddy Current Losses: on solid conductor regions (magnet, fret, can,…)
  • Iron losses:
    • In 2D and 3D and in Skew since FeMT 2021:
      • Only computed on non-conducting laminated magnetic regions
      • In Flux, it is advised to choose a material with losses, assigned to these regions (the user has the choice to use LS or Bertotti model)
      • If losses are not defined on the material, default Bertotti coefficients are automatically applied

        (K1=151.88 ; K2=0.07 ; K3=1.19 ; A1=2 ; A2=2 ; A3=1.5)

      Note: For FeMT versions prior to 2021, for Skew projects:
      • Only computed on non-conducting magnetic regions , because the laminated regions did not exist in Skew
      • Default Bertotti coefficients were automatically applied after the Flux solving process

        (K1=151.88 ; K2=0.07 ; K3=1.19 ; A1=2 ; A2=2 ; A3=1.5)

      Note: About FeMT Skew coupling components generated from Flux version 2020.1 or older:

      FeMT 2021 no longer supports computation of iron losses for older Skew projects with no laminated regions.

      However, the old Skew projects can be opened in FeMT 2021 and results of previous simulations computed with older FeMT version can be displayed. But, it is not possible to start a new simulation on this old project.

      In order to run a new simulation on this old project, you will have to open your Skew project with Flux 2021 and regenerate a FeMT coupling component.

Iron losses computation strategy

From version 2024, with the MTPA and MTPV command modes only, the iron losses are computed using a new internal method called "Half cycle". This method allows to compute the iron losses over half an angular period, thus reduces the total number of computation steps and therefore improves performance by reducing computation time without altering the results.

Note: This "Half cycle" method is not available for the MTPA Fast and MTPV Fast command modes.


Here is the process of the Flux e-Machine Toolbox coupling:

Step Software Description
1 Flux Preparation of the Flux project:
  • standard description: geometry, mesh and physics
  • specific description: losses, number of poles, circuit information...
Note: A classic workflow is to use FluxMotor to pre-design the electrical machine and export it in a python srcipt. Then the python script is run in Flux to obtain a Flux 2D project ready to generate the coupling component
2 Flux Generation of the Flux e-Machine Toolbox coupling component
Note: In the options of the generation of the coupling component, it is possible to choose to go directly at the Step 5. After the generation of the coupling component, Flux e-Machine Toolbox is launched (equal to step 3) and the generated component is directly opened (equal to step 4)
3 Flux Supervisor Opening of Flux e-Machine Toolbox starting from Flux
4 e-Machine Toolbox Opening of the Flux e-Machine Toolbox coupling component generated by Flux
5 e-Machine Toolbox Choice of input parameters
6 e-Machine Toolbox Launching of the simulation
  • Either directly in FeMT: the solving process of Flux is launched in batch mode
  • Or through PBS: exporting the required files for PBS, running the computation through PBS and importing the results from PBS

Once the solving process is done, a postprocessing script is run to build the performance mapping

7 e-Machine Toolbox Postprocessing of results