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FEM Magnetics Toolbox (FEMMT)

This README only provides a short overview. For more information please have a look at the detailed documentation here.

Python toolbox to generate preconfigured figures for FEM simulation tools in power electronics.

The toolbox is accessible via python code or a graphical user interface (GUI), which current development status is experimental.

All core shapes are simulated as 2D symmetric cores, as shown in the figure.

geometry_translated

Overview features

Stable features

  • Component features:
  • Solver features:
  • Pre/Post processing:
    • Linear eddy current analysis via input current based FFT
    • Pre-visualization of ferrite material (measurement) data interpolation
    • Field visualization in gmsh GUI (magnetic flux density, eddy current losses, ...)
    • Inductance matrix for n-winding transformer
    • Transformer equivalent diagrams for 2- and 3-winding transformer
  • Optimization:
    • Parallel computing to speed up simulations (no cpu core limitation)
    • Examples for Pareto optimization to adapt to your own optimization problem

Experimental features (under development)

  • Component features:
    • Reluctance module is currently working for a single optimization example and not fully implemented yet.
  • Solver features:
    • Time domain solver is experimental
  • Optimization:
    • Advanced optimization algorithms by connecting to optuna
  • GUI:
    • Experimental in general

Planned features (Roadmap for 202x)

  • Solver features:
    • Core loss calculation from non-sinusoidal flux
    • Local temperature dependency (currently only lumped temperature assignment, e.g. general temperature for all windings)

Not supported features

  • Not supported component features:
    • Toroidal core
  • Not supported solver features:
    • Voltage excitation

Documentation

Please have a look at the documentation. You will find tutorials and a function description.

Literature

Installation

To run FEMMT python (version 3.10 or above) and onelab is needed.

ONELAB installation

  • Go to https://onelab.info/
  • Download the Desktop Version for your OS (Windows, Linux or macOS)
  • Unpack the software and remember the file path. This will be needed later when installing FEMMT.

Further steps for macOS(ARM)

  • Go to https://onelab.info/
  • Download the Desktop Version for Windows
  • Copy the "conveks.py" and "Onelab.py" files and paste them into the "onelab" folder
  • Go to http://getdp.info/
  • Download the macOS(ARM) Version
  • Open the downloaded folder, navigate to "bin" and copy the "getdp" application file
  • Paste the copied file into your "onelab" folder

Install FEMMT

FEMMT can be installed using the python pip package manager. This is the stable release version (recommended).

pip install femmt

For working with the latest version, refer to the documentation.

Minimal example

This toolbox is able to build a complete FEM simulation from simple Python code. The following figure shows the Python code on the left and the corresponding FEM simulation on the right. FEMMT_Screenshot

To run a minimal example please have a look at the examples.

GUI (Experimental)

There is a first preview for a GUI. Installing this is a bit cumbersome at first, but will be simplified in the future:

  • Download the complete repository via Code -> Download ZIP and unpack it.
  • Or clone the repository
  • Install the development version of femmt using pip install -e .
  • Run python .../path-to_femmt/femmt/gui/femmt_gui.py

Please note, the GUI is experimental.

femmt_gui_definition

Troubleshooting

If the working directory is within OneDrive, there are problems writing .dat files, which are basic for FEMMT. The following error messages appear:

The system cannot find the file specified: your_directory/femmt/electro_magnetic/Strands_Coefficients/coeff/pB_RS_la0.6_4layer.dat
FileNotFoundError: [Errno 2] No such file or directory: your_directory/results/values/j2F_1.dat

The solution is to place the working directory of FEMMT including the Python virtual environment outside the OneDrive folder.

Bug Reports

Please use the issues report button within github to report bugs.

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change. For contributing, please refer to this section.

Changelog

Find the changelog here.

License

GPLv3

History and project status

This project was initially written in matlab using FEMM simulation tool. It became clear that the project was no longer a small project. The project should be completely rewritten, because many new complex levels have been added. To place the project in the open source world, the programming language python is used.