femmt 0.5.4

FEM Magnetics Toolbox

FEM Magnetics Toolbox (FEMMT)

This README only provides a short overview. For more information please have a look at the detailed documentation here <https://upb-lea.github.io/FEM_Magnetics_Toolbox/intro.html>__.

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:
    * 2D axi-symmetric cylindrical simplification
    * `Inductor </femmt/examples/basic_inductor.py>`__, `2-winding transformer </femmt/examples/basic_transformer.py>`__, `n-winding transformer </femmt/examples/basic_transformer_6_windings.py>`__
    * Arbitrary (distributed) air gap positioning in center leg
    * Variety of winding interleaving schemes
    * Special geometries:
        * `Center tapped transformer </femmt/examples/basic_transformer_center_tapped.py>`__
        * `Magnetic shunt </femmt/examples/basic_transformer_integrated.py>`__ (transformer with integrated inductor)
        * `Stacked core </femmt/examples/basic_transformer_stacked.py>`__ (transformer with integrated inductor)
    * Round litz wire, implemented according to `Niyomsatian et al.: Frequency-domain homogenization for litz-wire bundles in finite element calculations <https://ieeexplore.ieee.org/document/9007233>`__
    * Round and rectangular solid wires
    * Different winding schemes (hexagonal, left/right, top/down, ...)
    * Parallel connection of solid wires
    * Insulation distances (winding2core, winding2winding)
    * Many `examples </femmt/examples/>`__ to learn and understand FEMMT
    * Databases
         * Litz wire database
         * Core geometry database
         * Conductor materials: temperature curves
         * Ferrit materials: permeability / permittivity `material database <https://github.com/upb-lea/materialdatabase>`__ (datasheets and own measurements)

* Solver features:
    * Implemented using `ONELAB <https://onelab.info/>`__
    * Current excitation
    * Frequency domain solver
    * Litz wire loss model for proximity and skin effect (`Niyomsatian et al.: Frequency-domain homogenization for impedance characterization of litz-wire transformers in 2-D finite element models <https://ieeexplore.ieee.org/document/7695378>`__)
    * Core loss calculation for real materials (data from material database)
        * Amplitude dependent loss angle (Local resolution of complex permeability)
        * Equivalent permittivity data for eddy current calculations
        * Effect of dimensional resonance is considered
    * Thermal solver
        * Thermal conduction (Poisson equation)
        * Fixed temperature and isolation boundary conditions
        * Verified model for potted core

* 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
• Optimization:
  • Advanced optimization algorithms by connecting to optuna <https://github.com/optuna/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 <https://upb-lea.github.io/FEM_Magnetics_Toolbox/intro.html>__. You will find tutorials and a function description.

Literature

• An Open-Source FEM Magnetics Toolbox for Power Electronic Magnetic Components <https://ieeexplore.ieee.org/document/9862128>__

• An Open-Source FEM Magnetic Toolbox for Calculating Electric and Thermal Behavior of Power Electronic Magnetic Components <https://ieeexplore.ieee.org/document/9907554>__

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 <https://upb-lea.github.io/FEM_Magnetics_Toolbox/intro.html>`__.

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 </femmt/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 <Contributing.rst>`__.

Changelog
------------

Find the changelog `here <CHANGELOG.md>`__.

License
----------

`GPLv3 <https://choosealicense.com/licenses/gpl-3.0/>`__

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.

.. |geometry_translated| image:: docs/images/geometry_translated.png
.. |FEMMT_Screenshot| image:: docs/images/FEMMT_Screenshot.png
.. |femmt_gui_definition| image:: docs/images/femmt_gui_definition.png
.. |counting_arrow_system| image:: docs/images/counting_arrow_system.png


# Changelog
All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).


## [Unreleased]
## [0.5.4] - 2024-07-01
### Fixed
- Require materialdatabase 0.3.0 for full materials compatibility 

## [0.5.3] - 2024-05-23
### Added 
- Conductor placing strategies

## [0.5.2] - 2024-04-30
### Added 
- log_material.json output for material logging information 
### Fixed
- Improved non-linear solver, as there were some one-shot results without any iteration
- Wrong displayed currents when using excitation_sweep() with complex currents
- Fixed incomplete python package in version 0.5.1

## [0.5.1] - 2024-02-06
### Fixed
- Fix documentation issues
- Fix material database dependency issues

## [0.5.0] - 2024-02-06
### Added
- various integration tests, unit tests for materialdatabase
- three winding transformer
- center-tapped transformer drawing schemes
- stacked transformer
- parallel connection of solid turns

### Changed
- API has lots of changes. Check out the examples and the documentation.

### Updated
- materialdatabase: material loading and interpolation of operation point

## [0.4.0] - 2022-12-19
### Added
- updated and improved syntax
- cost functions for core and wire material according to IEEE paper 'Component cost models for multi-objective optimizations of switched-mode power converters'
- connect femmt to the new pip package for the material database
- add optimization routine for automated design process
- Update GUI according to material database connection and optimization routine


## [0.3.0] - 2022-09-01
### Added
- Add color dictionaries for individual geometry visualization
- Added output json file for thermal simulation
- Add Parser to read and visualize the result.json-files
- Add first version of reluctance model including an example file
- Added dynamic mesh density algorithm for the winding window
- Simulation settings are now stored in the log file. A simulation can be started using given log-file.
- Added a new interface for femmt

### Fixed
- fix #13: improve reading the onelab filepath 
- fix #16: Wrong Mesh is simulated when changing the number of turns
- fix #17: Error with integrated_transformer mesh
- fix #19: Scale update in result plots
- fix #22: Fix bug for air-gap positions 0 and 100 percent

## [0.2.1] - 2022-04-28
### Updated
- possibility to assign fixed magnetic loss angle and conductivity in update_core function 
- new isolation scheme (looking from core to all windings): core_cond_isolation=[top, bottom, inner, outer] instead of core_cond_isolation=[prim2core, sec2core]
- gmsh 4.9.5 as minimum requirement

### Added
- example for foil winding inductor
- conductor material can be chosen from a small material database, used in update_conductors(), e.g. conductivity_sigma=["copper"]
- isolations for thermal simulation

### Fixed
- fix #15: Secondary to Core isolation thickness not working

## [0.2.0] - 2022-02-14
### Updated
- updated the winding generation
- updated the femm reference model
- updated project structure
- updated meshing to hybrid mesh
- updated class structure
### Added
- add file Analytical_Core_Data.py
- add example files DAB_Input_Data.py, DAB_trafo_optimization.py
- add file mu_imag.pro
- add folder femmt/thermal
- add result_log_electro_magnetic
- add horizontal interleaved winding scheme
- add method write_log() to femmt.py
- add thermal simulation with onelab
- add femm heat flow validation with femm
### Fixed
- fix #5: changed typo to L_h_conc = self.M**2 / self.L_22
- fix #11: rename femmt.py to femmt_classes.py due to package problems

## [0.1.2] - 2021-08-08
### Updated
- updated strand approximation
### Added
- add option for dedicated stray path
- add complex permeability and permittivity for core materials for Core Loss estimation
- add iGSE and GSE for Core Loss estimation

## [0.1.1] - 2021-08-11
### Updated
- updated inductance calculations
- code clean up

### Fixed
- fix #2: config.json was not read correct
- fix #3: Install pyfemm on Windows machines in case of not installed pyfemm

## [0.1.0] - 2021-07-28
### Added
#### Structure
- add README.md
- add CHANGELOG.md
- add femmt/__init__.py

#### Essentials
- add femmt/FEMMT.py
- add femmt/functions.py
- add femmt/ind_axi_python_controlled.pro
- add femmt/solver.pro
- add femmt/BH.pro

#### Examples
- add femmt/FEMMT_geometric.py
- add femmt/basic_example.py

#### Additional/Experimental Code
- add femmt/pandas_json.py
- add femmt/femm_test.py
- add femmt/SimComparison.py
- add femmt/SolidComp.py
- add femmt/CompRes.py

[Unreleased]: https://github.com/upb-lea/transistordatabase/compare/0.5.4...HEAD
[0.5.4]: https://github.com/upb-lea/transistordatabase/compare/0.5.4...0.5.3
[0.5.3]: https://github.com/upb-lea/transistordatabase/compare/0.5.3...0.5.2
[0.5.2]: https://github.com/upb-lea/transistordatabase/compare/0.5.2...0.5.1
[0.5.1]: https://github.com/upb-lea/transistordatabase/compare/0.5.1...0.5.0
[0.5.0]: https://github.com/upb-lea/transistordatabase/compare/0.5.0...0.4.0
[0.4.0]: https://github.com/upb-lea/transistordatabase/compare/0.4.0...0.3.0
[0.3.0]: https://github.com/upb-lea/transistordatabase/compare/0.3.0...0.2.1
[0.2.1]: https://github.com/upb-lea/transistordatabase/compare/0.2.0...0.2.1
[0.2.0]: https://github.com/upb-lea/transistordatabase/compare/0.1.2...0.2.0
[0.1.2]: https://github.com/upb-lea/transistordatabase/compare/0.1.1...0.1.2
[0.1.1]: https://github.com/upb-lea/transistordatabase/compare/0.1.0...0.1.1
[0.1.0]: https://github.com/upb-lea/transistordatabase/compare/0.1.0...0.1.0