Ecm with diffusion

[MehrdadBabazadeh]

Description

The existing Equivalent Circuit Model (ECM) has been extended to create a more accurate model named the ECMD (ECM+Diffusion). This improvement involved adding a "diffusion_element" to the circuit alongside updates to the voltage_model and other relevant files. The key difference lies in how terminal voltage is calculated. The original ECM relied on average State of Charge (SoC). With the diffusion option enabled, the ECMD utilizes a newly calculated Surface SoC, providing a more precise representation. Additionally, a new term, eta_diffusion, is introduced. This term represents the voltage drop caused by diffusion limitations and is placed in series with the existing Open Circuit Voltage (OCV) within the circuit. This approach isolates the pure effect of diffusion on the voltage calculations. Finally, a Python script named Compare_ECM_ECMD.py is included as an example to demonstrate the comparison between the original ECM and the new ECMD.

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit) (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[valentinsulzer]

Thanks! Is there any reference for this in the literature?

[MehrdadBabazadeh]

Thanks! Is there any reference for this in the literature?

Hi. The used references are in the following. We have validated the results with an implementation of Chebyshev Collocation method developed by separate Python code:

1. Fan, Chuanxin, et al. "Data-driven identification of lithium-ion batteries: A nonlinear equivalent circuit model with diffusion dynamics." Applied Energy 321 (2022): 119336.
2. Binous, Housam, Abdullah A. Shaikh, and Ahmed Bellagi. "Chebyshev orthogonal collocation technique to solve transport phenomena problems with matlab® and mathematica." Computer Applications in Engineering Education 23.3 (2015): 422-431.

The address for the developed Python code, used to validate SoC profile is:
https://github.com/MehrdadBabazadeh/Chebyshev-Collocation.git

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.46%. Comparing base (109b9c4) to head (fde2343).
Report is 159 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4254      +/-   ##
===========================================
- Coverage    99.50%   99.46%   -0.05%     
===========================================
  Files          288      289       +1     
  Lines        22079    22146      +67     
===========================================
+ Hits         21970    22027      +57     
- Misses         109      119      +10     

☔ View full report in Codecov by Sentry.
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[valentinsulzer]

@MehrdadBabazadeh thanks for sharing the references, can you document these as described here? https://github.com/pybamm-team/PyBaMM/blob/develop/CONTRIBUTING.md#citations

Also, you can link that git repository in the docstring of your submodel. These references will be useful in future if someone wants to know more about the model

[kratman]

One last thing now that #4266 was created to address set_events being misnamed.

Changes were made

[kratman]

Seems OK now as long as the tests pass

[kratman]

@MehrdadBabazadeh Are you still working on the coverage for this?

[MehrdadBabazadeh]

Yes. Ferran and me will go on the remaining issues and continue the work next week.

[brosaplanella]

The coverage issues seem to be unrelated to this PR, so that should be good to go. Waiting to merge as I don't know if we need to wait for #4311

[arjxn-py]

I don't know if we need to wait for #4311

@brosaplanella, we can merge this one without waiting for #4311. Coverage failure seems unrelated to me too as giving failure in pybamm/util.py which is failing for old changes

[brosaplanella]

@all-contributors please add @MehrdadBabazadeh for code and tests

[allcontributors]

@brosaplanella

I've put up a pull request to add @MehrdadBabazadeh! 🎉

[MehrdadBabazadeh]

Thanks to @brosaplanella and other team members!