How to get the equivalent circuit model for the follow impedance spectrum ?

Greetings,

I have this impedance data (freq., real, and imaginary) and I tried to fit these data to multiple models but with no sucess.

Anyone could help with this ?

magnitude spectrum

phase spectrum imaginary values

[Mohamed Ahmed]

thank you very much for your reply.

regarding the data here is another file but with smoother dataset, can it help finding a good fit ?

Answer 1

[akshatsood]

Hi Mohamed,

I understand that you want to derive an equivalent circuit model for the given impedance spectrum. From my understanding, you can try out the following workarounds to fit the data to an equivalent model.

Non Linear Data Fitting: https://in.mathworks.com/help/optim/ug/nonlinear-data-fitting-example.html

The reference attached above discusses usage of two methods namely lsqcurvefit and fminunc to fit a nonlinear function to the provided data. The documentation for lsqcurvefit is attached below for your reference

https://in.mathworks.com/help/optim/ug/lsqcurvefit.html?s_tid=doc_ta

Curve Fitting via Optimization: https://in.mathworks.com/help/matlab/math/example-curve-fitting-via-optimization.html

Further, the following tools on File Exchange might be helpful

https://in.mathworks.com/matlabcentral/fileexchange/69811-zfitgui?s_tid=srchtitle_support_results_2_ZFit

https://in.mathworks.com/matlabcentral/fileexchange/19460-zfit

In case you struggle to narrow down to an approach to fit the impedance data, it would be highly convenient if you could share your code so that I can go through it and address your issue in a more efficient manner.

I hope this helps.