How to obtain the values of R, L and C of a series RLC model of experimentally obtained frequency domain response data in MATLAB?

I have collected frequency domain response data and wanted to model an RLC series circuit from it. How should I proceed?

Answer 1

[Star Strider]

This is ‘circuit synthesis’ and it is (unfortunately) not trivial.

A series RLC model:

>--- R - L - C --->

Vin Vout

>----------------->

will have one pole at the resonant LC frequency.

You can find that easily enough by calculating the Fourier transform and then specifically plotting only the imaginary part as a function of frequency. The pole will be the frequency midway between the highest and lowest values of that plot. The function zeroes are the other zero-crossings of that plot (and could include zeroes at the origin and infinity, and will affect the order of the system).

Using the System Identification Toolbox can help significantly by determining the parameters that best characterise that transfer function. Begin with the idfrd function and go from there, probably using tfest, then using the compare function to asess the result. Then use that result to compute the component values, choosing the best from what may be a very large number of possible combinations.

That is how I would approach it.

[Sudhee]

Thank you so much for the quick response Star Strider.

.

[Star Strider]

As always, my pleasure!

Answer 2

[Muzaffar]

I need to make a design tf function