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FFT analysis through powergui block is showing empty in signal options.

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Commented: Anwesha Mukjopadhyay on 11 Sep 2020 at 20:34
Hi all,
I have to obtain the fft bar plot of the 5 level stepped sinusoidal wave which is the output of the 5 level cascaded multilevel inverter. I have changed the scope settings also to loggin>struct with time. I have tried changing the powergui to discrete as well with different time steps. Still i am not able to view anything in the FFT bar plot. Can anyone suggest any remedy for it or is there any setting problem in my MATLAB. I'm using MATLAB 2019 version.


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Answers (1)

Kaashyap Pappu
Kaashyap Pappu on 26 Jul 2019
Given that I have been unable to reproduce this issue, a possible workaround I have identified would be to connect the output of the “PS-Simulink Converter” to the “Scope”, check “Log Data to workspace” under the Logging tab and select “Save format” as an Array.
Run the model, and the logged data would appear as an array with 2 columns. Using the “fft” function and “bar” function, calculate the Fourier transform on the second column of the logged variable and obtain the bar plot. If the variable name is ScopedData, the second column can be accessed using ScopedData(:,2).
Use the “abs” function to obtain the magnitude of FFT. Note that "fft" returns a 2-sided spectrum.
The documentation for “fft” is here, for “abs” is here and for “bar” is here.
Hope this helps.


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