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Use an external signal in time domain into the frequency domain

Posted Aug 4, 2019, 5:06 a.m. EDT Electromagnetics, Low-Frequency Electromagnetics Version 5.4 3 Replies

Antonio Sunseri
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Hi, I want to use an external wave (in file .txt) in frequency domain electric circuit. Using time domain I have no problems and I have used this waveform in DC generator, but the problem is to use this waveform in frequency domain. I have realized the waveform using root.t so in frequency domain the software doesn't know the variable t. Is there anyone with the same problem? Thanks to all

3 Replies Last Post Aug 5, 2019, 10:03 a.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 5 years ago Aug 4, 2019, 3:04 p.m. EDT
Updated: 5 years ago Aug 4, 2019, 2:58 p.m. EDT

Antonio,

there is indeed no time in frequency domain so you cannot use a waveform to excite the model. The frequency domain solver only solves for pure harmonic excitations which are defined by a frequency and a complex amplitude. If your waveform is harmonic then just apply its frequency and amplitude, if it is something different you will need to use time domain.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Antonio, there is indeed no time in frequency domain so you cannot use a waveform to excite the model. The frequency domain solver only solves for pure harmonic excitations which are defined by a frequency and a complex amplitude. If your waveform is harmonic then just apply its frequency and amplitude, if it is something different you will need to use time domain. Cheers Edgar
Antonio Sunseri
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Posted: 5 years ago Aug 5, 2019, 4:41 a.m. EDT
Updated: 5 years ago Aug 5, 2019, 4:39 a.m. EDT

Thanks for the reply, I asked to make sure it couldn't be done. I have another question, with the previous txt file I made the waveform and I made it periodic in the analytic node, after I added it as a local variable. The moment I place it in a DC generator of the circuit I get a completely different waveform in the generator, I have attached the two waves. What are the steps to follow to avoid this problem? I want to realize the second image but I get the first one.

Thanks for the reply, I asked to make sure it couldn't be done. I have another question, with the previous txt file I made the waveform and I made it periodic in the analytic node, after I added it as a local variable. The moment I place it in a DC generator of the circuit I get a completely different waveform in the generator, I have attached the two waves. What are the steps to follow to avoid this problem? I want to realize the second image but I get the first one.
Antonio Sunseri
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Posted: 5 years ago Aug 5, 2019, 10:03 a.m. EDT
Updated: 5 years ago Aug 5, 2019, 9:56 a.m. EDT

I think I found the problem, the step time used in transient solution was too big, so I was missing many frequency components during the study

I think I found the problem, the step time used in transient solution was too big, so I was missing many frequency components during the study

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