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Re: [Help-gnucap] howto use different phase and frequency in sources for

From: Rubén Gómez Antolí
Subject: Re: [Help-gnucap] howto use different phase and frequency in sources for transient analysis?
Date: Tue, 27 Oct 2009 23:00:04 +0100
User-agent: Mozilla-Thunderbird (X11/20090701)

Hello al:

al davis escribió:
Quick answer .. I will get back with more details in a few days.

Ok, We wait for these details.

What is the Pspice syntax for specifying phase on a "sin" source? It's not in Berkeley spice.

There is the usual custom for propietary apps: deform the standard to complicate the competence (like HTML's IE tags, for example):

Here are the 90% of my problems: exercises thought for Pspice with incompatible syntax for free engines like Gnucap or Ngspice; or model, macromodel for Pspice (like thyristor, UJT...) with a difficult -or imposible for a newbie, like me- way to translate to Berkeley spice.

It would be just another way to specify the delay ... the phase at time = 0.

I just did find a bug in the way the Fourier command computes relative phase.

But that is not the problem you saw.


The absolute phase you see in a Fourier analysis is referenced to the start of the interval, so it will be different on different runs depending on the starting time. It does appear to be correct, from that perspective.

That really doesn't matter.  It is just a time shift.

I think the reason your waveform built from the sum of sources doesn't match the signal you took the Fourier transform of is that you are only using up to the fifth harmonic, so there is a lot missing.

Perhaps I should explain a bit more:

Start with a Diode brigde rectifier and do a Fourier analysis:

# i(LS)     --------- actual ---------  -------- relative --------
#freq       value        dB      phase  value        dB      phase
 0.         0.0063273  -43.98   90.000  405.58E-6  -67.84  100.271
 60.        15.601      23.86  -10.271  1.           0.00   -0.000
 120.       0.011073   -39.11  -92.415  709.79E-6  -62.98  -82.144
 180.       11.821      21.45  148.226  0.75772     -2.41  158.497
 240.       0.0071613  -42.90   85.933  459.04E-6  -66.76   96.205
 300.       6.3621      16.07  -57.484  0.40781     -7.79  -47.213
 360.       0.0028582  -50.88  -93.075  183.21E-6  -74.74  -82.804
 420.       2.009        6.06   77.596  0.12877    -17.80   87.867
 480.       189.74E-6  -74.44 -162.004  12.162E-6  -98.30 -151.732
 540.       0.94716     -0.47  143.495  0.060713   -24.33  153.766

and transient analysis for view i(VS).

Next exercise: check grafically source current i(VS) how sum of fundamental and two first harmonics (3 and 5).

I obtain the three currents well, something "displaced" compare with Pspice output.

But i(VS) is not the wave expected.

Also, the circuit doesn't look correct, but that could be due to partial cut and paste errors.

There are no errors in paste circuit, I'm sure now that circuit is not correct; this is my fault: I should work on it a bit more.

Thanks so much for your fast answer.


Salud y Revolución.

Libertad es poder elegir en cualquier momento. Ahora yo elijo GNU/Linux,
para no atar mis manos con las cadenas del soft propietario.
Desde El Ejido, en Almería, usuario registrado Linux #294013

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