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

[Rubén Gómez Antolí]

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):

http://www.uta.edu/ee/hw/pspice/pspice08.htm

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.

Ok.

> 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.

Regards.

Salud y Revolución.

Lobo.
--
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
http://www.counter.li.org