Re: gEDA-user: Symbol/Model Parameters (values?)

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Sun, 2008-05-18 at 23:59 -0700, David Griffith wrote:
> On Sun, 18 May 2008, Mark Lorenz wrote:
> 
> > First, Werner, thanks for helping me get a working diode model in place.
> > The link you provided was also quite helpful.
> >
> > Now I'm struggling with transformers, I understand that ngSpice doesn't
> > support them natively, buy geda-symbols did come with a transformer symbol.
> > So the question is, how do I tell what values this model takes, and what
> > order then go get entered into gschem?  This information would be really
> > helpful for any model that one isn't familiar with.
> 
> Ugh!  I'm trying to learn how to use spice and now I learn this about
> transformers.  Anyone have any suggestions for designing high voltage
> power supplies?

Spice can do coupled inductors, or you can use a construct with voltage
sources / current sources to model an ideal transformer. You could add
an inductor to model magnetising reactance, and a parallel resistor to
represent core losses.

However:

If you want to model non-linear effects such as saturation / magnetic
hysteresis, then you will need to implement a sub-circuit which
implements the behaviours of the core. Take a look at search results for
"Jiles Atherton spice". A colleague of mine has implemented this in
P-Spice for modelling of HF lighting ballasts, but I don't know of any
ngspice / spice 3 compatible implementation.

Kind regards,

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)



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