Re: modelling digital control of PWM circuits

On Tuesday 01 March 2011, John Vodden wrote:
> I am trying to find out if gnucap's mixed-mode capabilities
> are suitable for my purposes. Basically, I am trying to
> model digital control of PWM inverter/rectifier circuits
> using ideal switches. I understand that gnucap models
> switches as "time-dependant linear devices" and adjusts the
> simulation timing accordingly.

Should be.  If not, how about helping to add the capability?

> Is it possible to write an external model that can set when
> the switches will operate?  Ideally, this model would be
> triggered at regular intervals (rather like a timed
> interrupt)  and perform calculations based on current or
> voltage measurements to determine the instant at which the
> switches should change state and somehow schedule the change
> of state to take place (perhaps adjusting the control
> voltage of a voltage dependant switch?)

Yes, but how about a switch and a timed voltage source?  Both of 
these are available now.

> I have read about the model compiler in the stable version of
> gnucap but I get the impression that this is somewhat
> obsolete? I also think that the development version is more
> sophisticated than the stable release but I am struggling to
> find documentation. I would greatly appreciate it if someone
> could point me in the right direction of where to start with
> this, or alternatively send me on my way if this is not
> something that gnucap is able to do.

Documentation for the development version is a wiki ..
http://gnucap.org/dokuwiki/doku.php?id=gnucap:manual

Technical documentation is at:
http://gnucap.org/dokuwiki/doku.php?id=gnucap:manual:tech


What is obsolete is the source language.  Modelgen was done long 
ago, before Verilog-A.  

It needs to accept Verilog-A as the source language.  There are 
several possible approaches.  One possible approach is to change 
modelgen to accept Verilog-A syntax.  Other thoughts are to base 
a replacement on ADMS, Icarus Verilog, or System-C.  There have 
been starts on all of these, but since nobody is getting paid, 
none of these were finished.