Re: gEDA-user: Mathematical expressions in gnucap?

[Peter Clifton <pcjc2@xxxxxxxxx>]

> There is nothing as easy as the "B" device.  Options available 
> are 1. define as a poly, 2. use a table, 3. code a bm_ plugin 
> in C++ (This really is easy.  Tell me what you want and I will 
> show you.) 4. A more elaborate behavioral model as a .model 
> file, which becomes a plug-in.

The model is to simulate EMF induced in a generator given arbitrary
mechanical input.

I'm defining the mechanical position input to be a voltage across two
terminals (say 1m / V), which I will differentiate to get velocity (say
1m/s / V). (Or I could feed it both velocity and position, rather than
worrying about how to differentiate within my model).

There are some parameters I'll want to pass defining the generator
geometry (winding pitch etc..), but basically I get some "K" dependant
on position, which when multiplied by input velocity gives induced EMF.

(K comes from the flux integrated over a generator coil, and is
basically a sinusoidal function).

Future refinements of the model would include computing mechanical force
as a function of current drawn from the output terminals, but right now
being able to simulate the EMF would be very useful.

I'm planning to build a generator model with this idealised EMF,
followed by an equivalent circuit to consider the "parasitics" such as
resistance, phase inductance and mutual coupling between each phase.

I started digging this afternoon, and thought the VCVS model might be a
useful point to start from. I then got side-tracked wondering if I
should be using the .model compiler, and whether I had to make up a
letter to prefix my new device with.

I appreciate your help. If you want to point me at any documentation to
RTFM on building models, please do so..

Regards,

Peter C.




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