Hello,
I've google/google groups'ed a bit but anyhow I cannot make an *ideal* transformer to work. The file
-- ideal transformator
.control ac dec 20 1k 1g plot vdb(3) .endc
.subckt transformer 1 2 3 4 vsense 1 2 dc 0 e1 1 2 3 4 1 f1 3 4 vsense -1 .ends
v1 1 0 dc 0 ac 1 r1 1 2 10 X1 2 0 3 0 transformer r2 3 0 1k
.end
-- makes Macspice hang... Please note that for my purpose I cannot use \'K\' coupled inductors. DC behaviour of the ideal transformer is of no interest. Cheers, Michael
On Mar 23, 10:41 am, Michael Zedler wrote: ...
...
OK, let's look just at the transformer. You have a short circuit (a DC voltage source set to zero volts) across nodes 1 and 2. And you have a dependent voltage source e1 which is also across those terminals. It is not a good idea to put two voltage sources in parallel. I would suggest you try putting them in series. Does that help? Then you can have a primary (1-2) voltage controlled by what the secondary voltage is, while still using vsense to sense the current in the primary.
Cheers, Tom
"Michael Zedler" schrieb im Newsbeitrag news:eu13g9$886$ snipped-for-privacy@news.lrz-muenchen.de...
Hello Michael,
It looks similar to the ideal transformer from this article.
I have made a subcircuit from this example:
Plese change the voltage ratio "10" to the desired value. For a 1: transformer replace the 10 by 1 and the -10 by -1.
Best regards, Helmut
PS: If you have some kind of Windows emulator, you could try LTspice. It also runs with WINE in Linux. LTspice has a state of the art graphical interface for schematics and waveforms.
A full blown version of the ideal trafo with parameter passing for LTspice
How a netlist for a TRAFO-instance could look in LTspice:
XU1 10 0 50 0 TRAFO N=1
Normally one would use a symbol in the schematic of course.
Symbol file, name it trafo.asy
Version 4 SymbolType BLOCK RECTANGLE Normal 80 64 -48 -80 TEXT -22 -48 Left 0 TRAFO WINDOW 39 17 24 Center 0 SYMATTR Prefix X SYMATTR SpiceModel TRAFO SYMATTR Description Ideal Transformer SYMATTR SpiceLine N=1 PIN -48 -64 NONE 8 PINATTR PinName 1 PINATTR SpiceOrder 1 PIN -48 48 NONE 8 PINATTR PinName 2 PINATTR SpiceOrder 2 PIN 80 -64 NONE 8 PINATTR PinName 3 PINATTR SpiceOrder 3 PIN 80 48 NONE 8 PINATTR PinName 4 PINATTR SpiceOrder 4
How very strange, i am used to making ideal and real transformers with an Lm term coupling "normal" inductors. Almost sure to be a better simulation of any possible real circuit.
-- JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller
Helmut Sennewald schrieb:
Works like a charm, thank you!
Michael
joseph2k schrieb:
In most cases your statement may be correct, but not for this one: Joint simulation of some lumped elements together with a distributed microwave circuit (the latter represented by a canonical Foster equivalent circuit which requires ideal transformers).
Michael
OK. What is going on with the Foster equivalent circuit that normal Lm ideal transfromers will not work.
-- JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller
An ideal transformer is needed; no parasitic inductance, coupling of 1. Again, this is an *equivalent* circuit. It models the distributed circuit. And if non-ideal transformers were used essentially the transfer function of the destributed (physical) (multiport-)circuit were altered.
Michael
OK, i do not understand "parasitic inductance" in this context. I have a little experience (near trivial) with "transmission line transformers" in PWB and MMIC arenas. Please elucidate.
-- JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller
In the meantime i did some googling on Foster equivalent circuit. Wow, was i ever on the wrong track. Not only was my suggention of using standard Lm terms waste lots of simulation time to no good; it would actually completely destroy the integrity of the simulation. I have to admit though that the basic idea is wonderful, it makes analysis of something wierd like a fractal antenna doable.
-- JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller
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