The schematic is quite simple: Just an ac source (sinusoidal, 1V, 50Hz)
connected to the ideal transformer's input, and the transformer's output is connected
to a resistor (1k). Transient analysis (0-50ms, 1001 steps). The input voltage is there, but the output is zero.
This is the case for QUCS under SuSE11.1 and under Windoze.
I tested an ac analysis (frequency sweep), and this works fine in all versions.
It seems to be the transient analysis which causes problems.
Actually, I wanted to simulate a simple diode rectifier (half-wave and full-wave),
however, with the same result. To demonstrate QUCS to my students, I work around
with "mutual inductors" (turn ratio = sqrt(L1/L2) and k = 0.99).
Cheers
Thomas
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Could you try our latest qucs development snapshots? does the
transformer work there?
------------------------------------------------------------------------
/[bugs:#83] <http://sourceforge.net/p/qucs/bugs/83/>
http://sourceforge.net/p/qucs/bugs/83/ ideal transformer/
/Status:/ open
/Created:/ Mon Feb 20, 2012 01:30 PM UTC by Thomas Bechteler
/Last Updated:/ Sat Dec 15, 2012 03:09 PM UTC
/Owner:/ nobody
Hi QUCS developer!
The ideal transformers (both under "lumped components") in version
0.0.15 work.
However, they do not work in version 0.0.16!
Thomas
------------------------------------------------------------------------
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Having investigated this, I think there is not a bug after all, and instead there is a misunderstanding of what the ideal transformer component actually does.
The ideal transformer acts as a perfect current transformer, the current in the primary is mutiplied on the secondary. If you just put a voltage source across the terminals, it acts like a short circuit, so there is infinite current. At the same time in this case, there is no resistance, and therefore no voltage drop across the tranformer inputs, hence the output voltage is also zero.
The ideal transformer component does not reflect a real physical transformer device, a real device must have winding resistance and inductance, and only works with AC voltages. An ideal transformer can transform DC current, which is physically impossible in the real world (maybe some exotic superconducting device I'm not aware of).
What changed in Qucs 0.0.15 -> 0.0.16 as far as I can tell was that the behaviour was actually corrected for DC simulation.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
<html>
<head>
<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Good! another bug to close
Hello Thomas,
could you provide more details and an example schematic?
Carsten
Hi Carsten!
The schematic is quite simple: Just an ac source (sinusoidal, 1V, 50Hz)
connected to the ideal transformer's input, and the transformer's output is connected
to a resistor (1k). Transient analysis (0-50ms, 1001 steps). The input voltage is there, but the output is zero.
This is the case for QUCS under SuSE11.1 and under Windoze.
I tested an ac analysis (frequency sweep), and this works fine in all versions.
It seems to be the transient analysis which causes problems.
Actually, I wanted to simulate a simple diode rectifier (half-wave and full-wave),
however, with the same result. To demonstrate QUCS to my students, I work around
with "mutual inductors" (turn ratio = sqrt(L1/L2) and k = 0.99).
Cheers
Thomas
I can confirm, somebody in the qucs-help list had this problem. You can see it with this test circuit, plotting Vout shows a flat line.
<Qucs Schematic 0.0.16><Properties>
<View=0,0,800,800,1,0,0>
<Grid=10,10,1>
<DataSet=2.dat>
<DataDisplay=2.dpl>
<OpenDisplay=1>
<Script=2.m>
<RunScript=0>
<showFrame=0>
<FrameText0=T\x00EDtulo>
<FrameText1=Dibujado por:>
<FrameText2=Fecha:>
<FrameText3=Revisi\x00F3n:>
</Properties>
<Symbol>
</Symbol>
<Components>
<R R1 1 470 270 15 -26 0 1 "50 Ohm" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
<Tr Tr1 1 300 270 -29 38 0 0 "1" 1>
<GND * 1 470 300 0 0 0 0>
<Vac V1 1 140 270 18 -26 0 1 "1 V" 1 "100 Hz" 0 "0" 0 "0" 0>
<.TR TR1 1 150 420 0 65 0 0 "lin" 1 "0" 1 "0.01" 1 "101" 0 "Trapezoidal" 0 "2" 0 "1 ns" 0 "1e-16" 0 "150" 0 "0.001" 0 "1 pA" 0 "1 uV" 0 "26.85" 0 "1e-3" 0 "1e-6" 0 "1" 0 "CroutLU" 0 "no" 0 "yes" 0 "0" 0>
<VProbe Vin 1 220 140 28 -31 0 0>
</Components>
<Wires>
<330 300 470 300 "" 0 0 0 "">
<330 240 470 240 "" 0 0 0 "">
<270 300 270 360 "" 0 0 0 "">
<140 300 140 360 "" 0 0 0 "">
<140 360 230 360 "" 0 0 0 "">
<270 200 270 240 "" 0 0 0 "">
<140 200 140 240 "" 0 0 0 "">
<140 200 210 200 "" 0 0 0 "">
<210 200 270 200 "" 0 0 0 "">
<210 160 210 200 "" 0 0 0 "">
<230 360 270 360 "" 0 0 0 "">
<230 160 230 360 "" 0 0 0 "">
<470 240 470 240 "Vout" 480 200 0 "">
</Wires>
<Diagrams>
</Diagrams>
<Paintings>
</Paintings>
Hi,
I appreciate a lot Qucs for personal works or teatching purposes but...
the question is the same as Thomas :
What's new about ideal transformer ?
The ideal transformer works in version 0.0.15 but not in version 0.0.16 under Windows 7.
I test the supply schematic "supply.sch" given in http://qucs.sourceforge.net/examples.html
Furthermore the symmetrical transformer seems to not work in version 0.0.15 ?
Many thanks !
For those who have an interest with this bug.
Found this "distrib" of Qucs which works perfectly with Windows 7 with ideal (symmetrical or not) transformer :
http://www.mydarc.de/dd6um/QucsStudio/qucsstudio.html
Could you try our latest qucs development snapshots? does the transformer work there?
I will investigate this today.
On 06/06/2013 21:40, Frans wrote:
Related
Bugs:
#83It does seem there's an issue, and possibly related to this commit:
http://sourceforge.net/p/qucs/code/1837/tree//trunk/qucs-core/src/components/trafo.cpp?diff=50cc93d82718464452f00ccf:1836
I'll see if going back to the original code for trafo.cpp solves the
problem.
Great!
On 7-6-2013 10:38, Richard C wrote:
Related
Bugs:
#83Having investigated this, I think there is not a bug after all, and instead there is a misunderstanding of what the ideal transformer component actually does.
The ideal transformer acts as a perfect current transformer, the current in the primary is mutiplied on the secondary. If you just put a voltage source across the terminals, it acts like a short circuit, so there is infinite current. At the same time in this case, there is no resistance, and therefore no voltage drop across the tranformer inputs, hence the output voltage is also zero.
See here for more information:
http://qucs.sourceforge.net/tech/node48.html
The ideal transformer component does not reflect a real physical transformer device, a real device must have winding resistance and inductance, and only works with AC voltages. An ideal transformer can transform DC current, which is physically impossible in the real world (maybe some exotic superconducting device I'm not aware of).
What changed in Qucs 0.0.15 -> 0.0.16 as far as I can tell was that the behaviour was actually corrected for DC simulation.
As in my last post on this bug, there is no bug.
<html>
<head>
<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Good! another bug to close
</body>
</html>
Related
Bugs:
#83