Am 08.06.2016 um 02:31 schrieb Mike Monett:
I was not interested in examining the frequency response, saturation
effect or core losses. These are only important after the core goes
into saturation.
I was only interested in the result of switching at the peak or at
the zero crossing. This is clearly defined at the beginning of the
document.
...
The saturation and core losses are outside the scope of the
investigation. The investigation was only to examine the effect of
switching at the peak or at the zero crossing. This was clearly
stated at the beginning of the paper.
My analysis correctly defined an unloaded transformer as the only
case where switching at the peak or the zero crossing made any
difference. This was the goal, and it was met.
Saturation is not outside the scope. It is the very heart of the problem.
You need to build up a voltage opposite to the grid voltage to keep the
current small.
That requires an inductance and that requires a core that can be magnetized.
If the core is already magnetized to the limit from a previous session,
it is as good
as simply not there at all. What remains is some meters of copper wire
without an
appreciable L and that is not enough.
I'm haunted by that effect myself on a regular base in that I have a fat
class A Krell
audio amplifier and it pops the fuse of my living room once in about 5
times of
switching it on.
I also showed that very few solid state switches were available that
switched at the peak, that most vendors simply supply devices that
switch at the zero crossing and state to get a model that will
accept the surge currents, that switching at the peak could cause
severe surge currents with capacitive loads,
Nobody uses large transformers anymore, everybody has a diode bridge ,
capacitor
and a DC/DC behind it. Then zero voltage switching makes sense.
and that I could not
find any reference that stated switching at the peak would not cause
core saturation.
I provided references that zero voltage switching leads to saturation,
and so did others.
Your comments offer no additional information regarding the
advisability of switching at the peak or the zero crossing. The
information you do supply is irrelevant to the problem, and mostly
irrelevant to LTspice.
you are right. This is not a LTspice problem but your modelling problem.
> Attila Kinali
It is upon moral qualities that a society is ultimately founded.
All the prosperity and technological sophistication in the world
is of no use without that foundation.
You need to consider getting new sigs. The two you post have little
or nothing to do with timenuts, and I'm sure everyone has them
memorized by now.
OMG , I'm not Attila, but I may need a special time nuts .sig!
regards, Gerhard
--
Es ist schon alles gesagt worden, aber noch nicht von jedem. (Valentin)
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