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modeling trafo

M

Michael Robinson

Jan 1, 1970
0
I'm trying to find the quickest way to account for saturation of a
transformer in LTSpice.

The reason I need to include saturation in the model is because it's a
blocking oscillator.

There's a nonlinear transformer model in the library at the yahoo group (the
Chen model), but it includes a couple of parameters related to the
hysteresis loop.

I don't know what I would use for the hysteresis parameters and would like
not to have to use those extra parameters, if at all possible. No B-H loop,
just a transformer that can saturate, but has no hysteresis.

There's an "arbitrary inductor" model that takes saturation into account
while ignoring hysteresis. If I could use this model in a transformer by
simply coupling two inductors it would make my life easy, because I have the
volt-seconds figure for the trafo I intend to use.

This wiki shows the inductor model:

http://ltwiki.org/index.php5?title=The_Arbitrary_Inductor_model

So I tried putting two arbitrary inductors in my schematic and coupling
them. LTSpice tells me I can't use coupling with arbitrary inductors. Same
result when I try to couple an arbitrary inductor with an ideal inductor.

So I'm still at square one. Do I have to use the Chen model, or is there an
easier way to do this?
 
J

John KD5YI

Jan 1, 1970
0
I'm trying to find the quickest way to account for saturation of a
transformer in LTSpice.

The reason I need to include saturation in the model is because it's a
blocking oscillator.

There's a nonlinear transformer model in the library at the yahoo group (the
Chen model), but it includes a couple of parameters related to the
hysteresis loop.

I don't know what I would use for the hysteresis parameters and would like
not to have to use those extra parameters, if at all possible. No B-H loop,
just a transformer that can saturate, but has no hysteresis.

There's an "arbitrary inductor" model that takes saturation into account
while ignoring hysteresis. If I could use this model in a transformer by
simply coupling two inductors it would make my life easy, because I have the
volt-seconds figure for the trafo I intend to use.

This wiki shows the inductor model:

http://ltwiki.org/index.php5?title=The_Arbitrary_Inductor_model

So I tried putting two arbitrary inductors in my schematic and coupling
them. LTSpice tells me I can't use coupling with arbitrary inductors. Same
result when I try to couple an arbitrary inductor with an ideal inductor.

So I'm still at square one. Do I have to use the Chen model, or is there an
easier way to do this?

Look in folder LTC\LTspiceIV\examples\Educational for
NonLinearTransformer.asc

See if that will help you.

Cheers,
John
 
M

Michael Robinson

Jan 1, 1970
0
John KD5YI said:
Look in folder LTC\LTspiceIV\examples\Educational for
NonLinearTransformer.asc

See if that will help you.

Cheers,
John
That's good. It says you can model a transformer that saturates by shorting
the input of an ideal
transformer with an inductor that saturates.
 
J

John KD5YI

Jan 1, 1970
0
That's good. It says you can model a transformer that saturates by shorting
the input of an ideal
transformer with an inductor that saturates.

I ran the model and looked at the current into the magnetic device. It
looks like a classical saturating magnetic device.

Am I missing something?
 
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