NI Multisim custom transformer

[vasko]

I need ferrit (not iron) transformer in my virtual circuit. It has primary 4+4 turns of 2mm wire, and secondary 500 turns of 0.3mm wire. Core is ferrit 7x7mm.

I've try transformers that are already in Multisim 11 but they are no good.


Here is random code of transformer in Multisim.

.SUBCKT ts_misc_25_to_1 1 2 3 4 5 
*  *1, 2-- primary winding,  *3,4-- secondary terminal, 5-- neutural
Rs1 1 11 1.000e-3
Rl2 31 3 1.000e-3
Rl3 41 4 1.000e-3
L1  11 2 5.000e+000
L2  31 5 8.001e-003
L3  5 41 8.001e-003
K12  L1 L2 9.999e-001
K13  L1 L3 9.999e-001
K23  L2 L3 9.999e-001
.ENDS

Any help how to code that custom transformer?

[vasko]

No one uses Multisim here?

[Z transform]

In order to simulate a non-linear transformer you need a non-linear inductor across the primary and then you hook secondaries to the primary with voltage controlled current sources. There is an example of such a model that comes with the LTspice (from Linear Technology) spice download (free). A Non-linear transformer like this is one of their example circuits. I have played with it enough to know that it works, but don't have any more experience than that. Their non-linear inductor is based upon the "Chan model" (see below) and you should read a copy of this paper to know how to use it. I can't legally circulate the paper because of copyright issues.

Hope this helps.

Tom
Nonlinear transformer model for circuit simulation

Chan, J.H.; Vladimirescu, A.; Gao, X.-C.; Liebmann, P.; Valainis, J.;
Computer-Aided Design of Integrated Circuits and Systems, IEEE Transactions on
Volume: 10 Issue: 4 Date: Apr 1991
Digital Object Identifier : 10.1109/43.7563

[Z transform]

What i forgot to make clear is: If Multisim has a non-linear inductor then you can build the transformer as they did in the LT spice example which I suggested you look at. How you set up the non-linear inductor to match your core/winding is the tricky part. The LT spice used a non-linear model described in the Chan paper and Multisim may also, but there are several methods for doing this and no standard.

Tom