How to model "LITZ" or "STRANDED" coils and windings?

[jewlersarty]

In Simulation of transformer and electrical motors in software like ansys maxwell we usually have to model conductors, but does it matter how to draw them?

I use Ansys software for finite element simulations. Maxwell, Simplorer, RMXpert and other toolboxes. but I always have a doubt on how to model a coil?! should we use a single geometry as a whole coil or we should draw wires one by one! but even if we could, what should we do about twisted litz wires? it is almost impossible to model them in real shape.

What consideration should have in modeling?

Thanks!

 

[jewlersarty]

No response to this?

 

[rjenkinsgb]

Litz vs. solid only applies if the skin depth of the conductor becomes relevant at the working frequency.

If whatever package has parameters for the conductor type, shape and resistance of the wire being simulated, then you should be able to adjust things there.

Transformer design is not a field I have particularly been involved in though.

 

[Dick Cappels]

I suspect one reason you might not be getting much of a response is that most of us are not familiar with those software packages.

Secondarily, Litz has an advantage over solid in that eddy current losses are much lower in Litz, especially when magnetic cores are involved.

 

[crutschow]

If the transformer frequency is such that skin depth is a factor then you could model the wire resistance based upon that, either for Litz or single conductor wire.

 

[crutschow]

Litz has an advantage over solid in that eddy current losses are much lower in Litz, especially when magnetic cores are involved.

I know Litz wire reduces the skin-effect wire resistance, but I don't see how it would affect eddy current losses in a magnetic core(?).

 

[Dick Cappels]

In the case of a wire close to a ferrite core the gradient of magnetic flux is great, and when this varies, it induced currents in the wires perpendicular to the core.

I heard about this in a talk at the Society For Information Display Conference in San Francisco in about 1982 by a fellow from Tektronix. After the talk I went back to my lab and re-wound some transformers that were getting too hot (@64 kHz) with multiple insulated wire instead of solid enameled wire and the temperature dropped dramatically.

Think about why iron core laminations are so thin.

 

[crutschow]

I went back to my lab and re-wound some transformers that were getting too hot (@64 kHz) with multiple insulated wire instead of solid enameled wire and the temperature dropped dramatically.

But I think that was from the lowered skin-effect wire resistance, not anything to do with a change in the magnetic eddy currents.

Think about why iron core laminations are so thin.

Again, that's to reduce the eddy current losses in the magnetic material, which has nothing to do with whether the wire is single strand or Litz.
You are confusing apples and oranges.