Electronics > Projects, Designs, and Technical Stuff
Transformer proximity effect: Pri and Sec interaction? (aka Interleaving?)
jmelson:
--- Quote from: cur8xgo on June 11, 2019, 09:19:21 pm ---Why can't you just wind them simultaneously the whole way (or until one winding has all its turns)?
--- End quote ---
This would make the BEST transformer, in terms of coupling between windings. BUT, on the other hand, it would be worst for interwinding capacitance.
Also, hard to maintain isolation between windings where that may be required (line voltage vs. low voltage). This would be called a bifilar (or trifilar, etc.) winding, and there are places where it is used. But, the interwinding capacitance can be a real issue.
Jon
cur8xgo:
This is my idea of how the proximity effect eddy current flows...but I know something is wrong here.
This is a view I don't see in the texts. Showing the winding as a spiral with the top of the core removed.
Does the eddy current take this long circuitous path around the entire conductor length? If not..why would it "cross" at any particular point?
Also this doesn't explain why the current density gets distorted...
EDIT: Yes this shows current going two opposite directions inside a conductor. So what I think ends up happening here is..the eddy "current" superimposes on the other current in the wire and thats what distorts the current density. However I don't see how the magnitude of the eddy current is near the same as the main current. And does the eddy "current" (or effect) increase stepwise each layer?
T3sl4co1l:
--- Quote from: cur8xgo on June 12, 2019, 08:02:01 pm ----i in C1 creates an mmf INSIDE of it, which is not shown on the diagram.
-i in C2 creates an mmf (and therefore flux) which IS shown on the diagram, between C1 and C2. This mmf should be twice the mmf that C1 generated. Therefore C1 is experiencing "two mmf".
-The mmf C1 experiences, according to the right hand rule, should generate a current that is flowing out of the page, in the same direction as the winding current.
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The concentric circle and dot are showing current out of the page, and the crossed circle, into.
The winding direction (curling to the right or left) doesn't matter, if there are conductors to the right of these which are carrying the load current i.
If there are no other conductors and this is a lone inductor, then the right side is where the currents are piling up, so the right side is towards the center of the core.
Tim
T3sl4co1l:
Corrected diagram:
The trick is, we can only add up currents in the cross section, as long as the cross section is a true representation of the circuit. Sooner or later the turns need to actually get into the cross section, though, and that is where we must break away from the 2D model and consider the 3D fields. Namely, the eddy currents wrap around the affected conductor, where the outer conductor enters.
I also drew eddies on the "start" lead just because. :)
Ed: oh, the 2nd layer turnaround arrows should be a single one. That doesn't add up as shown.
Tim
cur8xgo:
--- Quote from: T3sl4co1l on June 12, 2019, 10:11:16 pm ---Corrected diagram:
The trick is, we can only add up currents in the cross section, as long as the cross section is a true representation of the circuit. Sooner or later the turns need to actually get into the cross section, though, and that is where we must break away from the 2D model and consider the 3D fields. Namely, the eddy currents wrap around the affected conductor, where the outer conductor enters.
I also drew eddies on the "start" lead just because. :)
Ed: oh, the 2nd layer turnaround arrows should be a single one. That doesn't add up as shown.
Tim
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Thanks! That took some work and I appreciate it. I'm going to go through a day or two of study and see if I can get to the next stage of understanding, your drawing will be very useful.
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