Power Stealing Transformer Core Design

[elgersmad]

Hello,

You guys will really like this.  The first simple experiment consists of winding two halves of a toroid in opposite directions, or sending current opposite directions through two separated windings on opposite halves of the core.  If you look at the core, one winding puts north right next to north from the second winding, and south facing south electromagnetically.  What happens is that since like poles repel, the magnetic lines are ejected from the core and you can detect those with another magnet or compass.

Lenz's Law & Faraday's Law

When ever you induce a current in a transformer core, shorting the secondary produces an opposing magnetic field.  So, if you wind two windings on two halves of a toroidal core, make one the primary and the other the secondary, when the secondary is shorted it produces back EMF and an opposing magnetic field.  Just like the DC model produces magnetic lines that escape the core, at that junction, it happens with the AC voltages applied and the secondary shorted.

That means that this top view of four U core halves, or two toroids, with one cut in half would produce a second path for a magnetic circuit at a 90 degree angle, which would give all of those magnetic lines a place to go when you take power from the secondary.  The more power you take from the secondary, the more power these two Thief Coils produce that would have normally been a loss.  The more you take from the secondary, the more the Thief Coils Generate.

[elgersmad]

The only thing that might make that more efficient is a small gap between the Thief Coils, and the native C core halves.  If there is a slot cut and the length is from the primary to the secondary on both halves of the primary secondary magnetic circuit, it can really help it.  Second, the two Thief Coil Gaps should only be a 1 to a several millimeters if that.  You need to keep the Thief Coils close, but not too close.  When the primary kicks in, you don't want the Thief Core Sections involved in the magnetic circuit.  Only when Lenz's Law and Faraday's Law are playing out to produce Opposing EMF do you want the Thief Coils to produce a magnetic circuit.  So, gapping is important to make work right.  From the primary to the secondary, core material should direct and flush meet.

[importfanatik]

Could you explain your diagram a little more?
Seems like you effectively have 3 secondaries, one of which is shorted.
What stops the magnetic field from the primary from traveling through all 3 secondaries?
And whats stopping the lenz induced EMF from all 3 secondaries from reaching the primary?

[elgersmad]

Look, I've studied magnetics for years.  I gave you the simplest experiment I could think of, for you to do yourself so you could see a toroid will or won't attract to a piece of metal based upon exciting the coils.  If it's north south north south working clockwise, then it doesn't attract to anything.  Working clockwise if it's North South on one half, and South North working clockwise on the other half, it will attract to a piece metal.  No power does not mean that there are no magnetic lines in the core.   Lenz's Law and Faraday's Law tell you where the magnetic lines will come from.  Go to the Wiki link I gave you, read the article.

I updated the my drawing to include the Reluctance gaps and the slot mentioned and left of the drawing.

In test, here are the results you should see. 

Primary Power ON
Secondary Open
Thief Coils No Voltage.

Test circuit, Three Light Bulbs and one switch.

Place a light bulb across the windings of the secondary of the Thief Coil, then place a switch and light bulb on the secondary.  Apply power to the primary of the transformer.

When you turn on the light bulb on the secondary,  The Light Bulbs on the Thief Coils will light up.  Those two cores cannot and will not pick up magnetic lines from the two core halves that meet flush with the slot between them until the secondary has power drawn from it and faraday's law and lenz's law come into play producing counter EMF.  The counter EMF will escape the core where the slot is shown.  North will connect to South through the gapped cores.  But, if the Top View is all you have and it's North, the Bottom view is the same except the magnetic lines being ejected from there are the South Pole's magnetic lines.

These are U Cores.
U Cores  It takes four of the U shaped pieces to assemble this.  They come in all sizes.  Less than half inch and less than a buck a pop.

[elgersmad]

The basic experiment really consists of apply a DC voltage to a common mode choke.

The Common Mode Choke Winding

If you want to see how the magnetic field lines would escape the core, then this dynamo magnet will show you how opposing electromagnetic fields escape the core.  Both solenoid windings on either side of the rotor have north up and south down, and the iron bar which has been shaped to fit around the rotor carries the opposing poles which are pushed out of the core and over the gap where the rotor is located.
Bipolar Field Generator

Lenz's Law and Faraday's Law, are proof that when you use power on the secondary, you have created or produced that event seen in the DC coils of the dynamo.  The gap, keeps the generator coils/Thief Coils out of the magnetic circuit that consists of the Primary and Secondary windings in my drawing.  But, when those magnetic lines oppose in the core, they will eject where the two U cores meet flush even though they seem to have the best magnetic circuit.  When they are forced out of the core, the two Thief Coils are waiting for Faraday's Law and Lenz's Law to place those ejected magnetic lines there.