Electromagnet power transfer question.

[nwman]

Thanks for taking a moment to read this thread. I'm just looking to increase my knowledge of how electromagnetism works. I'm not trying to prove any idea in this thread but to get help understanding how a certain electromagnet configuration would perform in a certain configuration. I'm going to try and keep this as simple as possible. I do consider myself a novice in this field so please forgive my ignorance. Ok, on with the idea.

Below is simple graphic of the configuration of the electromagnets. There are two A and B. The electromagnets' core is made of grain oriented laminated steel. The polarity alignment of the two are opposing (N to S).

There are two connecting bars (C and D) that have induction coils wrapped around them. These are made of the same Material as the cores and have small air gaps between them.

So, please point out any misconception I have about how this would work. Say both electromagnets (EM) are off (A and B). Now lets say you started to energize (pulse) A and B at opposite times thus making an alternating current relative to the C and D coils.

-At this point would you receive two separate and opposite wave length AC currents from coils C and D?
-Would there be back EMF in the system or would it continue to function normally?
-Is there a way to combine the two separate / opposite AC currents into one AC current without great loss?
-The main question I had, if it would operate as I imagine, is what would be a "conservative estimate" of the amount of ?loss? from the power put into A and B to the amount of power that could be collected at C and D? Would it be 10% 20% 50% etc....
- Any other comments or questions?

Thanks for your help.

Tim

[TinselKoala]

It's an interesting question. Some points come to mind:
First, there isn't any way to estimate the efficiency based on the description, because so much depends on the materials and the exact geometry.
Second, whatever the efficiency, those air gaps will decrease it. I don't understand why you think they are needed.
Third, as soon as you begin pulsing one or both the coils A and B, the coils C and D will begin responding with a sinusoidal voltage swing, i.e. AC.  Just hook the coils in series if you want to "combine" them.
Fourth, there is BEMF whenever you "turn off" an electromagnet coupled to a coil.
Fifth, there will most likely be a resonant frequency of pulsation of the A and B coils that will give the maximum power transfer or even an actual resonant voltage rise in the "secondary" formed by the C and D coils.

By the way, what you have described is pretty darn close to being a transformer, but they usually take pains to omit the air gaps in transformer design.

[Honk]

Winding a coil around a permanent magnet will give you no output what so ever, simply
because you cannot affect the "hard" magnetism of a permanent magnet by a surrounding coil.
This is the difference between "soft magnetics" vs "hard magnetics".
http://www.arnoldmagnetics.com/products/index.htm

[gyulasun]

@Honk

Dear Honk,  would you mind reading Tim's description on his setup again,  there is no permanent magnets involved but all the cores are made from laminations. The poles indicated in the picture are from the electromagnets in one moment I think.

@Tim

I tend to agree with TinselKoala's opinions  [except his Third statement: the waveform of the output coils will be also pulse-like shapes like at the  input, sinusoidal waveforms can only come out when you tune the output (or the input) coils into resonance with the pulse frequency].
So basically your setup seems a normal transformer. When you switch on one of the EM's coils say A (the other coil, B is off as you mean), flux can flow through the closed magnetic path (assuming small air gaps): this corresponds to  the situation of a normal AC transformer primary coil excited with AC and the half periode of this AC wave sends flux through the core in one direction. 
Next, you switch off  A and switch on B with polarity as you showed, this corresponds to the normal transformer's primary coil excited with the other half periode of its AC waveform that sends the flux through the core in the other direction.

Do you mean on back EMF the pulse that is created when you switch off the current in any inductive coil?  If so, I prefer calling it flyback pulse, and of course those flyback pulses appear across your EM coils whenever you switch their current off.

rgds,  Gyula

[Honk]

Opps, sorry. I've never encountered a drawing on a regular transformer device using dedicated N/S polarization.
In all cases there has always been pemanent magnets inserted and the N/S show direction. Like the MEG.