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Author Topic: Critical pulse motor core info  (Read 11144 times)

aether22

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Critical pulse motor core info
« on: March 08, 2008, 03:04:27 AM »
Whoa!

Ok, THIS IS BIG

I just woke up and still had eddy currents on my mind from the night before and I realized that for open path magnetic systems EVERY SINGLE METHOD EVERY USED TO DIVIDE THE CORE IS USELESS OR NEARLY SO! (there are few conventional devices that have open magnetic paths)

The ONLY way to do it is to have a cut ring, or a coil with or without breaks in it. (but obviously not shorted and must be insulated as it is more vulnerable than normal laminates)

This impacts every Adams motor ever made, EVER, this impacts Thanes generator, this impacts the majority of OU electromagnetic designs.

This has either been hurting the efficiency of, or possibly even a hidden ingredient of every open circuit electromagnetic device.

Let me explain, with open paths the flux leaks out so the further you get away from the source the field is less strong and so is the induction from it if time varying.
And so currents induced in strongly induced locations will short through poorly induced locations.

The amazing thing is that if you think about it, it matters not one iota if you cut the core up length wise, think about it, current will still flow just fine. (yes, it would be odd looking but it will still flow pretty much the same, the fact that the currents must pass each other in a long thin wire (or a laminate strip) means nothing!)

« Last Edit: March 09, 2008, 02:57:11 AM by aether22 »

aether22

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Re: Critical pulse motor core info
« Reply #1 on: March 09, 2008, 02:59:21 AM »
With almost 200 reads of this in the New section and almost 40 here and only one off topic reply, figure I might need to encourage reply.

Do you understand how this invalidates almost all methods for avoiding eddy currents in open magnetic circuit cores?

Do you Agree or disagree or are you unsure?

Do you agree that is is a reasonably important discovery since it effects most every magnetic Free Energy magnetic device and hence the word needs to get out? (very few employ a closed magnetic circuit)

Or do somehow think that it is of little importance somehow?

Any reply would be appreciated.

I wrote what I was thinking and feeling at the time, maybe the shouting and such put people off? But I think it would be a loss to the FE community to not have this info spread to help as many experimenters as possible.

I believe that other than making cores from a non conductive (or high resistivity) material there are only 2 ways to make a core for open magnetic circuits compatible with this realization, one is to have insulated (must be insulated) steel wire, the other is to have magnetic particles suspended in a resin.

Bill Muller made cores with black sand that sound suitable.

zott

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Re: Critical pulse motor core info
« Reply #2 on: March 09, 2008, 03:38:23 AM »
are tou trying to say that a core in the center of a coil is better if it is a solid piece of steel rather than  cut steel welding rods coated in shellac.

Mr.Entropy

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Re: Critical pulse motor core info
« Reply #3 on: March 09, 2008, 03:43:30 AM »
But laminations actually work pretty well.  By Faraday's law, the voltage driving an eddy current around it's loop is proportional to the rate of change of flux through the loop.  If you divide a solid core into 20 laminations longitudinally (so that the laminations are parallel to the flux lines), then the largest possible eddy current loops will have 1/20th the area and will be driven by 1/20th the voltage.

In situations where this isn't sufficient (low inductance, high frequency), non-conductive ferrite or powder-based cores are used.

aether22

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Re: Critical pulse motor core info
« Reply #4 on: March 09, 2008, 04:23:02 AM »
are tou trying to say that a core in the center of a coil is better if it is a solid piece of steel rather than  cut steel welding rods coated in shellac.

No, I am saying that laminations or rods stuck together are little better than solid steel at suppressing eddy currents in open magnetic path devices. (though they work fine in closed path)

An insulated steel coil or insulated steel particles are the only ways to stop induction. (or a stack of insulated cut washers)
Other than of course non-conductive materials such as ferrite's or powder cores as Mr.Entropy mentions.

aether22

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Re: Critical pulse motor core info
« Reply #5 on: March 09, 2008, 05:26:19 AM »
>But laminations actually work pretty well.

They can't possibly if the magnetic field leaks out and with it the induced voltage.
They work just find in closed magnetic systems but if you think about it do not in open ones.

>By Faraday's law, the voltage driving an eddy current around it's loop is proportional to the rate of change of flux through the loop.  If you divide a solid core into 20 laminations longitudinally (so that the laminations are parallel to the flux lines), then the largest possible eddy current loops will have 1/20th the area and will be driven by 1/20th the voltage.


And there are 20 of them!
20 = 20
1 x 20 = 20

Here is another image which will hopefully make it clearer.
note: I made an error and fixed it, also i have made 2 versions, one saved as jpg2000 and the other as orig jpg, both are the same size (the max I was allowed to upload) and of the same content.
no, the .jp2 was not allowed either.
« Last Edit: March 09, 2008, 05:52:22 AM by aether22 »

hoptoad

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Re: Critical pulse motor core info
« Reply #6 on: March 09, 2008, 06:04:39 AM »
@aether
The purpose of laminations (and some other methods) is not to prevent eddy currents, because you can not prevent them. The purpose is to diminish the ability of eddy currents to produce localised non aligned magnetic fields which are mostly counterproductive to the main induced field. The laminations do this because each lamination has an area between it and another, where the electric field produced as a result of induction from the magnet is in the opposite direction to its neighbour. This causes the electric fields to cancel each other out by vector addition +/-, thus inhibiting localised resultant magnetic fields from those eddy currents. Eddy currents would not necessarily be a problem at all if they only followed the direction we wanted them to, but alas, they tend  to follow muliple complex paths.

In the coil, the same cancellation between windings occurs and is called interwinding capacitive loss. But the current induced into the coil which has an iron core is not generated by the eddy current effects of the core, it is generated by the changing main induced magnetic field which is at right angles to each winding along the core. In most of Tesla's high voltage experiments, he specifically left a small air gap between each winding to minimise interwinding capacitance.  You are correct that losses will be incurred using laminations, but they are less than the losses incurred without using them. (compared to solid iron that is)

Cheers
« Last Edit: March 09, 2008, 06:36:53 AM by hoptoad »

aether22

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Re: Critical pulse motor core info
« Reply #7 on: March 09, 2008, 08:28:49 AM »

>The purpose of laminations (and any other method) is not to prevent eddy currents, because you can not prevent them.


I disagree, in a closed magnetic system they are prevented from any real presence because the magnetic and hence inductive force in the laminate core in illustration 1 would be to the left at the top, bottom and middle at the same intensity since almost all the flux stays in, it would be like shorting 2 parallel secondary coils in a transformer, the voltages are equal and opposite so no current will flow.

I also take issue with your claim that there is no way to entirely eliminate eddy currents, it is possible to make a core from a conductive magnetic metal in a non conductive matrix.

>The purpose is to diminish the ability of eddy currents to produce localised non aligned magnetic fields which are mostly counterproductive to the main induced field.

All induction is counterproductive as all of it opposes change. (except in Thane and your designs)

>The laminations do this because each lamination has an area between it and another, where the electric field produced as a result of induction from the magnet is in the opposite direction to its neighbor. This causes the electric fields to cancel each other out by vector addition +/-, thus inhibiting localised resultant magnetic fields from those eddy currents. Eddy currents would not necessarily be a problem at all if they only followed the direction we wanted them to, but alas, they tend  to follow muliple complex paths.

I disagree with the last (an eddy current is induction of electrical energy wasted as heat, therefore always bad)
I will formulate a response to the cancellation argument when I have time, but even IF it is a valid point (and I don't understand it yet) it is still far far better to have less wasted energy induced into the core and the different levels of success of lamination in open and closed magnetic paths IS huge regardless.

>In the coil, the same cancellation between windings occurs and is called interwinding capacitive loss. But the current induced into the coil which has an iron core is not generated by the eddy current effects of the core, it is generated by the changing main induced magnetic field

er, no of course not, how did you ever get the impression I said it was? (if you did)
Although the eddy currents in the core oppose the change in the magnetic field and do reduce the induction into the coil.

>which is at right angles to each winding along the core. In most of Tesla's high voltage experiments, he specifically left a small air gap between each winding to minimise interwinding capacitance.  You are correct that losses will be incurred using laminations, but they are less than the losses incurred without using them. (compared to solid iron that is)

Of course laminations are better than solid core, though IMO for open paths not hugely so. (at least for eddy currents)
And it is possible to do so much better.

What I am saying is that while not perfect in closed and near closed flux paths they work far far better there than in open circuits where voltage is induced unevenly in a lamination and the induced voltages can happy short through a less induced reigon of the same lamination, laminations are designed to stop current flow from one lamination to another but when induction supports a current to circulate in a single lamination it breaks down and become drastically less useful and in such cases better possibilities exist and are mentioned above.

Groundloop

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Re: Critical pulse motor core info
« Reply #8 on: March 09, 2008, 08:48:40 AM »
@aether22,

An air core coil has no eddy current loss. Use thicker magnet wire and more turns to compensate for the weaker magnetic field produced.

Another idea is to use insulated soft Iron wire and make a coil core. Then wind normal magnet wire on the outside of the Iron coil. The
eddy currents produced in the iron coil can then be brought back into your circuit. (Have not tried this method yet.)

Groundloop.

hoptoad

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Re: Critical pulse motor core info
« Reply #9 on: March 09, 2008, 08:48:43 AM »
All induction is counterproductive as all of it opposes change. (except in Thane and your designs)
???

If all induction was counterproductive, then Teslas AC "induction" motor would not have become a standard industrial tool worldwide. Without induction, no motor would run. Without induction you could put as much current through a wire coil as you liked, but it would not "induce" an aligned magnetic field into the metal core.

P.S There is no perfect system, so you will always have losses, be it from heat produced by eddy and load currents, or just plain old rotor windage and bearing friction. There will always be the possibility that better methods for reducing losses exist. Thats what R&D is for.

aether22

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Re: Critical pulse motor core info
« Reply #10 on: March 09, 2008, 11:08:35 AM »
All induction is counterproductive as all of it opposes change. (except in Thane and your designs)
???

If all induction was counterproductive, then Teslas AC "induction" motor would not have become a standard industrial tool worldwide. Without induction, no motor would run. Without induction you could put as much current through a wire coil as you liked, but it would not "induce" an aligned magnetic field into the metal core.

P.S There is no perfect system, so you will always have losses, be it from heat produced by eddy and load currents, or just plain old rotor windage and bearing friction. There will always be the possibility that better methods for reducing losses exist. Thats what R&D is for.

note: I have bolded the key stuff.

I meant induction of electric currents in magnetic cores and I stand by that fact that it is never useful unless Lenz Law on the whole is reversed and CoE no longer applies.
It is never intended or useful, induction motors have copper on the rotor in which current is induced.

Although I can successfully argue that while the induced current is not always counterproductive (in generators and transformers) the counter MMF it creates is NEVER useful even in induction motors since if it were somehow possible for the current to be produced without creating a magnetic field the rotor would still react but the stator would not know any induction had taken place and not be loaded.

I also was not talking about just anything that could be termed induction, the magnetic field induced by a current (not an induced current) is another subject again.

But misinterpretations of what I was saying aside I was not claiming that all losses can be removed (although correctly shaped metglass core with superconductive wire and magnetic bearing in vacuum also aside), what I was saying is that quite simply that the main thing reducing currents in a laminated steel core in an open magnetic circuit is likely the lower conductivity of steel since since the laminations do nothing to stop circling currents as they do in closed circuits although possible paths are limited it is still like having a shorted coil and expecting everything to be fine. (and even in Thanes and your setups it is still best for the electrical energy to be induced in the coil as it can be put to a use)

Nothing you have said as far as I can tell has discounted the fact that laminations provide no straightforward path for induced electrical currents to circulate in a closed magnetic systems (and only imperfections which can be very tiny given high operating efficiency from transformers cause any eddy currents not counting the incredibly tiny field created by circling currents within the thickness of the lamination which is ignorable and now I think about it likely what you were incorrectly referencing earlier).

Whereas the same laminated core in an open magnetic system is like a fat one turn shorted coil made of steel, where as eddy currents might have only caused a few % loss now in the closed path they might account for 50% or higher depending on how much current a pickup coil may be pulling, sharing half the energy with the core posing as a shorted coil sounds like bad practice to me.





hoptoad

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Re: Critical pulse motor core info
« Reply #11 on: March 09, 2008, 12:06:19 PM »
All induction is counterproductive as all of it opposes change. (except in Thane and your designs)
???

If all induction was counterproductive, then Teslas AC "induction" motor would not have become a standard industrial tool worldwide. Without induction, no motor would run. Without induction you could put as much current through a wire coil as you liked, but it would not "induce" an aligned magnetic field into the metal core.

P.S There is no perfect system, so you will always have losses, be it from heat produced by eddy and load currents, or just plain old rotor windage and bearing friction. There will always be the possibility that better methods for reducing losses exist. Thats what R&D is for.

note: I have bolded the key stuff.

I meant induction of electric currents in magnetic cores and I stand by that fact that it is never useful unless Lenz Law on the whole is reversed and CoE no longer applies.
It is never intended or useful, induction motors have copper on the rotor in which current is induced.

Although I can successfully argue that while the induced current is not always counterproductive (in generators and transformers) the counter MMF it creates is NEVER useful even in induction motors since if it were somehow possible for the current to be produced without creating a magnetic field the rotor would still react but the stator would not know any induction had taken place and not be loaded.

I also was not talking about just anything that could be termed induction, the magnetic field induced by a current (not an induced current) is another subject again.

But misinterpretations of what I was saying aside I was not claiming that all losses can be removed (although correctly shaped metglass core with superconductive wire and magnetic bearing in vacuum also aside), what I was saying is that quite simply that the main thing reducing currents in a laminated steel core in an open magnetic circuit is likely the lower conductivity of steel since since the laminations do nothing to stop circling currents as they do in closed circuits although possible paths are limited it is still like having a shorted coil and expecting everything to be fine. (and even in Thanes and your setups it is still best for the electrical energy to be induced in the coil as it can be put to a use)

Nothing you have said as far as I can tell has discounted the fact that laminations provide no straightforward path for induced electrical currents to circulate in a closed magnetic systems (and only imperfections which can be very tiny given high operating efficiency from transformers cause any eddy currents not counting the incredibly tiny field created by circling currents within the thickness of the lamination which is ignorable and now I think about it likely what you were incorrectly referencing earlier).

Whereas the same laminated core in an open magnetic system is like a fat one turn shorted coil made of steel, where as eddy currents might have only caused a few % loss now in the closed path they might account for 50% or higher depending on how much current a pickup coil may be pulling, sharing half the energy with the core posing as a shorted coil sounds like bad practice to me.

@ No arguments here, I'm not trying to convince you that laminations work well or even work at all, I merely put forward the accepted theory.
I have no particular argument with accepted theory on this matter. Whilst I have used laminates in various experiments, I found solenoid cores to be superior for use in my own particular experiments.

With regard to all you have stated above, you may well be right.  :o

But, if your explanations for the behaviour of open magnetic systems ares based purely on theoretical postulations without knowledge derived from hands on experimentation and the resulting data, then you may be falling into the trap of believing assumptions about things which may be proscribed as true in theory but not evident in reality.  ::)

Something to ponder. If a non linear reaction occurs in a system that is meant by the laws of that system to be linear, then can you trust the accepted laws of that system ?. In other words, if the outcome is not in line with the modeled prediction, then which is incorrect, the outcome or the prediction? Setting up virtual models and thought experiments is not the same as setting up real experiments and gaining real data. Test your theory in practice.

I look forward to the results.

Cheers

aether22

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Re: Critical pulse motor core info
« Reply #12 on: March 09, 2008, 12:45:47 PM »
Be that as it may I have no doubt at all that I'm right about this.

It is not worth my time to verify and complication in testing comes from differing permeabilities due to the different ways of dividing the core so that would need to be accounted for.

Though the easiest test would be to make a coil that assumes the shape of a lamination and verify it gets a voltage induced to the expected extent.

Note: Another way to look at it is like this, look at illustration 1, imagine that the coil pictured is producing a north pole up.
Now see that before the flux gets to the other end mach will leave from the sides.
And if we now replace the lamination with a coil of the same shape (or cut the center of the lamination out and now call it a one turn shorted coil) we see that as the flux stength varies so does the level of flux threading our shorted coil and unless the laws of induction are on a break a voltage will be induced, and the critical part will not face cancellation from and other currents.
But in a closed path all the flux leaves through the 2 ends and none of it leaves out the side to induce our laminate coil.



BY THE WAY, THIS THREAD IS A REPRODUCTION OF THE ONE IN NEWS TITLED:
THIS IS HUGE, MUST READ!! All methods to reduce eddy currents useless! -*

IT MAKES SENSE TO HAVE A NOTE OF THIS DISCOVERY IN THE PULSE MOTOR SECTION BUT IT IS A BAD IDEA TO KEEP 2 SIMILAR ACTIVE THREADS SO STOP REPLYING TO THIS ONE AND HEAD OVER THERE.

HOPEFULLY THIS CAN BE MADE STICKY TO STAY AT THE TOP OF THE PULSE MOTOR FORUM

SO PLEASE DO NOT REPLY IN HERE, THANKS
« Last Edit: March 09, 2008, 09:14:56 PM by aether22 »

Mr.Entropy

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Re: Critical pulse motor core info
« Reply #13 on: March 10, 2008, 04:50:33 AM »
And there are 20 of them!
Each dissipating 1/400th the energy or so, because P=V^2/R, and each producing 1/400th the flux (1/20th area * 1/20th current).