Mostly Permanent Magnet Motor with minimal Input Power

[gyula]

Hi Luc,

If you observe the current consumption of a conventional electric motor, starting from a standstill to its unloaded full RPM, what would you find? Just at startup the current is at its highest value of the whole range (range here is from 0 RPM to full RPM, unloaded shaft), then the current gradually gets reduced as the RPM increases. Why does the current decreases? You surely know: the current decreases due to the back EMF which gradually increases as the RPM increases and works against the input EMF. But the result of the increasing back EMF is a decreasing current consumption because the two EMFs work against each other and their instantenous difference is that can only maintain current. And this EMF difference is surely much less than the input EMF itself. You may consider the back EMF as an RPM dependent voltage source, always in counter or opposite polarity wrt the input EMF.

The same thing is valid for your setup. When your coil starts moving its current consumption will only be dictated by the friction which is already a constant and given value and also by the coil mass, also a constant and given value already. When you stop the coil, it will have the maximum current consumption because in that moment there can be no back EMF develop in the coil. And when you let the coil moving again, the current immediately starts reducing to the "normal operational" value you correctly express as "The faster the coil is moving the less power it consumes."
(And the normal operational current consumption i.e. the no load consumption for your setup is established by the friction and coil mass.)

You can certainly reduce friction but not readily the coil mass. To reduce coil mass you are forced to use even more powerful magnets and also use higher wire diameter to reduce copper loss. So you ought to meet contradicting requirements: reduce coil mass versus using higher diameter wire that involves more mass eventually. Somewhere you have to find a tradeoff.

Hopefully it is clear for you now.

rgds, Gyula

Hi Gyula,

thanks for taking the time to calculate all this and posting it.

You're right! the coils inductance was taken without the steel bar in it. I'm so use to only using magnets in the coil (which has next to no change on coil Inductance) I forgot about the steel. So it's much more now. I measured 103mH when the coil is in the center of the bar and works its way down to 66mH when it's at the magnet (end of bar). Same measurement on each side.

Added:

Gyula,

I just did a new test. I attached my voltmeter to the coil to read the voltage when the coil is moving (attraction) from one end of the bar to the other. I used my variac through a FWBR and 3900uf cap and set the voltage to 1.50vdc with coil attached and held in place. When I let go of the coil the voltage rises to 3.03vdc during its travel across. I then used a D cell 1.5vdc battery and attached it to the coil and also attached my quality amp meter and repeated the experiment above. I connected the battery and held the coil in place and the readings are 1.51vdc @ 189ma. This seems to be the maximum power the coil uses at this voltage. I then disconnected the coil to relieve it for a few seconds. I let go of the coil and reconnected to take the readings while in movement. They are 1.53vdc @ 55ma (average ma after many tries) which = to 0.08415 Watts.

To me it looks like the coil has an advantage while it's in movement, so I'm not sure what Peter was trying to say (The faster the coil moves, the more the coil will generate back EMF to counter your input. THIS is the process that limits the overall efficiency)

It doesn't look like anything is countering the input it looks quite the opposite. The faster the coil is moving the less power it consumes I do agree that under load it will consume more power which is understandable but I don't understand the above statement.

Do you know what Peter is trying to explain?

Thanks for your time

Luc

[gotoluc]

Hi Luc,

If you observe the current consumption of a conventional electric motor, starting from a standstill to its unloaded full RPM, what would you find? Just at startup the current is at its highest value of the whole range (range here is from 0 RPM to full RPM, unloaded shaft), then the current gradually gets reduced as the RPM increases. Why does the current decreases? You surely know: the current decreases due to the back EMF which gradually increases as the RPM increases and works against the input EMF. But the result of the increasing back EMF is a decreasing current consumption because the two EMFs work against each other and their instantenous difference is that can only maintain current. And this EMF difference is surely much less than the input EMF itself. You may consider the back EMF as an RPM dependent voltage source, always in counter or opposite polarity wrt the input EMF.

The same thing is valid for your setup. When your coil starts moving its current consumption will only be dictated by the friction which is already a constant and given value and also by the coil mass, also a constant and given value already. When you stop the coil, it will have the maximum current consumption because in that moment there can be no back EMF develop in the coil. And when you let the coil moving again, the current immediately starts reducing to the "normal operational" value you correctly express as "The faster the coil is moving the less power it consumes."
(And the normal operational current consumption i.e. the no load consumption for your setup is established by the friction and coil mass.)

You can certainly reduce friction but not readily the coil mass. To reduce coil mass you are forced to use even more powerful magnets and also use higher wire diameter to reduce copper loss. So you ought to meet contradicting requirements: reduce coil mass versus using higher diameter wire that involves more mass eventually. Somewhere you have to find a tradeoff.

Hopefully it is clear for you now.

rgds, Gyula

Thanks Gyula for the details.

It looks to me like all motors will have BEMF occoring is there a way to prevent it? or even reduce it? that has proven to be better then a motor with BEMF?

Thanks

Luc

[gyula]

Hi Luc,

Well, to answer your question, Peter Lindemann's rotary attraction motor that contains iron cores and electromagnets only and does not contain permanent magnets, is one possibility I am aware of.

There is another design I saw at overunity.com from member DMMPOWER, see this link: BEMF MAGNO MOTOR
He claims for his setup a no BEMF case which may come about due to the repel fluxes between the 'rotor' and 'stator', no induction can occur in that case? It would be very good to discuss his theory here.

rgds, Gyula

[cody]

Very good bemf explanation gyula.

luc, your correct all motors have bemf. In fact every coil has bemf just by powering it up, you cant get around that. But in a motor you can reduce it by simply getting rid of the magnets. That way the only bemf your fighting against is the coils bemf. Like Peters design. You could alter yours to be like Bob Teals, with the coil attracting a piece of iron through the center of the coil and have the same no bemf operation. I have also heard stories of using exotic flux paths but im not really sure how that works or if that was directly related to a bemf effect. But maybe your energy recovery will be good enough in your design to overcome the bemf losses. That slow speed is just itching to put your recirculating effect on it, im sure youve been thinking about that already

[gotoluc]

Hi folks, Hi gotoluc,

What

What this means is that when at higher rpm your magnetic field will be less and so less shaft power due to the reverse generator built in, though at lower rpm's you can have higher efficiency, but still may be limited since the reverse gen effect is still there. So if we could use magnets and not have this reverse effect then at max rpm the torque and shaft power would be large, whereas in most motors now its feable until you lower rpm which allows more current to flow because less reverse voltage. hope that helps.
peace love light
Tyson

Hi Tyson,

thanks for the explanation

If I was to use this motor design I would use it at a very low RPM (1 Hz or less) since it has more mechanical power when running very slow. If I would of dropped the frequency of the motor in my video (test 1) the coil would slap the magnets much harder then you even heard the time it started doing it. I think I'll do tests to see how long of a shaft I can have before the coils mechanical efficiency starts to drop since much is lost when the coil reaches the end and needs to reverse.

Luc

[gotoluc]

Gotoluc - is your engine generating current unpowered in the same direction as you would use to move the coil by powering it? Ie; the wires are the same polarity?

Yes Inquorate! same direction. If it was the opposite it would not drop in power when it would move forward.

If that is the case (and I'm no expert) then the counter-emf people are talking about would in this case be supporting-emf???

That's what I was trying to get to the bottom of

Luc

[gyula]

Thanks cody.

When you have some freetime would you go through the link I gave on the no BEMF claim setup by DMMPOWER? I would be interested in reading your understanding on his both the DC and AC case setups.

Luc, to test in the simplest way DMPOWER's claims (i.e. no induction can happen between two electromagnets in repel mode, this would mean no BEMF), an experiment could be done as follows: take two more or less identical electromagnets (meaning equal number of turns and identical core materials) and connect them in series and face two endings in repel mode. Then move one of them passing in front of the other (defeat the repel force with your hand movements) and see the current consumption how much it changes. The best would be to use a DC source like a battery with an DC ampermeter in series with it or a DC power supply also with a DC ampmeter.
If DMMPOWER claims is correct then the current consumption cannot change (maybe only a very little, depending on the difference in the electromagnets), and when a current does not change (or changes a very little) in such a setup where repel fluxes interact while the coil or coils moving, then it would be very good news I think.

Maybe I do not consider or misunderstand something in the above description, anybody feel free to discuss if so.

rgds, Gyula

Very good bemf explanation gyula.

luc, your correct all motors have bemf. In fact every coil has bemf just by powering it up, you cant get around that. But in a motor you can reduce it by simply getting rid of the magnets. That way the only bemf your fighting against is the coils bemf. Like Peters design. You could alter yours to be like Bob Teals, with the coil attracting a piece of iron through the center of the coil and have the same no bemf operation. I have also heard stories of using exotic flux paths but im not really sure how that works or if that was directly related to a bemf effect. But maybe your energy recovery will be good enough in your design to overcome the bemf losses. That slow speed is just itching to put your recirculating effect on it, im sure youve been thinking about that already

[gotoluc]

Luc, to test in the simplest way DMPOWER's claims (i.e. no induction can happen between two electromagnets in repel mode, this would mean no BEMF), an experiment could be done as follows: take two more or less identical electromagnets (meaning equal number of turns and identical core materials) and connect them in series and face two endings in repel mode. Then move one of them passing in front of the other (defeat the repel force with your hand movements) and see the current consumption how much it changes. The best would be to use a DC source like a battery with an DC ampermeter in series with it or a DC power supply also with a DC ampmeter.
If DMMPOWER claims is correct then the current consumption cannot change (maybe only a very little, depending on the difference in the electromagnets), and when a current does not change (or changes a very little) in such a setup where repel fluxes interact while the coil or coils moving, then it would be very good news I think.

rgds, Gyula

Hi Gyula,

I can do this test. Does the core material matter? Can it be coreless?

So, I bring them together (repel mode) then move one from side to side and see if the power changes, correct?

My motor design is also in repel mode but made from the PM! is this not similar?

Luc

[gyula]

Hi Luc,

The core material cannot matter, and yes I think it can be coreless too. With iron cores the conventional negative effect i.e. coils interaction due to the movement would be more pronounced.

Re on the your bringing them together: yes, treat one coil as the rotor, the other one as the stator and try passing the rotor in front of the stator, beyond the face to face position too. Try moving both to increase the relative speed, so that induction, if any, could surely take place between them (if any induction may happen at all of course).

Yes, your motor design is also in repel mode but this is the only similarity, nothing else: you have one coil and PMs and this setup have two coils in series and the same current flows through them and no PMs, this is a huge difference I think.

Gyula

[h20power]

Well done,
Now to put that in the place of a piston on a engine and see just what it acan do.


h2opower.

[cody]

gyula,
I took a look at the link. I dont think its a no bemf design and ill explain why i think that. He is using say a N field electromagnet to repel a N field electromagnet right. This is the same operation used in a bedini monopole except bedini has a permanent magnet. It should not matter if the N field is made by a permanent mag or by an electromagnet, either way its still a N field. Therefore this N field (whether by perm or electro) moving away from the stator coil will still produce bemf in the stator. But maybe i misunderstood something in his diagram.

edit
I looked at the diagram again and now im just confused...... I dont know really, i guess someone should test it to find out.

[essamali]

very nice idea

i this this motor is working like the car motor working same idea right

[gotoluc]

Hi Luc,

The core material cannot matter, and yes I think it can be coreless too. With iron cores the conventional negative effect i.e. coils interaction due to the movement would be more pronounced.

Re on the your bringing them together: yes, treat one coil as the rotor, the other one as the stator and try passing the rotor in front of the stator, beyond the face to face position too. Try moving both to increase the relative speed, so that induction, if any, could surely take place between them (if any induction may happen at all of course).

Yes, your motor design is also in repel mode but this is the only similarity, nothing else: you have one coil and PMs and this setup have two coils in series and the same current flows through them and no PMs, this is a huge difference I think.

Gyula

Okay Gyula,

the test is done!... I had 2 identical 120v to 15v step down transformers which I broke open and cut the end of each to make an open E core of each. The primary (120v) is 40 Ohms @ 153mH (cut open to E) and secondary is 0.6 Ohms @ 1.16mH

I used three 12vdc batteries in series to get 36 volts as power source and passed the + through my quality 6 digit meter to measure amps. I connected the primaries of the transformers in series and they were repelling each other. Once they were together I slide them apart many times as fast as I could (by hand) and kept my eyes on the amp draw. I could not detect any change at any time. I also tried it with the secondaries in series but with 12vdc @ 7.23 amps and also the same results.

Keep in mind that power was connected at all times!... if that changes anything

Let me know if this sounds alright to you Gyula

Luc

[gyula]

Hi Luc,

How fast you are! Very good and many thanks for this test. Yes your test sounds ok to me (I assume that connecting the primary coils in series resulted in a current consumption of about half an Amper from the 3 12V batteries.)

Now we have to understand the setup DMPOWER showed in his drawing. You have made a DC test and DMPOWER's first drawing shows the DC setup where two - two electromagnet pairs are shown. He seems to indicate brushes at the center shaft of his drawing for switching the current on and off when it is just needed. Thinking loudly, maybe more than two-two coil pairs would be needed for a smooth operation and all these coils are to be connected in series, to run the same current through them. And because of the repel forces being the strongest when the coil pairs are just facing and these repel forces act radially towards and away from the shaft, we should fix the coils in an angled (twisted) position to utilize the repel force the most in the wanted rotation, and leave a minimal force towards the shaft.

Of course, first two-two coil pairs (four electromagnets) would be enough for building a pulse motor for testing purposes.

Let's try to understand what happens when you load the shaft of such a pulse motor? After your test it is sure that the current consumption cannot increase for the shaft loading because there is no induction backwards we have got used to it so well, very unusual property, no? The RPM would probably get reduced but input power would remain more or less the same.

I think this is the next step for testing. I cannot be 100% sure this setup will be giving out more power than what is needed to run it, sorry for this, this setup is also new to me, I also have to fully understand its properties, including the AC feeding behavior too. Any other member here are welcome to comment.

Thanks Luc!

Gyula

[gyula]

gyula,
I took a look at the link. I dont think its a no bemf design and ill explain why i think that. He is using say a N field electromagnet to repel a N field electromagnet right. This is the same operation used in a bedini monopole except bedini has a permanent magnet. It should not matter if the N field is made by a permanent mag or by an electromagnet, either way its still a N field. Therefore this N field (whether by perm or electro) moving away from the stator coil will still produce bemf in the stator. But maybe i misunderstood something in his diagram.

edit
I looked at the diagram again and now im just confused...... I dont know really, i guess someone should test it to find out.

Hi Cody,

Thanks for the answer. You seem to go through the same frustration I had when first pondered on this setup. You are right that in Bedini's setup a permanent magnet creates the same N field like an electromagnet does. But one thing is totally different: when you switch the current off in the perm. magnet case, the total field of the perm magnet remains there in its same strength whereas in the two electromagnets case (no perm magnet) both N fields collapse because the coils near to each other are fed by the same current, and both fields still repel each other during the collapse, so back induction cannot really take place in either direction. With a permanent magnet present, its field can immediatly penetrate into the coil and/or to the coils core when you switch off the current in the still nearby electromagnet.

I do think this is an important and useful property but fully agree that it should be tested in pulse motor setup.

Thanks, Gyula