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Author Topic: Smudge's Papers  (Read 460 times)
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While searching for a paper I wrote years ago I cam across several ones of interest so I thought I would post them here.

Here is the first one which suggests that we could have a PM generator consisting of a PM rotating within a coil.  With the coil carrying load current it creates a magnetic field that the PM sees, and that applies drag torque to the rotating magnet.  My idea was to surround the magnet with a superconducting shorted turn that will divert the flux so that the magnet will now not see the flux and therefore will not endure drag torque.  I have since realized that the superconductor must not inhibit the magnetic field emanating from the magnet poles, so it can't be as shown in the paper, but it can be like two shorted turns one each side of the magnet.

I have just done some FEMM simulations where you can set up a diamagnetic material with a mu much less than unity (I used mu = 0.001) and that simulates the superconductor.  The first image below shows the Lenz field from the coil as directly applied to the magnet (the magnet's field is not shown in this view as that distorts the picture).  The torque as calculated by FEMM is positive, an arbitrary figure here.  The next image shows the effect of having superconducting material either side of the magnet, the Lenz field is diverted around the magnet.  I expected the torque in this situation to be much reduced, but to my surprise it actually reversed.   So it appears that we can make a generator where the Lenz flux from the load current creates a boost torque, not a drag torque.  Now that is something to think about.

Edit.  I should point out that I checked that the presence of the superconductors did not reduce the magnet's flux coupling to the coil, so it would still generate voltage.

Smudge 
   

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Here is the first one which suggests that we could have a PM generator consisting of a PM rotating within a coil.
Rotating around which axis ?  Could you add some arrows to your diagrams ?

...and that applies drag torque to the rotating magnet.
Is the magnet itself electrically conductive ?
   
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Rotating around which axis ?  Could you add some arrows to your diagrams ?
OK, here are the same images with the rotation denoted, with the field arrows and the magnet poles marked.  Also I have added a 3D view of the model showing the dimensions I used to get those torque figures.
Quote
Is the magnet itself electrically conductive ?
I used the NdFeB 52 MGOe model available in FEMM, but I was only looking for some guidance as to the effect of shielding the magnet with superconducting material, so the conductivity of the magnet didn't come into it.  FEMM gives a snapshot and I chose the point where the magnet's coupling to the coil is going through zero, the output voltage and load current is maximum hence drag torque is maximum.  This was not a dynamic run, I just used 100 amp-turns in the coil as a load current.  Quite probably the conditions needed to get this would be an impossible rotor speed, but I was looking for the principle.  I was surprised to see the drag torque become a boost torque, but that may be a simulation artifact.  FEMM uses the Maxwell stress tensor for its torque and my reading on that subject tells me the stress tensor ought to be taken close to the surface of the rotating  magnetic object.  FEMM doesn't do that, it creates a stress tensor mask some distance from the surface.

My next step is to do some full dynamic runs using FEMM.  In keeping with the title of this thread I attach my paper describing how FEMM can be used for dynamic modelling.

Smudge
   
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Well I checked out the stress tensor mask used in FEMM for obtaining torque, and it is very susceptible to the mesh size.  When I increased the mesh (reduced from 2mm down to 1mm spacing) the reversed drag torque disappeared.  It became drag, not boost torque, of significant amplitude so my idea that the superconductor would shield the magnet didn't work.  To explore why, I put a thinner magnet inside the shield so that I could have an air space around the magnet (the stress tensor mask has to be through air).  I could then examine the torque on the magnet itself and low and behold the magnet was screened by the superconductors, there was little torque on the magnet.  The drag torque had all transferred to the superconducting screens.  That gives me a problem because when I consider the currents induced into the superconductor (or in the case of a highly diamagnetic material the alignment of the atomic dipoles therein that make it exclude the field) I can't see how they can carry that torque.  The stress tensor approach calculates torque as though the magnetic field itself carries that mechanical torque, but there is no matter there in that field.  In my mind the only place where the mechanical torque can materialize is on matter itself, or rather on the atomic dipoles within that matter.  I think I need to do more to see how the complex field pattern that exhibits torque via the stress tensor really does tell us the torque on those atomic dipoles.
Smudge
   
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Not sure if I have posted this before, but here is my explanation for the ball-bearing motor.  It relies on the bearing being of steel and therefore ferromagnetic where conduction electrons can be spin polarized.  Current passing through the ball transports angular momentum.

While on the subject of spin polarization here is another paper offering an interesting experiment that may offer OU potential.

Smudge
   
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Here's another paper that I partly wrote some time ago and have just completed.  It's for the TPU buffs as it describes how a TPU could get energy from the Earth's field, and in particular the Earth's scalar magnetic potential which has a huge value away from the equator.  It can explain a lot of the known facts about the Steven Marks TPU, like its gyroscopic feel, its inner coil (maybe not a coil) wound onto a cork former and it won't work upside down.  Doesn't fit with Marks 5KHz frequency though.  Enjoy!
Smudge 
   
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And now for something different.  This paper shows three images.  The first image shows a how two magnets where their axes are always parallel can have attraction and repulsion zones.  At the dividing line between these zones, the so called neutral line, the linear force is zero but there is a strong torque.  The second image shows how one magnet can follow a circular path where the linear forces provide a driving force around that path.  Of course it requires something to keep the axes parallel.  The final image shows the Ferris wheel motor where gravity is the force that keeps the axes parallel.  Worth building?
Smudge 
   
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This suggests that the Bearden MEG relies on magnetostriction of the metglas core coupled with the saturation of the inner laminations so as to make use of the Villari effect.   The core will have an ultrasonic resonance.
Smudge
   

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Believing in something false doesn't make it true.
And now for something different.  This paper shows three images.  The first image shows a how two magnets where their axes are always parallel can have attraction and repulsion zones.  At the dividing line between these zones, the so called neutral line, the linear force is zero but there is a strong torque.  The second image shows how one magnet can follow a circular path where the linear forces provide a driving force around that path.  Of course it requires something to keep the axes parallel.  The final image shows the Ferris wheel motor where gravity is the force that keeps the axes parallel.  Worth building?
Smudge

Thanks for the interesting paper.  My testing confirms what you have posted.  I like your idea for the Ferris wheel version.  I am currently working on my own magnet motor idea.  If it doesn't work out I will probably attempt to build your Ferris wheel version.

Carroll


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Just because it is on YouTube does not make it real.
   

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You’ve been doing my head in all afternoon with Ferris wheel structures smudge  O0 ;D ;D ;Di
   
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