Author Topic: Steering Magnetic Fields, Saturated Cores (Read 9730 times)

elgersmad · « **on:** March 26, 2011, 07:13:08 AM »

Ok, these images may be hard to follow. But, they are set up to utilize a permanent magnet inside of a transformer core and drive it into saturation. In the image named Fields.bmp The magnetic field is set up like a Bistable Transistor Circuit. The center post could be north to south or south to north at any given moment. By preference when the permanent magnets are installed which ever one is slightly stronger or makes mechanical contact first will pick the direction of magnetic lines through the center post.

If you have FEMM, the short orange band, is the biasing windings. That coil is used to flip the polarity of center post. In any case north to south can be held in place by the magnet on the far side, and the intersection where the biasing coil is wound is always negligible. Below that is the power out coil. The magnets are chosen for strength to insure that when polarity flips, the core goes into saturation as a result.

The second bitmap image ER.bmp is the same idea except with more paths for the magnetic circuit to complete. The biasing coil is represented by the two circles this time. In FEMM one would be negative and the other positive. Where the orange bands represent output coils that are run either in series or parallel. The whole objective is again to saturate the core and force it to flip based upon the location of a single coil. So, the iron butterfly should be capable of as much. But, that would require custom stampings and laminations, where the other version could be done with a grinder or a hacksaw.

penno64 · « **Reply #1 on:** March 26, 2011, 09:17:30 AM »

Hi Elger,

Can you shed some light on just how much power is required to flip the pole ?

Wouldn't this be wondeful for a motor that only need a spike to SWITCH the pole ?

Kindest Regards, Penno

elgersmad · « **Reply #2 on:** March 26, 2011, 10:19:59 AM »

You don't flip the poles. I just finished writing to a fellow and after researching focusing magnetic fields in gapped magnet, saturation and paramagnetic materials found that you don't need to destroy any cores to do this.

If you take an E core and apply ns E ns with the E core pointing down or up that's all you need. Basically, firing up the primary with any current reduces the inductance to an air core value as if the secondary were shorted all of the time. The primary is then good for a parallel resonant circuit that will oscillate reliably at one frequency. As long as there is not enough current to defeat the magnetic fields, all you do is steer them through the core. From left to right south up over and down through the middle, or from left to right south down and up through the center post. Once the core in full saturation and you have two large neodymium magnets present, that's all that happens. It never falls out of saturation, and the magnets don't require any energy to do the job. Those fields approach the core at a 90 degree angle in respect to the poles that would produced by the windings. So, effectively you won't loose the measure Q value tapping the secondary for energy until you actually do something you can't, which is pull the core out of saturation.

I would highly suggest using ferrite cores or powdered metals due to frequency response. Because, the primary is going to operate like it were an air core coil with just a very slightly higher inductance per turn.

penno64 · « **Reply #3 on:** March 26, 2011, 10:32:13 AM »

Hi Elger,

Thanks for the prompt reply.

I am sure you can see where I was going (maybe).

Plenty of magnets (all sorts) and heaps of ferrite rods, tubes and rings.

I am currently toying with a rotor that, for want of a better term, wants to spin naturally.

That is - on a hdd plater, 16 mags "D" shaped, NS configuration.

The stator is currently 2 x MO fan coils with laminated plates.

I am now trying ferite rod 4" and neo mag at rear (away from rotor).

Again, Thanks for the reply.

Penno

elgersmad · « **Reply #4 on:** March 26, 2011, 12:36:19 PM »

I always cut the circle even vs odd. So, the rotor would have an even number of magnets and the stator just one more. Of course you must divide the circle many many times, and count magnetic lines. I don't know why you would do that. Because, if it did work, it would spin faster and faster and faster until it flew appart. I have heard of such a thing. So, remember that when or if you do that to work include a shorted inductor to place next to the rotor. The closer it gets, the short causes opposition and will slow it down, and in effect act as a speed control.

I've looked into the field situations, and believe that it will and can work with thin neodymium magnets but not the thick ones. No, I haven't built one. But, I did get good look at the Perendeve motor, and at the point that they tried to scale up to a reasonable horsepower, it all fell appart.

teslaalset · « **Reply #5 on:** March 26, 2011, 01:29:07 PM »

Eiger,
Can you post the FEMM model here, please?
I like to have a look at this.

elgersmad · « **Reply #6 on:** March 26, 2011, 11:11:43 PM »

Quote from: teslaalset on March 26, 2011, 01:29:07 PM

Eiger,
Can you post the FEMM model here, please?
I like to have a look at this.

Not at present. It would take me awhile to produce a FEMM model, and it's far easier for me to just order a core and build one. In the time consuming sense, it would take me less time to build an oscillator, measure inductances etc and just build a homebrew sine wave oscillator. Digging around for details and making sure that the software properly models a given material such as Ferrite isn't really easy, and saturation must be taken into account. More current will always result in more magnetic lines, and saturation doesn't stop that. So, FEMM won't really show you time resolved events for AC currents. You would have to fiddle with the software step by step and then produce a list of images to model an actual device. Most models, are fudged somewhat. They really just give you an idea. A complete model includes a list of details that the machine doesn't take into account. There are no special colors assigned for in saturation vs out of saturation. Weather maps have snow colors and rain colors, that doesn't happen FEMM it's free. Free doesn't mean that it can't do that, it just means it takes more tweaking than it's worth.

elgersmad · « **Reply #7 on:** March 27, 2011, 11:54:47 PM »

Update, I did some research and found that when a transformer core saturates, it typically fails. No-one is really looking into controlling saturation or using magnetic saturation. These kinds of situations are often called faults because, the whole system is literally designed around using the available permeability of the core materials for power conversion. They are not being used to steer magnetic fields. There are examples of steering magnetic fields and even at Los Alamos, they have magnetic assemblies that focus up to 14 Tesla into a tiny space. Nobody is looking at steering magnetic fields as a means of generating power. But, that would mean using a core that was pre-saturated and most likely by permanent magnets.

So, I ordered two of these cores:
http://www.surplussales.com/inductors/FerPotC/pdf/ich-e50-15-3c90-g2160m.pdf
http://www.surplussales.com/inductors/FerPotC/FerPotC-2.html#eecore

And five of these magnets:
http://www.kjmagnetics.com/proddetail.asp?prod=BZ084

With the North Pole applied to two halves of the E core on the bobbin and the South Pole applied to the opposite side, the core should be driven into saturation. The center post almost does not matter, but it will be in saturation. Which direction for the length of the post is anybodies guess. The inductance of a coil should retain only the air core value of whatever number of turns. In that sense, I would expect that I could get the north pole or the south pole of the permanent magnets to flow through the center post with just a steering current. The total number of magnetic lines that will move will be or should be from saturation in one direction to saturation in the other. So, to reduce the current of the steering current a high number turns may be ideal over a low number. Here, I would expect that Ampere turns will do more than inductance values.

Winding a coil, isn't a problem for me. But, not breaking the ferrite when I place the permanent magnets already has me thinking about what to do. First the corner of one magnet, then slide it up into position. Then the other magnet. But, you know, if that magnet slams into that core, it's breaking.

theifofthings · « **Reply #8 on:** August 31, 2011, 03:21:40 PM »

Hello! Can you at least draw the specifics about this set up? Because I couldn't really picture out the whole thing with the bulb and the switch

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Author Topic: Steering Magnetic Fields, Saturated Cores (Read 9730 times)

elgersmad

Steering Magnetic Fields, Saturated Cores

penno64

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teslaalset

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