Triangular Coils

[WXYZCIENCE]

I made a new jig to hold the triangular coil. It is made from 1/2" polyethylene.





This first test coil has 35 windings of #14 guage copper.







I mounted the test coil to my work bench and positioned the rotor in place.







The aluminium bracket is sitting on a rubber pad for this test.







Pictured here are holes drilled into the steel disk to high speed balance the rotor. Earlier today I balanced the rotor and added epoxy to secure the neos in place. At the speeds that this unit will operate at, there is no value in losing a magnet or two. I have not figured rim speed yet, but it is moving.







This frequency meter was reading 558 hz. So (558x60) = 33480 divided by three (the number of north poles) 11160 rpm.







This last picture is of a 60 watt 12 volt light bulb lit by one coil. The flywheel action only lasts a couple of seconds after I energize the unit to ~11000 rpm. Good enough for the test of this coil. I will now wind some different coils just for the fun of it.
Any comments welcome.
Joseph.

[willib]

its a shame 6 isnt evenly divisible by 4 for a three phase machine.

but that is what you have so, how many coils do you want to use?

how about four round coils , about 2" dia with a half inch hole

it could be a two phase machine.

your ID on the rotor is about 3.864 " dia?

how thick are your coils now?

to get the most from the magnets it is preferable to present as much copper area as possible to the magnets.

this way you can make them thinner,

they dont have to be the full 2"dia , 1.875 would be close enough.

and round is easy to wind

the reason this will work is your neos are square ,

[willib]

what is the open circuit voltage at 11000 RPM

how or what did you use to get it spinning at 11000 RPM

i think you are breaking new ground here , long ago i thought of using a " wren turbine " as a powersource for a alternator.

they can spin at 195 thousand rpm  full throttle , and use ceramic bearings

[DanB]

I wonder if eddy current losses might start becoming an issue in fairly thick wire at such high frequency.  Do you detect any heat in the machine if you run it at such high rpm for a while with no load on it, or is there any noticable torque on the stator when it's unloaded?

Probably not an issue..  but Im curious.

[DanG]

I think a impulse-steam turbine and your VTR rotor should be introduced; maybe neo-magnet coupling & disconnect so it is not subject to the full heat load of steam, also using water as cooling in pre-heat loops. Every time I think of the VTR unit I think of WXYZCIENCE's steam unit - it would be neat to have a small modular unit w/ dongle that gets dropped into a campfire and have electrical charging from....

[tecker]

Looks like you could be a little taller on ythe legs and squeeze a little more from that coil.

[WXYZCIENCE]

DanB, at 558hz the rim speed is ~195 feet per second or ~133 mph. What I have found is that if there is any heat from the coil it is lost because of the fan effect caused by the magnet slots. Open circuit volts on the coil was ~14 volts. Loaded with the 60 watt bulb the loss was ~1.4 volts. 12.6v x 4.76a = 60w Loss 1.4v x 4.76a = 6.6w. I get eddy current vibration when the air gap is less than 1/ 16".


I goofed and connected the amp meter across the coil, it red over 25 amps. I will try not to do that again. I need more tests with better speed control.


We have another exact head and Bill is building one with only four poles. We will compare that configuration with the six pole.
Joseph

[tecker]

The thing about smaller rotors and especially really small the bond between two opposing rotors is all that's nessary to keep them aligned even at high speed . You can crowd the center with your wire .I know that's not news but makes a solid stator with the wire closing at the center.

[WXYZCIENCE]

Willib, the method is a little crude but it works. I will be adding a 1HP dc motor to the test bench to run the unit up to the rpm needed today.







Four to one increase from the 3100 rpm. Extreme science?
Joseph.

[RP]

Since you have such a small diameter I wonder if you could use a criss cross wave winding scheme.  Instead of crossing back out to the outer edge again, you'd simply cross to the opposite magnet.  Since that magnet is the opposite polarity and moving in the opposite direction, it'll add to the voltage without cancellation.   Doing it this way at least gives you nice straight triangular legs.

The image shown here is single phase but does not take coil leg width into account. Perhaps it would be possible to achieve 2 or even 3 pahse this way.

[tecker]

yes in deed

[Lumberjack]

The problem that crops up is what to do with the center shaft...Also as the inner diameter increases the wire length becomes too long.