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axial flux in education


By birdhouse, Section Newbies
Posted on Mon Feb 08, 2010 at 04:08:59 PM MST
electrical union training

hello-
a good friend of mine is an apprentice in the electrical union.  he has class once a week and one of the "homework" projects is to create electricity with pre-set supplies.

the supplies:  (10) 1/8 x 1/2 neo magnets and (200) foot of #22 magnet wire and a foot long chunk of 1/4 inch threaded rod.

the rod will be chucked into a 1800 rpm drill along with whatever contraption is atached to it.  additional steel, pvc, supports, ect are allowed but NO rectifiers, capacitors ect.  

the output wires will run to a electrical meter to provide the load.  highest watt rating wins, thus i assume any voltage is allowed.  

i thought making an 1 phase axial flux with dual disks and only using 8 magnets (four per disk) or making it with two rotors, but putting all ten magnets on just one disk.  

any thought?

oh- there is money riding on this..

thanks!
birdhouse
axial flux in education | 9 comments (9 topical)

Re: axial flux in education (3.00 / 0) (#1)
by ghurd on Mon Feb 08, 2010 at 05:24:32 PM MST

Now this is fun!

Define "1/8 x 1/2 neo magnets".
Are they 1/8" thick x 1/2" dia?

With 10 of them, I figure he could to go with overlapping coils on a single magnet disk, and have an empty rotating disk (like the 2nd disk in a dual rotor but without the magnets).

With 10 of them, I figure he could to go with overlapping coils on a slotted laminated core, like Ed's "alt from scratch",
http://www.windstuffnow.com/main/alt_from_scratch.htm

"highest watt rating wins, thus i assume any voltage is allowed"
"NO rectifiers"
That could be THE problem.

Without rectifiers, a standard efficient PMA as we talk about it here can not be measured with a 2-lead meter.
Could measure the voltage or amps on one leg of a 3-ph load and tripple the calculated watts?

"the output wires will run to a electrical meter to provide the load" seems like it could be the trick part of the question.

The other trick part of the question is the 1800RPM.
Is that a fixed 1800RPM from a 50KW motor, or 1800RPM from a $10 100W hand drill?
Not possible to get 200W of output from a 100W drill, making efficiency possibly more important.
If the RPM is fixed at 1800RPM, then a brief high output is more important than efficiency.

"money riding on this"
Feel free to send me $20, unless Mr. Flux responds.
Then send it to him.
G-

Ghurd.info



Re: axial flux in education (3.00 / 0) (#2)
by birdhouse on Mon Feb 08, 2010 at 05:52:06 PM MST

ghurd-
1/8" thick by 1/2" dia round neos.

i don't know all the details of the "rules"  maybe the teacher rectifies it to test for wattage.  i donno.  

so as far as i've heard it's an 1800 rpm hand drill.  probably the 3/8" chuck harry-home-owner style.  

i guess last years students had trouble getting even ten watts, so even twenty watts might win the pot.  i think the pot is $40.  really ghurd- you want half?  :)

that windstuff now alt seems like a lot of work...  though a nice one!

thanks!

birdhouse
"let it blow, let it blow"
[ Parent ]



Re: axial flux in education (3.00 / 0) (#4)
by ghurd on Tue Feb 09, 2010 at 07:13:43 AM MST

The magnet count and size, and wire size, are all a given.
Just need to go with the basics for how they are commonly assembled.

That's less than one cubic inch of neo.  Not much to work with.

The 1/8" thick is the killer.
Almost require an iron core to get anything out with magnets that thin.
Problem is the iron core needs to be within about 1/8" of the neo's face, which does not leave room for much wire and mechanical clearance.
If the 1/8" gap opens more than about 1/8", then the flux drops off fast.

With an air core, the turns more than 1/8" from the magnet face do not count for much power, but they add resistance.
I'd be tempted to make an air core stator with the coils 1/8" thick, kind of splitting the difference to hope for the best.

If they can do and measure 3-ph, need to go with something like Ed's coil arrangement above.  
Could use a plywood ring where Ed uses the laminated ring, for a single disk air core.

Magnet spacing will be important.  1/2" dia should be 1/4" apart for 3-ph.  Willib's files are something to look through.

Then the coil size too,
for 3-ph with overlapping coils, 1/4" wide legs, 1/2" hole, 1/8" thick.  That's about 8 turns wide legs x 4 turns thick.
for single phase,  1/2" wide legs, 1/2" hole, 1/8" thick.  That's about 16 turns wide legs x 4 turns thick.

There is enough wire for a 3-ph, and Way Too much for single phase.
I have a feeling most people run into the idea of using ALL the wire, which lowers the output.

Need to have the neos on iron to do anything.  Maybe a 3" knock-out disk?

Getting 20W is past what I personally would hope for without an iron core.  Gosh, seems like a lot even with an iron core (unless he wanted to do a mini motor conversion- yikes).
G-
Ghurd.info
[ Parent ]



Re: axial flux in education (3.00 / 0) (#3)
by Timeless Turbines on Tue Feb 09, 2010 at 05:22:01 AM MST

     Birdhouse,
I am an I.B.E.W. member, and a AFSCME member, do you know what union is doing this.

Larry
More Power To Ya



Re: axial flux in education (3.00 / 0) (#5)
by frepdx on Tue Feb 09, 2010 at 08:40:22 AM MST

With ten magnets, no rectifiers and a single load/meter you are stuck with a one phase (i think???). Do you have any more details on the load/meter setup?


Re: axial flux in education (3.00 / 0) (#6)
by willib on Tue Feb 09, 2010 at 10:46:54 AM MST

Just whipped this up
It uses 6 coils and 8 mags with a single rotor

http://www.fieldlines.com/images/scimages/2965/02_09_10_8mag_6coil_machine_3.JPG
http://www.fieldlines.com/images/scimages/2965/02_09_10_8mag_6coil_machine_2.JPG

Like G said i would go 1/8 thick or less with the coils.

On a side note:
If he were to use a couple sheets of mylar between the poles and the coils And he made sure that both surfaces were smooth , i bet he could run the mags right up against the coils , for the duration of the " TEST".


Carpe Ventum (seize the wind)



Re: axial flux in education (3.00 / 0) (#7)
by FishbonzWV on Tue Feb 09, 2010 at 01:30:50 PM MST

How about a couple circular saw blades and a wave wound single phase.
That way you could utilize all ten mags on one disk.
Without rectifiers 3 phase is out.
Bonz


Re: axial flux in education (3.00 / 0) (#8)
by birdhouse on Tue Feb 09, 2010 at 05:52:48 PM MST

wow-  thanks for all the replies!  i wish i had more details to give you about wether or not 3 phase is allowed.  my friend has class again on thursday, so i'll ask him to ask his teacher was is and isn't allowed.  

larry-  i'm not sure of the name of the union, but it is the one out of portland, or.  number 48 comes to mind...  pretty cool experiment to be teaching to new electricians!  

will-  thanks for the drawings!  

it seems like most folks are agreeing that using a dual rotor with eight magnets glued to just one disk, and having the second disk rotate with the first.  then using an ultra thin stator with coils around or less than 1/8" thick.    yes?  

thanks again.  more details to come friday!

birdhouse
"let it blow, let it blow"



Re: axial flux in education (3.00 / 0) (#9)
by ghurd on Fri Feb 12, 2010 at 01:29:38 PM MST

Here is a 10 magnet "assembly".
It is something like I was talking about, I have no idea what it is or how it does what it does, but there it is,
http://www.fieldlines.com/story/2010/2/12/1279/75066
G-
Ghurd.info


axial flux in education | 9 comments (9 topical)
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