3 phase magnet placement question

[picmacmillan]

i am confused on how to place my magnets on my steel plates as per hugh's book....i am using 3 phase(4 coils each phase)(12 coils), and 24x1" dia. neo's for magnets...are the magnets layed out concentrically or are they supposed to be staggered and if so, how?..also, because this is a dual rotor what fields(north or south) are supposed to be on each steel plate?  thanks ...randy

[witapple]

"are the magnets layed out concentrically or are they supposed to be staggered and if so, how?..also, because this is a dual rotor what fields(north or south) are supposed to be on each steel plate?  thanks ...randy"

Each rotor should have the magnet faces alternate N-S-N-S and each rotor should be positioned so the magnets look directly at the opposite rotor magnets(thru the stator), so a N pole should be facing a S pole on the other rotor and then at the next magnet a S pole should be looking at a N pole etc etc..

Hope that sounds clear enough.

Dan

[Flux]

Witapple has covered the magnet bit, but if you use 12 coils with 12 poles you will get single phase.

The simplest way to get 3 phase is to use 9 coils ( 3 coils per phase )

Space your magnets equally round the outside of the discs as described above.

Flux

[picmacmillan]

thanks guys....the job is done now....will be testing tomorrow to see what i have for output.......i have 12 coils 3 phase(4 coils in each phase)...my coils are too big and have a resistance of 1 ohm each..my coils are 200 turns of # 18 awg.....i will see tomorrow how much power i can get in star just to see..my magnets are neo's 1" dia...i am on the belief that i will have to redo my stator with alot less turns maybe 65 turns of #15  awg. but if anyone has a been there done that idea, i am all ears......thanks again....pickster

[picmacmillan]

after second thought i may have made a mistake but need your input....i placed 12 magnets concentrically on my steel disc...i didn't check for north south, i just stuck them in their respective jpositions....were each of these supposed to be north south north south etc?..... i made sure that the magnets for the opposite disc were arranged so they would be facing and attracting to each magnet on the opposing disc......they were for sure north facing south etc?....i guess my question would be, for the first disc was i suppose to put one north then the next one south etc...thanks....pickster

[Flux]

The magnets on each disc should go alternately N S N S etc.

With your 12 coils and 12 magnets you must connect it single phase. Series, parallel or a combination of series and parallel.  Don't use a star point. You must also reverse the connections to alternate coils.

You don't get 3 phase by just dividing the number of coils by 3, you also need 120 electrical deg phase difference between the coils of the 3 phases. For this you need 36, 18 or 9 coils.  36 and 18 require an overlapping coil arrangement, 9 will go as a single layer.

Flux

[hiker]

hold a magnet in your hand as you hold it over your rotor--the magnet in your hand

should be attracted to the first mag then repeled by the next--and so on.............

[picmacmillan]

thanks for the help guys...looks like i may be taking my magnets off the rotors ...i hope that adhesive isn't set up yet.......this is a classic case of a newbie trying to get his first genny flying without making sure it's ready yet....to anyone out there that seen this post, if i could do it again, i wouldn't epoxy the magnets down until i am sure my magnet placement is right....one thing i did do was write an "N" or"S" with magic marker on each magnet so i knowwhich they are in relation to the next one.....thanks again guys for the help......pickster

[DanB]

Just some thoughts...

to chime in with Flux there again... if you have 12 poles(magnets) and 12 coils, you've got single phase.  You could run w/16 magnets on your rotors there and have 3 phase from your 12 coil stator, then you'd have 4 in each phase.

Good for testing sometimes, but parallel connections are kind of bad - any misplacement of coils or magnets, or any variation in the windings will cause currents to flow between the coils.  So series is best ...

but - 1 ohm per coil is a lot.  I wonder what voltage your system is?  Be fun so see some pictures of your project~!

[picmacmillan]

i have some pictures to show but i don't know how to get them on here....any idea?

...thanks..pickster

[picmacmillan]

here is the coil.....12 coils in stator...200 turns #18 magnet wire...produces 1ohm of resistance which is too high, recommend less turns...also too thick for those that would like to try it.....

[picmacmillan]

sorry guys i have to figure out how to get my photo's to show up as they are way too large.....pickster