please help ghurd or anyone about axial flux

[awk]

 
magnets: 1.18inch 5mm thick

rotor:10 inch

blades:6 feet diameter

wind speed 10 mph average

a dual rotor system 12 mag on each rotor with 9 coils.12v system.

 i want to ask about what gauge and how many turn of wire do i use for 12 v system.

[prasadbodas2000]

I have same sized (same rotor, blades, windspeed, batt volts, number of mags and coils etc) machine but with 2inch by 1inch by 0.5 in thick N35 magnets. I used to get 12 V DC BAtt volt match at about 120-150 RPM in 10mph-ish winds with following coil config
start connected 3 ph bridge rectified
55 turns each of the 9 coils, 16 gauge

in your case magnet size is not completely given (is it 1.18 x 1 x 0.2 inch size magnet?). Assuming to be so ur magnet mass is mass is 23.5% of mine - hence I expect (suspect) that u need 1/0.25 i.e. 4 times the number of turns as mine - i.e. 220 turns. So u need to find out the best suited wire gauge which will allow u to fit in the coils with these many turns.

HTH

[jimovonz]

Awk, this is the third time you have asked this and the second time you have started a thread on it. You have not replied to any of the comments in these threads and it almost seems as though you are not reading them either. I suspect you are going to run in to trouble with one of the moderators shortly... Unless there is someone out there who has used the exact same configuration, you are not going to get an answer. Those magnets are not common here on the board so I don't like your chances. You need to construct the magnetic assembly and make a test coil to get the answer you want I doubt that anyone here is inclined to do it for you.

prasadbodas2000, calculating turns using the ratio of magnet volumes is never a good idea - especially as in this case Awks magnets are a different shape (round), unknown strength and with an unknown air gap.

[prasadbodas2000]

Yes Jim. It did not click to me that AWK was refering to round mags. Also magnet grade will be a big factor.(NOW I even start feeling if AWK is having NdFeB mags or even ferrites......)
In any case as you already said rightly, best is to make a setup and try out a test wound coil.

[TomW]

awk;

Please have the common courtesy to at least read the replies already given to your previous questions.

Posting replies to those previous threads would go a long ways to helping yourself

We love to help but we dislike spoon feeding when the one being fed spits it on the floor.

Do NOT start new threads on the same question.

Tom

[tecker]

You really need to get the books .I see your mags may no fit the common profile so consider stacking the mags if you can . If you just have 24 mags. space them evenly around the parimiter of the rotor plates .  The best way to get the  mag/ coil spacing right is to make a 12 segment pie chart and bisect the the 12 segments for your magnets  that gives a coil with  ~1.25 inche core and ~3/4 inch legs keep the thickness to 1/4 inch when making your winder and make a coil to test with and resend your findings for total calutaion . With square mags your coils will be round consider a triangle shape that will turnout almost oblong when wound .

[awk]

sorry about posting my question again and again 

let me make things clear
my magnets are N35 neo 1.18inch 5mm thick.ROUND SHAPE.
dual rotor 12v system.rotor diameter is 10inch.
i have goggled about stator thickness it should bi about 10mm or 1cm thick.
I have calculated about coil thickness and width they are about 8mm thick and 6cm wide.
i am new with the coiling stuff so need a little help about gauge and turns.

thanks.

[awk]

thanks tecker about  info but at what size and turns should i start.

[awk]

@prasadbodas2000
 here is my neo magnet.

[kurt]

it does not matter what size wire you use to wind your test coil as long as you know what size it is within reason same for number of turns just wind the coil to the shape and size that fits your magnet spacing be sure to count the turns as you will need that info. then temperately mount that one coil between the magnet rotors you have constructed with the airgap (distance between magnet rotors) you want to use wire the two wires of the test coil to a multimeter set on low a/c volts and spin the rotors at a known rpm and measure the voltage.

then come back here and post number of turns, size of wire, voltage, and rpm and we will be able to help you.


i cannot put it any clearer than that.  

[tecker]

 2 strands of 21 awg(.7 2 mm ) 60 turns . Tape the outer perimeter of the coil so it can be siliconed in place looking for 3 volts at 250 rpm if  the voltage hits in at lower rpm you have choices to remove some turns now or cut down the blades later . I don't think the 3 foot blades will stall and I don't think the mags will over heat the stator  with 2strands  of 21 . Again looking for elongated coils .

[wooferhound]

There is some information in this FAQ about Coil size that should help you . . .

http://fieldlines.com/board/index.php/topic,143575.0.html

[willib]

Awk, magnets of that dimension would be best used in a 12 coil 16 pole machine if your rotors are at least 10.6 inches in diameter.

Otherwise a nine coil , 12 pole machine will fit with a rotor diameter of 8.26 inches in diameter.

Coil diameter is twice the magnet diameter.

[Flux]

This is very approximate, I have no experience of round magnets but basing it on 1" square ones I think you can get 16 poles on a 10" disc. From Willib's figures you will have to squeeze the coils a bit elliptical to get them in but it won't matter much.

Much depends on the prop you use and its tsr but using a reasonable wooden prop I think you have enough magnet for a decent 5ft machine.

Try your test coils with about 30 turns and I suspect you will get something like#15 in that space.

You will need to do a test coil as others have described and you will have to base things on your chosen cut in speed and that depends on the prop.

If you must go for a very slow pvc prop then you will need a lot more turns as I based cut in on something like 250 rpm. With a slow prop you may have to reduce diameter or furl very early indeed with 5ft.

Based on the cut in speed and size of prop I mentioned you will have a machine capable of about 300W but if you go for lower cut in your rating will drop.

Flux

[ghurd]

Just for the record, I am not good at designing axials.
I reverse engineer them, or ask people who know a lot more than I know.
And mine do not turn out all that well anyway.
G-

[awk]

i have made some calculation on rotor and stator
my rotor is 10inch in dia
12 magnets on each rotor
it means every magnets is at 30 degree angle
now when i calculate about stator it show that when i use 9 coil they donot distribute equally.
now i am using 12 coils for 12 mag.my coil shape is round inner radius is about 3cm and outer radius is 6cm coil thickness is about 8mm.
i will wind my coil from 15 awg wire then post results.
thanks for help and support.

[jimovonz]

Awk, the ratio of magnets to coils needs to be 4:3 so for 12 magnets you need 9 coils. The coils will be distributed evenly around the stator at 360/9=40 degree intervals. This setup gives us our 3 phases. If you use 12 coils with 12 magnets you get single phase.

[willib]

I mean no offense AWK , but ya cant cant just arbitrarily change stuff and expect it to work.
what do ya mean when ya say that  'they don't distribute equally'?
As Jim said the ratio of coils to poles is 3/4 .. period. If you want a three phase machine..
Technically speaking if you wanted a single phase machine you need twice the number of poles as coils so that each coil has two opposite poles traveling over each coil at the same time .

But single phase is a waste of magnets and wire.. and they do not run as smoothly as a three phase..

I see now that this thread should have been posted in newbies section.

Be that as it may , My advice is to study three phase axial machines like at  Ed Lenz's site..

[TomW]

I see now that this thread should have been posted in newbies section.
 

I just fixed that oversight.

Tom

[tecker]

 Interesting transition from good approach to introspective  .Hang in there the S@#%$@ is the next Phase but if you go back to the original focus you can bring it back .Single col tests are very good and fun moves in the right direction the rotor is in the perk . You can carry on

[awk]

@jimovonz
u are right coil area it is at 40 degree angle.
 but  i goggled about coil size, my magnets are 3 cm in dia and coil should bi 6cm in dia with a 3cm hole in centre for magnets.

but 6cm coil is not coming in 40 degree angle i mean i need a bigger radius coil for giving it in 40 degree .
any suggestions...?

what coil size do i choose?

[Flux]

What is the problem?

I can't remember all the details but with 10" discs and 3cm diameter magnets, if you put the magnets near the outside the spacing is such that 6cm coils work out near enough right.If the magnets are right at the edge of the disc then you will have gaps between the coils. Does this matter? if so you have 3 options:-

Make the coils bigger, make the magnet radius less than the biggest for the disc or live with gaps, it works either way. You have magnets spaced at 30 deg and the coils spaced at 40deg. If you have 9 coils equally spaced they must be at 40 deg.

There is no law that makes you stick to the 6 cm outside diameter but if you want to then it doesn't matter that the coils don't touch. Personally I would keep the magnets at the outside and increase the coil outside diameter until they touch ( or very nearly so).

There is no exact science in any of this, it's going to be a very tiny machine anyway, I did my calculations on 16 magnets so if you drop to 12 then the maximum output will fall quite a lot and the speed will need to go up to take the smaller blades needed for the smaller power.

You are now looking at something no bigger than 4 ft blades and a cut in of 300 plus rpm for wooden blades. With slow plastic blades the speed will need to drop and output will be very low.

Flux

[awk]

@ flux
now i understand that there is no need to touch coil outer radius but giving some more turn i will touch them equally.

you said 16 magnets on one rotor, problem is that i have only 24 magnets for 12 on each rotor.
would i make a single rotor system with 16 magnets to increase power? i need at least 100W in 10mph wind and maximum would bi 400 W in 25mph.

and i thing more i have pvc 6 feet dia blade i know they are not capable for producing much power. i would increase length by 8 feet dia.
my aim of cut in speed is about 8 mph wind what length of both pvc and wooden blade is usefull?

thanks.

[awk]

@ flux
This is very approximate, I have no experience of round magnets but basing it on 1" square ones I think you can get 16 poles on a 10" disc. From Willib's figures you will have to squeeze the coils a bit elliptical to get them in but it won't matter much.

Much depends on the prop you use and its tsr but using a reasonable wooden prop I think you have enough magnet for a decent 5ft machine.

Try your test coils with about 30 turns and I suspect you will get something like#15 in that space.


                      SIR THE COIL INFO U HAVE GIVEN IS FOR A 16 MAGNETS ON ONE ROTOR......?

[Flux]

My suggestions wre based on using a 16 pole dual rotor, that needs 32 magnets.

If you only have 24 magnets then with 10" discs you have no option but to make it 12 pole dual rotor. It will certainly work but I don't think you can meet your requirements especially with a pvc low tsr prop, you just don't have enough magnet available.

To achieve 100 Watts at 10 mph you will need in excess of 6ft prop and quite honestly it will be too slow for you to get that result with tiny alternator.

Unless you can relax the requirements for power or are prepared to invest more in the project then probably best to quit now rather than ask questiond for ages on something that is not realistically possible.

With your magnets you can make a working machine but there is a limit to the performance you can get. A few watts at 10 mph is possible even with pvc blades but by going to tiny alternators restricted by your magnet availibility and using props that I consider very limited you will not achieve the power levels you seek.

You can indeed get more from larger props but the lower speed alternators need much more magnet and copper and I personally suspect that 5ft is about the realistic limit for pvc props if you follow the common designs.

Flux

[awk]

ok
 i will stick to my 12 magnet dual rotor because i donot have budget i will make a 6 feet dia wooden blade but before this what wire gauge do i start

i make a coil of 30 turns of 26 awg wire but when i spin my rotor no reading on multimeter
then i double the windings to 60 but no result
when i shorted both the ends of wire the coil made some deflection from the rotor.

what should i do

[jimovonz]

what should i do

Change the dial to AC

[awk]

  i know that the output is in ac from stator i put multimeter on lowest AC value

[ghurd]

I must be a meter related issue.
There are volts being generated, or current would not flow when shorted, and current is flowing or the coil would not deflect.
G-

[wooferhound]

Have you built your magnet rotors yet ?
How are you testing the coil with your 24 magnets ?
What RPM are you spinning your dual rotors up to ?

[awk]

yes i have just stick 12 magnets to one rotor then make a coil

i do not know about rpm because i dont have any RPM measuring instrument ii just spin it by my hand .

i only check my coil with one rotor because i have not made a proper rotor with magnets stick to it by resin for sake of changing rotor radius may bi.
i also attached a 5mm yellow colour led at the end terminal of coil but led does not glow even once.

[Flux]

Are you sure that you have the magnets alternately N S N S round the disc. If all magnets are the same way you will get nothing.

If your multimeter is analog then try it on the lowest dc volt range and turn the disc slowly by hand. the meter will deflect forwards and backwards as each magnet passes if all is ok.

Don't try this with a digital multimeter it will show you nothing useful. I don't know what kit you have available. With 60 turns and a fairly fast spin I would expect to see some response from the led but it may take up to 3v to make it light.

Flux

[willib]

Hi awk can you post a picture of what you have so far?
That may help us to help you