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Forum Index : Windmills : like to build a axial flux, but no volts
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| windtinker Newbie  Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Hi I've been experimenting with coils and magnetic to build a wind turbine, but the highest voltages I got from a 300turn coil was 0.02volts(dc and ac on multimeter), using 12mm square Neo and 10cm ferrite and 100 turn electromagnetic. I would like to try the designs of Hughs but don't have the money to waste on anything less than 12 volt. What would I bee doing wrong. |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Windtinker Can you post some photos as to your method of obtaining the readings you get. If you are trying to reinvent the wheel you may well waste time and money, there are many designs out there working and using standard bits to base on. You live in the homeland of the F&P motor that has a good track record as a starter project and a junk yard scrounge usually will turn up an old wash machine for next to nothing, All the best Bob Foolin Around |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Going to need a lot more info windtinker, or a photo? The coil will make AC, dont measure on DC range. How quickly is the magnet moving past the coil? What is the coil shape? Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Wraping wire around a steel pipe and other designs(2kg of 1mm :( ). I was moving the magtnic by hand back and forth, but the mutlimeter doesn't get below .0 AC. Thought about using a induction motor(maybe some tweaking), I think a fan runs on them but will see about the washing machines I'll look throught the site at the f&p threads and have a readup. 60rpm for 12 volt would be good or two in series. |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
I've started build a turbine. I ordered some Neo Mags(30*10mm) and made one of the rotors, trying a test coil of 60 turns moving it by hand over the rotor,i'm geting 0.02 volt dc with a diode inline. Would this be right? 
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi windtinker Ditch the diode and measure it in AC volts. Also, waving a coil by hand isn't going to tell you anything usefull, too many unknowns. To get an usefull figure, you need to know the height of the coil over the magnet, and the speed. What we normally do is make the magnet plates, and assemble them on a test stand so they can spin freely, then use a test coil to see how many volts we are generating at a certain spacing between the magnet plates, and a certain RPM. From there we can work out the best magnet plate spacing, and the number of turns, wire thickness, etc to use for our coils. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Done some testing, @355 Rpm 0.7 v * 60 Turns no core 1.5 v * 60 Turns Iron core 3.2 v * 130 Turns Iron core @937 Rpm 1.2 v * 60 turns no core The thing isn't balanced there good and at 937 it was shacking like hell :) I will probable go for 200 turns , 3 coils in series , with both in parallel. |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Built part of the rotor. Was thinking about putting 8 60*40*10 ferrite mags on there, with a iron cored coil. I've got 10 neo mags 30*10, should I get 6 more and use neos or go the ferrite way. I'm thinking off building more and a second one with neos would probable be to much? 
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| electrondady1 Senior Member  Joined: 12/02/2009 Location: CanadaPosts: 208 |
you can weld tinker and that will come in handy later. you need to mount your magnets on a metal disk that can rotate at a controllable rpm. the thickness of that metal disk is directly related to the strength of your magnets. a good start is 10" saw blades. when the mags are mounted you can do a test coil. mind your fingers ! |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Attaching the magnets to that square hollow section would loose most of their power. The above messages mentions a disk, just in case you are perplexed why so  consider the magnetic flux lines behaving in steel like electric current does in copper wire.
You want to aim for the shortest return path for the magnetic flux (least resistance), it *has* to flow from #1 magnet's pole N face to the #2 magnet's S pole and then back from the #2 N pole to the #1 S pole, completing the circuit. This should be the shortest path possible with plenty of iron to conduct the flux. Iron cored coils can cause severe cogging unless you take suitable precautions - there are messages on this subject on this forum. Build the coils as thin as practical to limit the flux path through them, especially important if you use air cores & neo magnets. If it was me I'd consider your nice welding as a practice job, do some more reading on axial flux alternator design - plenty of ideas have been posted here so why re- invent the wheel? Klaus |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Done abit more of the build. I've got a test coil on there 50 turns, spinning it by hand gives 0.1 volt with one set of neos. Going to do some more test, i'm aiming for 1.5 volt, spinning at 10rev/sec(120volts). I see what people mean about the clogging, it takes abit of force to start it spinning plus gearing. @electrondady1,Tinker I haven't added the steel disk behind because I would have to done what I did and cut a hole at the top, but now thinking about getting a skill saw blade and testing the improvement. Thanks 
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
OK I can see how this is going to work now. I think the results are going to be dissapointing. There's a couple of things that are going to kill the performance. First up, your going to have a lot of "cogging", where the magents and poles try to line up and make it hard to spin the thing from a stand still. Secondly, it looks like your using solid steel rods for your core centers. The problem with solid steel cores is they suffer from eddy currents, and dont like to change flux direction. What this means is a lot of the magnets flux is wasted, and is why motors/generators use laminated cores instead of solid cores. I would put this down to a learning exercise. By all means finish it, but dont invest too much time and money into it. If you use your same magnets and build a tried and tested design like the standard axial flux alternator, then you could expect many times the output power that could be achieved with this build your working on now. Its all part of the learning process, been there, done that. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Gizmo The result were shocking. :) I'm not sure weather 8 poles is enough. After I try a f&p build might go back and stick two flat plates on and try for 16+ poles. |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Just a update. The softsteel for the cores as about 131% loss for each doubling of poles, and the ac voltage swing like mad. With transformer steel(microwave) the ac is stable and voltage pretty much doubles with poles. At 2rev/sec and 6*24mm softsteel core 2 Poles 10T 0.005V 20T 0.026V 30T 0.044V 40T 0.069V 50T 0.096V 60T 0.112V 4 Poles 10T 0.015V 20T 0.045V 30T 0.070V 40T 0.100V 50T 0.130V 60T 0.160V 130T soft steelcore 1P 0.090V 2P 0.106V 4P 0.187V 8P 0.310V 16P 0.472V assumed 24P 0.596V assumed 130T transformer steel 1P 0.080V 2P 0.120V 4P 0.220V 8P 0.400V 16P 0.800V assumed 24P 1.200V assumed I've add a rim on the face of the rotor, cheap than plate :), and should have some figures in a couple of days if its improved it. |
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| windtinker Newbie Joined: 16/01/2012 Location: New ZealandPosts: 38 |
Hi flogging a dead thread, but this was the final prototype design with 12 mags 100*20*8mm 180turns per coil it should get upto about 12volt by turning by hand. 
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