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Wind Generator PMA

Discussion in 'Renewable Energy' started by GatorGnet, Oct 25, 2010.

  1. GatorGnet

    GatorGnet New Member

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    I had a couple questions on wind generators. I see that most people build or use AC alternators instead of DC generators. Is there a benefit to using AC then rectifying it to DC?

    Second:
    Going with an AC axial flux alternator. Does magnet strength effect the output a great deal? I see a lot of designs using roughly 20# pull neo magnets. If you built it with 100+# pull magnets, would it greatly increase the output?

    Going back to the first question, could you just make a DC generator using the axial design(making one large coil instead of the multi AC coil way)?
     
  2. bryan1

    bryan1 Well-Known Member

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    Hi Gator,
    Ever hear of a DC wind genny outputting 4kw's at 260 rpm or even one outputting 1 kw. Using magnets going past a coil of wire will produce AC and most homebrew design stick to the 4:3 rule. The general arrangement is 12 magnets on each disk and 9 coils wired 3 each in series around the stator to produce 3 phase output. When a AC wind generator is connected to a batterybank the voltage is clamped by the batteries and the current will rise. Some radial flux generators have a heap of magnets and some homebrew designs have been proven winners. But the complexity in building them outways the simplicity of building a dual axial flux.

    Regards Bryan
     
  3. GatorGnet

    GatorGnet New Member

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    That is why I asked. Everything I have found uses AC and I do not have any issue using it. Just learning the whys and why nots.

    Does the strength of the magnets effect the output?
     
  4. dave

    Dave New Member

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  5. bryan1

    bryan1 Well-Known Member

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    It sure does, try and make a 3kw dual axial flux wind generator using ferrites...... when the neo magnets came along the homebrew turbines had the best thing since sliced bread to play with. with my first dual Axial flux genny I'm using 50mm diameter by 15mm thick and N52 grade, that should produce around 4kw's at 24 volts on a windy day. That will have my batterybank fully charged and the hot water tank as the dumpload near boiling away....

    Cheers Bryan
     
  6. GatorGnet

    GatorGnet New Member

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    I have been looking at the different size and grades of neo magnets and I am still deciding on which to use. There are some 2" ones that are rated at 200lbs of pull! I can only imagine what kind of pull the two rotors would have with each other with those!
     
  7. Simple Simon

    Simple Simon New Member

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    Hi Gator

    The word alternator means Ac curent. When you pass Mags over a coil, you generate A.C. power.

    You can use the ac power as it is... But the Hertz / cycles will be all over the place as the wind goes up and down.

    So we Rectifie the ac to Dc "Direct Curent" Then we can store it in batteries. to be used when we need it. Most inverters require Dc volts to work.

    The bigger the Mags, the more power you can produce.

    pounds of pull is not the way the mags are graded. They will have to be matched to the coils. so you will have to select the voltage you want. 12 / 24 /36/ 48 or what ever you want.

    Read up on 3 phase. They make the best stators.

    S. Simon
     
    Last edited: Oct 28, 2010
  8. GatorGnet

    GatorGnet New Member

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    I understand the reasoning behind using two magnet rotors with one stator with the opposite polls aligned to produce better power but what would you get if you use two stators one on each side of a single rotor? S|R|S

    I understand more then I may lead on too just trying to learn more whys and hows and what ifs.

    Also, can you put multiple mags in groups to form larger area mags. This is a really crude drawing and is not to scale or correct number of mags. I just wanted to get the point accross.

    As always, thank you. This form is the best thing for wanna be's like mu'ah.

    [​IMG]
     
    Last edited: Nov 1, 2010
  9. Simple Simon

    Simple Simon New Member

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    Hi Gator
    Yes... you can add more mags. And you can also stack them too. The more mag you have passing over a coil,
    The more out put it will produce.

    But keeping them on the mag plate then becomes a problem. Best is to use "big" single mags with holes to bolt them on.
    If you are using round mags then lay them out in a triangle shape. the inside of the triangle shape coil would be just slightly larger than the mag lay out.

    S. Simon
     
  10. GatorGnet

    GatorGnet New Member

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    Which is more important to output, number of mags or number of coils?
     
  11. GatorGnet

    GatorGnet New Member

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    I was thinking about laying out the mags and casting them in resin like the stator. Any thoughts?
     
  12. Simple Simon

    Simple Simon New Member

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    Gator

    Both are important. The Mags make the power, The coils collect it. The 3 phase consontrats it.

    It's the layout that really makes things work better. "Starting with a 3 phase stator" 9 coils>> Wired in 3 phase.
    12 Mags. pasing over the coils. Like 1 1/4 mags at a time. that captures the most current possable.
    Other 4 to 3 number combos can also be used. "I have not done so. but it can be done. I have found that this type works for me. Rember you can also make a "Dual" stator. That will give you another 50 + %. in Amps. 12 volts + 50 amps= 600 Watts. Nice start there.

    Resin will help. But how long will it hold... Use some heavy nylon 6 to 10 mm / 1/4 to 3/8" thick ( the size of the Mag plate) and set the mags into the cut out holes the shape / size of the Mags you will be using. Do a google search of "3 phase rotors", There are many posts of what other have done. Admin Bryin1 has some links on the site that are excellent. Reseach them too. and if you build, Be sure to follow the info exaculy as you will want one that is a proven preformer.
    For you own.

    S. Simon
     
  13. GatorGnet

    GatorGnet New Member

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    I will look into the nylon. I was thinking of a steel plate with the mags then cast in resin keeping the mags close to the surface. Just an idea though. Does the duel mag rotor setups make a great deal more power or can you use a single rotor and still get "ok" power?
     
  14. Simple Simon

    Simple Simon New Member

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    Hi Gator

    It all Starts with the Magnets. The more powerfull they are. The more current you will get back. You Then wind your first coil to match your Mags "and" your intended voltage.

    The Rotor will made from a mild steel about 1/2" / 12.5mm thick.

    Do not try to use Stainless steel, Alumium, or wood.. They will not give you any Flux return. and will give you little to no power.

    The problem with steel is the rusting issue. so glueing the mags are a problem. That is why I like to get mags with a hole in them, and use a "STAINLESS" Bolt through them. A Stainless bolt in the Mag does not change the flux pattern.

    With the right mags and coils, in 3 phase you should be able to build a single Stator and still get 800 watts.

    S. Simon
     
  15. itsandbits1

    itsandbits1 New Member

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    bc. ca.
    a dual rotor setup will almost double the power output of a single if the same mags are on them both
     
  16. Simple Simon

    Simple Simon New Member

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    Almost

    Hi itsandbits

    I like to say plus, Because to many times a corner gets cut. cheaper mags, a Bit differant wire, heavier or lighter wire. We all love to save money. So we cut corners.

    And if you get more than thats a "PLUS". In theroy you will double. Less you losses. They are the ones that realy count.

    S. Simon
     

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