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My boy wants to make a wind generator and we have a 3D printer.

We have decided to go with an axial flux style 140mm diameter with 12 iron free coils (4 per phase) so it can turn easily. Without gears, we get can get 500RPM but normally maximum of 300RPM. We have done 300 turns per coil using 0.35 wire. We have eight 30mm round x 5mm neodymium magnets.

What would be best to do to increase power as we are not getting a lot?

  1. Change wire size
  2. Use twelve 40x10mmx5mm bar magnets
  3. More turns (but not much room for more)
  4. We used triangle coils. Would round ones be better?

I am not an engineer just trying to remember from college and please my boy. Any advice would be a great help if more than one please put them in priority.

Update:

enter image description here

This is the design we have. We get 12 volts but only 270mA.

If we use 12 x 30mm bar magnets they would line up with the flux lines better so maybe that's where we failed the most.

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    \$\begingroup\$ Without being able to see what you're doing it's hard to say. Can you edit your question with some pictures (you can drag & drop pictures into the question), and be sure to include dimensions. \$\endgroup\$
    – TimWescott
    Commented Jul 9, 2022 at 23:17
  • \$\begingroup\$ Craig, when worried about not getting a lot from your efforts, the very first thing I'd do is work through the required theories involved in making predictions. (Or buy a professional product I could use to calibrate results.) Only then can you know if you are getting close, or not, to what can be done. Otherwise, you just can't know. Ungeared, when you are getting 300 RPM what is the wind speed at that time? What's the blade diameter into the wind? Do you have a specific pitch? Or is it variable? Have you looked at the old NACA (pre-NASA) tables for wind blades? \$\endgroup\$
    – jonk
    Commented Jul 9, 2022 at 23:50
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    \$\begingroup\$ Can you show the magnetic flux path? Most improvements are hidden there \$\endgroup\$
    – Jens
    Commented Jul 10, 2022 at 0:42
  • \$\begingroup\$ Quality of magnets. Coil size relative to magnets. More turns. Finer wire. So many things can be poorly done. Bigger wind mill. Put your boy on the roof (maybe not the best idea). Pictures with dimensions will help. \$\endgroup\$
    – StainlessSteelRat
    Commented Jul 10, 2022 at 0:45
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    \$\begingroup\$ "We get 12 volts but only 270mA." I think that's pretty good from the results I've seen from other home setups. \$\endgroup\$
    – DKNguyen
    Commented Jul 11, 2022 at 13:33

2 Answers 2

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1. Get an MPPT

Probably impractical for a school project, but will provide a big increase.

2. Put the stator and rotor closer together.

Even a tiny bit closer will make a difference.

3. Change the blades.

It is important to get the right blades for your conditions (windspeed).

4. Add a second stator to the other side of your magnets.

Double the magnetic flux that you are taking advantage of.

5. Better magnets

Since its a school project, this extra cost may not be worth it to you.

Here's a good paper you can reference: https://we.riseup.net/assets/233731/Axial+Flux+Permanent+Magnet+Generator+Design.pdf

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You mention that you have a 3d printer, just wondering, as you don't mention the rotor, if you're using a printed plastic rotor for the magnets rather than an iron one? this would dramatically reduce the efficiency....just a thought. Also looking at the diagram, 12 bar magnets 30mm long would seem to fit better than 40mm ones, and would be cheaper too

Good luck with the project, I'm doing something very similar but making a VAWT just to supplement solar ( no direct sun from Nov-Mar ) charging at a very low level to a 69Ah battery

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