Axial Flux Wind Turbine

24 pole, 3 phase alternator. 18 coils of #20 wire 80 turns each, 6 coils in each phase connected in series, then wired 3 phases in star config. Put out lethal voltages at a very low rpm. Using N45 2" x 1" x 1/2" Neo Mags, two discs of 24 each attracting each other through coils. I need to know what the number of turns would be for #13 wire, same configuration for charging batteries.

Picture of Axial Flux Wind Turbine
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Tsiquaye1 year ago

Can I use one rotor with the two opposite sides filled with magnets and two stators with magnetic wires wind on the sides facing the rotor, please? I have not seen a wind turbine before but I want to make one by myself. I need to buy all the necessary materials outside because we do not sell any of the materials here in Ghana. Thank you.

Your idea is worth trying - another idea I have seen to save cost is have the same layout (stator coils between rotors) but magnets only on one rotor, with the other a plain steel rotor that still "pulls" the flux thru the coils.

This is awesome!

Can you provide the wiring specs for this, as well as the magnet alignment and magnet sizes? I want to build this, and would like to get as much details and instructions as I can.

Thanks so much!

glasswool3 years ago

Hello all, I have put together a 24 pole dual rotor axial flux alternator with a distributed winding, the middle phase is always producing less voltage can some one suggest why?

ISU-Joe7 years ago
I realize a lot of people already know all of this, but this is what I've learned so far while researching the subject.

Umm the power output of the generator is governed by Faraday's Law of Induction.  The current it each of the loops of wire is induced to counteract the change in the magnetic field change when the magnets are moving over it going from North to South.  The magnetic field strength drops off in strength with the cube of the distance so it's important to get the coils close to the magnets.  I'm still trying to figure out how the amperage works.  My best guess is that as long as you keep the generator turning at the same speed you can pass any amount of amperage through the thing.  So the more amps you pull the harder it is for the generator to turn at that RPM.  Of course increased amperage will result in your coils heating up, as the copper wire has a resistance that is correlated to the diameter and length.

where V=voltage, N=turns per loop, A=area (magnet or wire loop?), B=magnetic field strength in tesla

where B=magnetic strength, u=permeability constant, d = distance from center of dipole (center of magnet), U=magnetic moment

Also it's important how you wire your coils.  Of course with the 3 phase setup you are able to put the 3 phases which are 30 degrees out of phase of each other through a rectifier and produce a steady DC current; as the summation of the three waves results in a line.  So assuming you have 9 coils you can have 3 sets either in parallel or in a series.  If you put them in a series you can produce hire voltage at lower RPMS.  Although apparently putting them parallel has benefits at higher RPMS.


I'm thinking of trying to make my generator with 2 stators and 3 rotors.  Thus allowing the average distance each of the coils to be closer to the magnets.  I still have not run the calculations to see what benefit this would product.  I'm hoping to lower the number of coils needed.  I'm trying for 24 volts at 300 RPM, well actaully I would want what 28 volts so I could then charge two 12 volt batteries in series.   Apparently due to lenz's law you need 14 volts to charge a 12 volt battery.  I haven't had the chance to look into this.

Oh I had another thought.  If all the magnets had their poles facing the same direction rather than alternating (alternating current) the generator would produce direct current rather than alternating.  However, this would surely reduce the power output.

I hope it's not too late to comment.
I ran an excel to calculate what can be expected from a 3phase PMA.
Since I cannot attach a file here is the sheet.

The basic formula I used is: V=#phase*n*A*B/t
I will be happy to hear comments, and also send the excel if someone wants to review it

number of poles 24
magnet placement angle (degrees) 15
#Phase PHASE 3
n coils per phase 6
n per coil 21
N per phase 126
A cm^2 11
A A m^2 0.0011
B (Gauss) 13200
B B (Tesla) 1.32
RPM (for 2*pi rotation) 120
time to rotate 15 degrees (sec) 0.020833333
"since the coil enters the N pole and S pole simultaneously
we probably need to consider the time it takes to rotate 7.5 degrees"
t time to rotate 7.5 degrees (sec) 0.010416667
V V per phase 17.563392
V star 52.690176
V delta 17.563392

resistivity Ohm-cm 0.00000167
wire cross section cm^2 0.01227
single loop length cm 14.4
single coil resistance Ohm 0.041157946
jetboy7 years ago
how many turns to produce 12+ v with 14 gauge wire (9 coils) thanks
How many turns would I need with a #22 gauge wire for 12volt application?
Great 'ible :)
nolte9198 years ago
Hey what's that middle picture of? The tall cylinder looking thing?
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