Axial Flux generator - Low RPM - "High" voltage

[404notfound]

Hi everyone, I learned this forum exists with Marco Reps YT channel.

Anyway, I'm starting to need your help for my project.

I started to build a single phase axial flow, low speed (10hz ish), high voltage (5v ish) for my wind tubrine (500mm diameter, with variable pitch ).

My first prototype works ok (ish), but when I plug an oscilloscope to the coil, I do not get a perfect and beautiful sine wave.

 IMG_0404.JPEG (103.66 kB. 444x386 - viewed 250 times.)


I thought I was doing ok, but heh.

Any idea?

[moffy]

Getting a good sine wave out of an generator requires careful design and experience, especially for the magnetic field. It's almost as much art(experience) as science, and even if you get your nice sine when unloaded, loading currents will distort the waveform unless compensated for. It is a non trivial topic to master.

[404notfound]

Ok so I got better waveform with an old classic inner rotor PM generator.

My issue seems to came from my geometry !

Any ideas?

[PCB.Wiz]

My first prototype works ok (ish), but when I plug an oscilloscope to the coil, I do not get a perfect and beautiful sine wave.

Why do you need 'a perfect and beautiful sine wave' ?
If this for pickup sensor, or is this the main energy extracting generator ?
Mostly for wind generators, designers use a multi pole 'washing machine' type motor, and then work the electronics to suit their speed/load point.

[moffy]

Is the stator some sort of laminated steel or is it what it looks like, some sort of plastic 3D print? Read some books on magnetic circuits, transformer design and motor design if you want to understand what you are doing, it is a non trivial topic.

[amyk]

Read some books on magnetic circuits, transformer design and motor design if you want to understand what you are doing, it is a non trivial topic.

In particular I recommend the old books from the turn of the century, in the era before semiconductors and when getting a good sinusoidal output was more important than it is now.

[jonpaul]

saturation of the iron

[404notfound]

Thank you all for your replies.

Yes, for the moment, the protypes are 3D printed with standard PLA. For the future, I'm thinking of using this: https://www.amolen.com/products/amolen-metal-iron-pla-filament-1kg1-75

All the coils are made with about 800 turns of 0.4mm wire.

Magnets are N52.

The first design, Axial Flux PM was single-phase (6 poles, 3 coils).
The second, inner Rotor PM, was 3 phase (8 poles, 6 coils, Delta config, ABCABC).

I try to stay under 100mm diameter for the stator/Rotor.

[moffy]

To get a good voltage out of a generator you need to couple as much of the magnetic field as possible through the coil, therefore you need a low impedance magnetic path, preferably of insulated laminated steel. A 3D print will have lots of air gaps because of the filler material even if it has a magnetic material within. If I could use a food analogy, you are looking for a fast food response to something that is cordon bleu in  complexity, one needs to go to school and study first.

[404notfound]

U kow what ?

I wont go to school and i will make it worked.

[moffy]

U kow what ?

I wont go to school and i will make it worked.

Bon chance, it's not a matter of making it work, even what you have done, kinda works, it's a matter of whether it works well.

[404notfound]

Exactly, and this is why I ask my question about deformed sine wave in the first place, but no one seems to have any ideas.

Anyway, I'm making an outrunner PM in a 9N8P Delta config (AaABbBCcC) (+/- a dLRK config).

Stay Tuned !

[Simon]

So how much power does this little generator make?

[404notfound]

At the moment, my biggest problem is voltage, not power. I'm getting up to 2VPP with 200trmin-1 (open circuit) with a single coil

The latest design is in print, more inofs during the day.