Hobbiyst DIY generator - same number of wire coil turns terribly important...?

Thread Starter

harleydk

Joined Aug 14, 2022
10
I would like to try my hand a constructing a tiny 3-phase axial flux generator. Basically I'm just wanting to replicate some of those clever people on YouTube and see if I can generate power from wind to light a few LEDs in my garden, there's nothing more to it. However, I haven't been able to search my way around this question: how important is it - given the hobbyist scope of the project - to have the exact same number of turns for the generator wire coils? I'm wanting to dive in and start turning the coils by hand, but will I render the thing unbalanced and useless if some of the coils are 10-15 turns less than some of the others?

Many thanks in advance.
 

cmartinez

Joined Jan 17, 2007
7,762
The number of coils, coil diameter and wire gauge is very important. However, if you're winding coils with a 100 turns or more, an extra or missed couple of turns won't be much of a difference. Especially if it's for amateur purposes.

Do you already have a plan or design that you'd like to execute?

Also, you may want to take a look at this thread.
 
Last edited:

MisterBill2

Joined Jan 23, 2018
12,678
The number of turns should attempt to be close, if not there will be a slight voltage ripple in the outout voltage Possibly enough voltage ripple to measure.
 

Thread Starter

harleydk

Joined Aug 14, 2022
10
However, if you're winding coils with a 100 turns or more, an extra or missed couple of turns won't be much of a difference. Especially if it's for amateur purposes.
Thank you for your kind reply, that - for my amateur purpose, as you state - offers me relief that I can keep the count in my head and roll away.

Also the link you provided is very inspirational, and I thank you for that also. Have a great day.
 

MisterBill2

Joined Jan 23, 2018
12,678
Lighting LEDs in a garden is not an application demanding tight regulation of the voltage. And it sounds like an interesting project to create an axial flux generator, especially a three phase one.
Please let us know how it works out.
 

Thread Starter

harleydk

Joined Aug 14, 2022
10
Hello,

Nice! ... say, how did you come up with the 700 number?
I won't hesitate to confess I did not calculate it - I stole it from those in the better know. This here fellow has already magnificiently done what I aim to replicate - https://www.thingiverse.com/thing:633603/comments

I did find a lot of tremendously valuable information on all the basics of axial generators here, perhaps useful also for others: https://www.heliciel.com/en/Library/generateur eoilenne flux axial.pdf

The generosity of some people never seizes to amaze me. If I hadn't in my time put up a lot of free material myself I would've by now felt tremendous guilt, I suspect.
 

MisterBill2

Joined Jan 23, 2018
12,678
interesting indeed. Just consider what the generator could do if those coils had cores of a material more permeable than air. and smaller air gaps in the magnetic flux paths.
 

Thread Starter

harleydk

Joined Aug 14, 2022
10
interesting indeed. Just consider what the generator could do if those coils had cores of a material more permeable than air. and smaller air gaps in the magnetic flux paths.
Indeed is the word. Trade-offs, always trade-offs. Air core makes at least for an impact given the lightest of breezes. I've designed the coils such that I can - they're on 3d-printed 'shells' - experiment with some sort of core. I.e. nails of various sizes...
 

MisterBill2

Joined Jan 23, 2018
12,678
There is a large body of information available about improving the efficiency and performance of motors and generators, and a fair amount is freely available. I suggest reading about how to improve the efficiency, some small changes can produce large benefits. More power from less copper, in short.
 

Thread Starter

harleydk

Joined Aug 14, 2022
10
I suggest reading about how to improve the efficiency, some small changes can produce large benefits. More power from less copper, in short.
True, and I do look forward to reading up and experimenting to improve the efficiency. At present I won't concern myself too much with it - I merely desire to indulge in the carefree act of creation. Beyond a hopefully adequate prototype I will no doubt, as I do with all my coding endeavors, revisit and refine.
 

MisterBill2

Joined Jan 23, 2018
12,678
I find that both experimenting and creating are far more rewarding and enjoyable when I understand what I am doing instead of blindly failing away at some challenge. Of course, when experimenting I generally have some results I hope to achieve.
With a generator, getting more output for the same effort would be my goal.
 

KeithWalker

Joined Jul 10, 2017
2,453
If you plan on experimenting with magnetic cores to the coils, soft iron has less magnetic hysteresis than tempered iron. If you use nails or iron wire, heat them cherry red and let it cool slowly to soften the metal. It will make a noticeable difference.
 

Thread Starter

harleydk

Joined Aug 14, 2022
10
Please let us know how it works out.
Well it's done to the best of my satisfaction now, enclosed pictures demonstrates the working prototype. I get 12v from it, haven't measured the current but it's undoubtedly enough for my meagre garden-light requirements. I have no guess about the AWG-rating of the wire, I just pulled it from a coil I found inside a discarded microwave-oven I came across.

What works well:

- The 3d-printed mounting that holds it all together, it feels like a sturdy design.
- The magnets are held firmly in place by the way I designed the rotor (https://www.tinkercad.com/things/6l8Wafbcfa4). So no messy gluing.
- The coils are mounted on a holder which 'click' into place into the stator, after winding. I originally wanted to go coreless, but as I yanked all the bearings from a pair of discarded roller-blades I discovered they were set in small flanges I then utilized as the core to my coils. Given the 'click-design' I could easily retrospectively mount an iron black-plate to the stator by way of the holes. Or perhaps even just mount iron washers to the individual cores.


What doesn't work well:

- The 3d-printed rotor is skewed, warped on account of the inaccuracies of my sad 3d-printer. Wish I had better ways of machining these parts. I deliberately designed them flat, so as to be machined or laser-cut; maybe one day I'll gain access to better tools. Generally I'm confident I would get much, much better results with better machined parts.
- The wiring behind the stator I had wanted to go into tunnels I'd designed into the stator body, but that didn't really work out. Perhaps with thicker wire they would conform to my wishes.
- I failed to design a model where I could have a rotor on both sides of the stator, which is otherwise designed (flat) to accommodate one such.

All in all it's been a fun exercise, and of course happy to see it works the way I intended it to work.

Thank you for all your considerations in regards to the project.
 

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