One Man's Adventures into Renewal Energy

Solar Panel

Night - 0 Watts

Battery Bank

Very Low - 11.87 Volts
Battery and Panel Stats Updated @ 21/02/2017 16:27
Please help me to continue hosting this website & associated costs by donating £2.
In return, I'll email you a ZIP file containing arduino code + all images from the website + some extra ones that aren't on the website...all in high res (370MB of pics!).

DIY Horizontal HAWT Wind Turbine / Generator MKIII

15th September 2015

Now that winter is on its way and the wind is picking up, I've decided to start looking at wind power again.

The Wind Turbines I've built are OK and do work, but they have issues -

So to address these issues, I'm going to create a brand new generator, building the motor from scratch, and using RC plane props for the blades.





Here is the end result - Basically, it's a Radial Air Core Generator/Alternator. The key feature of an air core alternator is that they are ironless. Because they are ironless, the magnet doesn't get attracted to anything during its rotation, which completely eliminates the cogging effect, which means the generator will turn with very little force applied.
Read below for how I constructed it -
DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator



DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
Here is brief overview of parts needed -
Magnet - This is the most important part of the build. The magnet I purchased is diametrically magnetised, which is very important.
The magnet is 20mm in diameter. This is important as this will dictate a lot of the build process. The larger the diameter of the magnet, the more magnetic influence (gauss) the magnet will have, which in turn means you can increase the number of turns you can do on the coil...and the more turns, the more volts you'll get out of it.
The magnet was fairly expensive at £14.



DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
As the generator works best when everything around the magnet is ironless, I bought some nylon nuts & bolts to hold everything together.



DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
Using 4mm polycarbonate, you need to construct 2 x end pieces.
The only things you need to be get right is the diameter of the centre circle - this needs to be 3-4mm more than the diameter of your magnet, in order to leave sufficient gap so your windings don't rub against the magnet. You could drop this 3-4mm even lower if you're feeling daring...as the closer your windings are to the magnet, the better.

The other consideration is the two long vertical uprights. They need to be twice the width of the nylon bolts you bought.

Yes - it does look like a Tie-Fighter!



DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
Bolt it all together!
You can see that I didn't use the nylon bolts, instead I went for some zinc ones I had lying around as they were longer.
I stuck with using the nylon nuts and washers.
I used a couple of nuts to secure the magnet on the shaft.
Everything except the inner shaft is ironless.
You should end up with the shaft spinning freely with no feeling of 'cogging'.




DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
Top down view.



DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
Front view.



DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
This is the boring part! You now need to wind the thing.

I used 0.2mm enamelled copper wire. You can go thicker which will allow more amps handling capabilities, but I don't expect I'll be anywhere near the kind of current levels that might stress the wire. The compromise is volts versus amp rating. The thicker the wire, the less turns you can accommodate, which means less volts outputted.

You need to wind each side in a clockwise formation. So wind one side clockwise. Rotate it 180° and wind again in a clockwise direction.
Make sure you leave plenty of trailing wire on the 4 ends you'll end up with.

I also learnt the hard way about ensuring the shaft remains freely spinning as you wind the turns. As you wind the turns you will compress the two end pieces together, making them rub against the nuts holding the magnet in place. I ended up winding about 300 turns before realising I'd clamped the shaft! I had to strip the 300 turns and start again.
The best way to avoid this is to put a small wedge in between the plastic end pieces and the nuts - something you can later extract after winding - a match stick will do.
And also periodically check all it's free spinning as you wind.




DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
Apologies for the crude drawing, this is simply to give you an idea on how to wire up.





DIY Horizontal HAWT Wind Turbine Shaft Radial Air Core Alternator
And this is the end result.
The actual vane I created out of 4mm polycarbonate. You're free to design this however you like.

I glued the wound air core generator onto the polycarbonate using epoxy.

The yaw bearing is made using some bits I had lying around - namely a hollow bit of rod I had, which happened to fit snugly in a plastic housing. Applied a bit of grease and it rotates very freely.

The actual propeller is a 13" slow fly prop (13" diameter x 6.5" pitch). This was pretty cheap at only £3.
I believe there is a lot of scope for improvement with the prop.
Obviously, a bigger prop is always better - I reckon I could go up to 15" in my garden.
Also, a 3 blade prop will almost definitely outperform this 2 blade prop.
I've also been doing some reading on pitch angles - apparently a lower pitch is better for wind turbines. 30° is supposedly the optimal pitch degrees, but I've been unable to do the maths to convert this to pitch angle in inches.
I plan on buying a few more blades until I find the best one. I'll keep you updated on my findings.

I wound a total of 1200 turns on this generator (600 on each side).
Spinning the generator with a cordless drill outputs 6 volts AC. I don't really know the RPMs of the drill, so it's difficult to make an educated guess on likely output in the wind, but I am convinced I'm gonna have to add more turns to the windings to get the 14 volts I need for battery charging.
MKIV Turbine will be wound with 2500 turns when I get it completed!






Comments

Claire (local lesbian) - 12/01/2017 11:15:28
I have some quite frequent wind power of my own that I think you could utilise. Email me to discuss. By the way, it looks like a four year old drew that picture.

Name

Email Address (won't be shown)

Human Check - What colour is the sky?

Comment











Copyright 2017 BinaryOrbit.org