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More efficient wind turbine

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While building the stator of my DIY hawt, an idea came to me to produce more energy.

I will first say a little more about the coils:
so i made the coils by using 20 cables of  gauge 24 with a length of 5,6 meters.
Per coils i have 33 turns and 9 coils in total.
When i was looking on the internet, i found that everybody used the star formation for the connection of the coils.
I was wondering why and did some research on the internet.


After a while i came across a site that gave plenty of information about 3-phase circuits. (http://www.windstuffnow.com/main/3_phase_basics)
On the site it says that:
- the star formation has at low rpms a higher voltage and a lower amperage
- the delta formation has at low rpms a lower voltage and a higher amperage
- the resistance of the delta is 1/3 of that of the star
so basically the main reason why people always use star formation is because of the higher voltage at low rpm,
but with the star formation you also lose a lot of energy at higher rpms (1/3 energy loss in comparison with delta, THAT'S A LOT)

So i was wondering if I could use the delta formation in my wind turbine and find a way to solve the low voltage problem.
After some research on the internet, i found that if you double the turns on a coil, the voltage also will multiply by 2.
So i came with an idea:
because my coils consist of 20 cables in parallel, i can divide them in 4 groups of 5 cables.
By doing this i can change the number of turns by connecting the groups with each other. (look at the cable connection diagram)
The only problem is that this will take a lot of time to make. And to automate the change of the turns you will have to set up a complex electronic control board (and I'm not good enough in electronics to do that :(  )

An other way, that is easier to make, is to switch between star and delta formation. You can use the star formation at low rpms and the delta formation at high rpms. The only problem is that I again don't know how I should automate it. I could measure the voltage and let it switch when a certain voltage is reached. The voltage an amperage in star and delta have a √3 ratio.

Is this a good idea and can someone help me with this (the automation)?

Lectric Wizard11 months ago
You might want to look into MPPT technology for your charge controller. It will "make-up the loss of voltage at low RPM, allowing your batteries to charge more efficiently. Saves all that switching gear. CHEERS!
kalefranklin11 months ago
use a centrifugal switch, like the ones in a 120VAC motor. mount that switch on your rotor, and adjust your spring tension so it will work at the correct RPM. it will also need a collector ring to transfer the switch contacts down to the ground. use this switch to operate your relay that switches from Y to Delta. its mechanical automation, and you can use a switch out of an old motor that is dead.
I made an instructable to help answer this question

http://www.instructables.com/id/Switching-from-Y-to-Delta/
PS1181 year ago
When I was in school they always called the "star" configuration a "wye". That may help in some of your web searches.

I'm a little curious why in your schematics you use rectifiers for the one and not the other. They are doing exactly the same thing, afaik.

Finally, (not knowing any different) I'd probably rig up a double pole, triple throw relay (or equivilent combination of whatever I could find) to switch each coil to/from its nearest partner to a common center.

From there, just maybe a transistor and resistor to energize that relay when it hits some given rpm/voltage.

Most of all, please write up the instructions on how to make this when you have it completed! I can't wait to see your finished design!
bmourad (author)  PS1181 year ago
yes its just as MikB said

I'm currently working on the schematics for the automation.
For the first idea it will cost a lot of money so I decided to first try the second one
who only requires tree relays (or 1 double pole, triple throw relay),a 12vdc source and a pic microcontroller (12pin)

i will certainly work my first idea out and post everything later on.
MikB PS1181 year ago
@PS118: Look at the pictures again, one uses 6 discrete diodes as a 3-ph rectifier, the other uses 2 (well, 1 and a half) standard bridge rectifiers as a 3-ph rectifier. It's all the same, really!
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