Piggott Windturbine and charging regulation issues [Done]

[sperate]

Hello to all of you interested in wind turbines and analogics.

Back after three months with a prototype board tested in lab conditions and fully working !!
Next step is to test it with the wind turbine.

Schematic and board will be posted very soon on the website and here on the forum.

See you.

[sperate]

Here are the files and a detailed photo of the set-up.

Tested with the turbine and a little wind, works great !!


Feel free to ask me questions.

[Ichan]

Would like to hear the description of "fully working"..

The controller only sense battery voltage?

-ichan

[sperate]

The controller only sense battery voltage?

That's right.

I've abandoned current sensing since the differential amplifier I tried to make was not precise enough.
In fact, the problem wasn't the amplifier but the voltage divider on each input. In integrated high side current sensing circuits, Maxim uses laser cut resistors to achieve sufficient precision at the input of the differential amplifier.
Anyway I could add it later, but I think I will rather try to sense the current at ground level. I just have to figure out how to do it without interfering on the voltage sense ..

[Ichan]

For low side current sensing with the shunt resistor on the bottom leg of the battery, the battery voltage value need to be subtracted by voltage across the shunt resistor.

How is the wind turbine itself going?

-ichan

[sperate]

The turbine itself is going well, still turning, yawing, furling after the snow, rain and summer sun, but I think, now that I've started to make it work, that I has a power problem.

I think that the rotational speed of the turbine, when it starts to inject current in the battery/controller isn't high enough. Thus, it can not catch enough power in the incoming wind because the battery voltage clamps the rotational speed. I've asked Tripalium about that and I'm awaiting answer from them.
A solution would be to move apart the magnets disks from the stator, allowing higher rpm for the same output voltage ..

We'll see.

sperate.

[solutions]

You should be able to pull enough current to brake the mill so it never hits the battery voltage speed.

IMO, your current controller may be the problem - assuming the impedance of the motor windings is low enough to supply high current.

[sperate]

Theoretically the motor is able to provide 700W at 10m/s windspeed.
At that moment, I've managed to have 10 amps incoming current (in both the battery and the diversion load) on 28.8V regulated voltage, which means about 290W.
It's interesting, but I've seen these 10 amps only for brief moments.
Maybe it's just the fact that there is not enough wind .. but it seemed to me that the wind was pretty strong that time and if I'm awaiting storms to have those 700W it will become less interesting.

The only way to be sure about what is happening is to measure the wind speed in correlation with the rpm of the turbine and to calculate in strong winds, leading to my famous 10 amps, what is the TSR (tip speed ratio) of the turbine. If the measured TSR is far from the design TSR of the blades (which in my case is 7) then the problem is due to the clamping effect of the batteries/controller.

I think I have to let the turbine turn faster if I want the 700W. But even without the controller, the battery won't let it. This is because of the cut in speed (the rpm at which the motor voltage exceeds the battery voltage and starts to inject current in it) which in my case I think is too low.

sperate.

-------- Edit ---------
TSR = Blade tip speed / Incoming wind speed

[solutions]

Yes, make it turn faster
 

http://www.youtube.com/watch?v=CqEccgR0q-o

[Ichan]

How about testing the turbine with dummy load? An array of halogen lamps perhaps..

-ichan

[sperate]

Hello,

after a little while, i've ended working on the charging regulator and had time to update my webpage on this subject.

http://sperate.free.fr/eolienne_elec.html

Downloadable files of the project are at the bottom of the page.

Cheers.