Low RPM wind power generator

[ArNvC]

Hello all,
I'm trying to set up a wind driven small generator. However, the wind speed is less at times and is about 250-300 rpm at an average. Even a small, seemingly fast windmill might do most of its work at 600 rpm, not nearly fast enough for a car or truck alternator. This means that gearing up with pulleys or other methods is needed, so lots of power is lost to friction.

Designing a machine for low rpm is costly. Can you people give me some other ideas regarding this...I intend to make it a direct-drive generator fractional Kwatt o/p.

 

[tpetar]

Did you use Neodymium magnet for magnetic field?

What diameter of alternator and how many poles you have?



Standard car alternator is not suitable for this job, alternator rotor need to be with permanent magnets. This conversion can be done.

 

[BradtheRad]

I wonder why the farm-style windmill is not used more to power generators? It has many wide vanes, compared to the typical wind turbine with just a few narrow blades.

You would think many wide vanes will catch the wind better.

This means that gearing up with pulleys or other methods is needed, so lots of power is lost to friction.

Even if you can minimize friction, an electrical load will slow down the windmill. The more current you draw from it, the harder it is to turn.

 

[tpetar]

Because of that permanent magnet is need as source of magnetic field. But in this case voltage regulation is needed, because voltage will raise under higher RPM. With this alternator can produce power on lower speeds, and there is no resistance under load.

 

[chuckey]

the construction of amateur wind turbines are all over the WEB, use Google to find them. they typically use a steel disc with lots (12/24) small magnets epoxied to them, this lot rotates. Facing this spinning disc, there are a 6-12 coils of thick wire (without iron cores) the windings are put in series. these sort of machines can produce up to 1kW with 3 narrow turbine blades 3m long.
the most efficient turbine blade is one with a single blade but is difficult to actual make work, two is still difficult to make work as the lower blade is interefered with by the actual pylon. Three suffers less interference from the pylon. With multi bladed fans each blade run in the wake of the next blade making them inefficient.
Frank

 

[ArNvC]

Thanks for all your help...

Did you use Neodymium magnet for magnetic field?

No, but I was thinking of a cheaper alternative to Nd magnets.
I was wondering to make use of a single phase or maybe a three phase induction generator instead of a car altern. with more number of poles in it preferably 8 or 10 poles which would bring down the synchronous speed of the machine allowing it to generate at much lower speeds. Would this be cheap and easy?

I wonder why the farm-style windmill is not used more to power generators?

Will it be good for fractional Kw output?

 

[chuckey]

" down the synchronous speed of the machine " are you hoping to synchronise this to the grid? - not possible unless you can produce more then the grid voltage. Have you tried Google yet, as a clue have a look at this site :- https://www.thegreenlivingforum.net/forum/
Frank

 

[Avla 0652]

Try to use stepper motor,
they are multi pole and they work as a generator at low rotating speed.

 

[tpetar]

Thanks for all your help...

No, but I was thinking of a cheaper alternative to Nd magnets.
I was wondering to make use of a single phase or maybe a three phase induction generator instead of a car altern. with more number of poles in it preferably 8 or 10 poles which would bring down the synchronous speed of the machine allowing it to generate at much lower speeds. Would this be cheap and easy?

Will it be good for fractional Kw output?

See this link:

http://www.projectfreepower.com/wind-power/homemade-1000w-wind-turbine.html

 

[ArNvC]

Thanks again,
Yes, I've been googling around for quite a sometime and found these http://www.chinahpmg.com/?gclid=CNCW3o_Q3bYCFRF96wodzFQAqg, http://trade.indiamart.com/search.mp?search=ndfeb+magnet
Now let's get back to work.

are you hoping to synchronise this to the grid?

Not at all, just for domestic purpose.

 

[tpetar]

Its good to get few of these, wire coil, and try to do some testing, before you make some final version of device.

Check for "Home Power" magazine. You can find lots of practical expirience, suggestions, designs,...


;-)

 

[ArNvC]

Thanks 4 the info...will do that