Coils and magnets, to produce electricity.

[cobra1]

Ok, so iv been looking around on the net for a few days looking for ways to make a half decent wind turbine.
Iv so far found that if i use 9 coils and 12 magnets i can produce a 3 phase output, if i wind my coils to have 70 turns on each coil, i can easily generate 24v.
The magnets described are N35 grade.

Overall this setup is supposed to easily deliver 700w - 1000w in 10 - 15mph winds

Ok, so thats the basic setup.

Here come the questions,

How would i go about increasing the current output, the voltage ideally should remain at 24v
Also how would i go about making them produce better currents at slower speeds?

At the moment this is all on paper so if the setup needed changing then i can do that.

 

[crutschow]

Building high power, efficient, generators is not a do-it-yourself project. Translating from paper to machine requires coil winding equipment, precise machine tools and the knowledge to operate them.

 

[alec_t]

Overall this setup is supposed to easily deliver 700w - 1000w in 10 - 15mph winds

Only with a large turbine (but don't ask me to define large!)

How would i go about increasing the current output, the voltage ideally should remain at 24v

The only way to get increased current from a fixed 24V is to decrease the resistance of the windings and load (Ohm's Law). That implies thicker wire and hence bigger coils.

Also how would i go about making them produce better currents at slower speeds?

At lower speeds the output voltage will drop. So the answer is, again, reduce resistance. But perhaps by 'better currents' you meant higher voltage?

I think you need to read up about wind turbines, and how their output varies with wind speed, before you go ahead with the build.

 

[RCinFLA]

At 20 mph windspeed, on a well designed multiblade windmill, power output is about 180 watts per square meter of swept area. Power is proportional to wind velocity cubed. At 10 mph windspeed it drops to about 22 watts per sq. meter swept area.

For 700 watts output at 10 mph windspeed you need 21 feet diameter rotor.

 

[cobra1]

Cheers for the answers guys, primarily this project is to demonstrate a new design in frictionless bearings. obviously if i could also get some decent power from it that would be a bonus. The design for the generator is an axial flux design and is 12" diameter. It would be fitted to a VAWT type turbine.

 

[carbonzit]

Cheers for the answers guys, primarily this project is to demonstrate a new design in frictionless bearings.

Ouch. Please don't say "frictionless bearings". That puts you in the same camp with countless other crackpots, like those who believe in perpetual motion.

Say, instead, "low-friction bearings".

 

[cobra1]

lol, when i say frictionless i mean no mechanical bearings, i know that thers friction from air and also the drag from the blades etc etc

The idea is to have something with pretty much zero maintainence

 

[shortbus=]

lol, when i say frictionless i mean no mechanical bearings, i know that thers friction from air and also the drag from the blades etc etc

The idea is to have something with pretty much zero maintainence

Can you share your "no mechanical bearing" idea?

 

[carbonzit]

Maybe the generator uses maglev?

 

[Robin2]

One thing you haven't mentioned is how fast the turbine and the generator will rotate. Wind turbines generally turn slowly and small generators usually work at high speed.

As far as I know VA turbines are a lot less efficient than regular "propeller" turbines.

You also have not mentioned how you will match the load to the turbine output. If you have a heavy load the turbine will stall at low windspeeds. Someone told me that wind turbines react very quickly to short term changes in windspeed which makes power matching complicated if the turbine is not to stall in a brief lull.

The alternative to a complex power matching system would seem to be a generator that is underpowered compared to the turbine - hence wasting potential wind power in return for simplicity.

 

[alec_t]

the generator is an axial flux design and is 12" diameter

Prepare to be disappointed with the output power. Who reckoned you could get 700-1000W out of that? See post #4.

 

[cobra1]

At present i am not prepared to share the exact workings of the "no mechanicaql bearings" idea. But i will give general info on what i have done, you ask the questions and i will answer them, just dont ask for drawings, plans, suppliers etc. The figures were given on a PDF from Hugh Piggot. It was for a 10' turbine. i understand now that the turbine diameter is what governs the amount of wind power it can harness.