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Wanting to build miniature wind turbine, I need help

Thread starter #1
Hello all, I just signed up because I am having difficulties understand certain concepts within some designs of a wind turbine. This is the site I am mainly adhering to that I'm sure you all have seen before: How I built an electricity producing wind turbine

And here is what I believe I know so far...

Wind forces the blades to turn which then causes the motor to generate a DC electric current. This current is transferred through a fuse to a dummy load to a controller to an inverter then finally to whatever device you are wanting to power.

Where I get lost is how to connect the electronic components as well as what is compatible with what. Here is the example that I have worked up as my schematic in progress:

24v motor with a 2amp output regulated at 300rpms, and let's say it rotates at 150rpms from the wind. This then generates 12V at 1A that travels through the cords to the inverter where it converts it to 110V AC. Are these all compatible?

What about this situation: 24V, 2A, 200rpms spinning at 150 rpms creates 18V correct? So what effect would this have if I were to use a 12V DC inverter? How can I fix this as the wind will not be steady.

In summary my main concerns are how can I determine compatibility among parts, what is and how do I use a dummy load, how do I hook up (and maybe create) the controller?
 

audioguru

Well-Known Member
Most Helpful Member
#2
12V at 1A is only 12W. An inverter needs about 40W just to start plus more to do any work. You need a big generator and a big propeller to produce hundreds or thousands of Watts.

The output voltage of a generator changes when its speed changes. So you need a voltage regulator. A linear regulator gets very hot so use a switching regulator or a shunt regulator.
 
Thread starter #3
Thanks so much for a response, anything helps!

So W is V/A? If that is the case then what if I drop the A? Also what if the inverter is one of those small, single outlet car adapter varieties. Would it need a whole lot just to power a AA battery recharger?

Where in the line of power does the voltage regulator need to be? Immediately after the motor?

I'm not looking for anything to power a laptop or something that needs a little more juice. Just thinking along the lines of rechargeable batteries, iPods, etc.
 

audioguru

Well-Known Member
Most Helpful Member
#4
You don't need an inverter if you are using a wind generator to make a small amount of low voltage DC.

AA Ni-MH cells that are rated at 2500mAh can be charged from 1.5V per cell at 250mA for about 11 hours for dead cells.
A shunt regulator is used to "throw away" extra voltage by applying brakes the turbine so that the blades do not spin too fast.
 

Boncuk

New Member
#5
Hi rosko44,

talking about a miniature wind generator you're obviously also talking about "miniature power".

It takes a 3m diameter 3-blade propeller to produce 500W at wind speeds of 40kmh with rapidly decreasing output power at lower wind speeds.

Using an inverter to step up to 110V (115) and a good efficiency of e.g. 70% the 500W will detereorate to 350W.

I suggest to use bipolar stepper motors rated for the power you want to produce subtracting at least 20% of its nominal power for the output power.

Each coil would connect to a bridge rectifier and both of them could be paralled for power output (unregulated).

Example: Stepper motor rating 12V/2A per coil = 12V/4A in parallel (pretty big size already) would give you 38.4VA power output at 80% efficiency.

A stepper motor has a big advantage over DC-motors supplying relatively high power at low rpm already.

(Connecting an LED to one winding of the stepper motor of a 3 1/2 inch floppy drive makes the LEDs turn on brightly just by twisting the drive axle by hand)

To keep the "generator" miniature you could use four stepper motors mounted in a B17 (flying fortress) or Shackleton bomber model at a power output to illuminate your garden at any time charging a medium size SLA-battery with all four outputs (stabilized) using 40cm dia wooden propellers which you can purchase at aircraft model shops.

The model would give some more benefit, telling you the wind direction and speed if you use the output frequency of one stepper motor for an rpm-meter calibrated to indicate wind speed, not mentioning that the "generator" would be unique.

Big size wind generators also produce lots of noise "Whap, whap, whap" and using one of that kind make sure it is located about 500m away from your house.

Additional care has to be taken to feather the propeller at wind speeds too high for proper function (blade tips in the supersonic range=self destruction) if using big size wind generators.

Regards

Boncuk
 
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Thread starter #6
This sounds much more like what I had in mind, thank you. I will explore this route and see what I come up with.

I originally saw Febot Recharges Batteries by Ji-yun Kim, Soon-young Yang & Hwan-ju Jeon Yanko Design and did a little more research and came across the site previously mentioned and I thought how can I make one sort of in between.

What exactly does a bridge rectifier do? Condense the leads from both (or more) motors?

The idea I've been playing with (mind you I have no idea of what's feasible or ridiculous) is that if I can dismantle the input end of a single outlet car adapter inverter and attach it to the "generator's" output in order to plug things in such as iPod chargers.
 
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#7
Hello all, I just signed up because I am having difficulties understand certain concepts within some designs of a wind turbine. This is the site I am mainly adhering to that I'm sure you all have seen before: How I built an electricity producing wind turbine

And here is what I believe I know so far...

Wind forces the blades to turn which then causes the motor to generate a DC electric current. This current is transferred through a fuse to a dummy load to a controller to an inverter then finally to whatever device you are wanting to power.

Where I get lost is how to connect the electronic components as well as what is compatible with what. Here is the example that I have worked up as my schematic in progress:

24v motor with a 2amp output regulated at 300rpms, and let's say it rotates at 150rpms from the wind. This then generates 12V at 1A that travels through the cords to the inverter where it converts it to 110V AC. Are these all compatible?

What about this situation: 24V, 2A, 200rpms spinning at 150 rpms creates 18V correct? So what effect would this have if I were to use a 12V DC inverter? How can I fix this as the wind will not be steady.

In summary my main concerns are how can I determine compatibility among parts, what is and how do I use a dummy load, how do I hook up (and maybe create) the controller?
Why dont you charge a lead acid battery? at 13.9 volts and 2-3 amp whole day with any wind speeds is good. then inverter can be used to draw power from the battery. i thing a 200amp battery can serve you well. and for wind turbine you can go for a tread mill motor. find it of a low RPM and maximum current and voltage upto 18 volts.
 

bryan1

Well-Known Member
#8
Why dont you charge a lead acid battery? at 13.9 volts and 2-3 amp whole day with any wind speeds is good. then inverter can be used to draw power from the battery. i thing a 200amp battery can serve you well. and for wind turbine you can go for a tread mill motor. find it of a low RPM and maximum current and voltage upto 18 volts.
A 200ah battery at the C/10 rate is 20 amps and if one thinks a mini wind generator can supply anything like that then ya dreaming. Small wind generators without much copper need high speeds just to reach an amp @ 12 volts, then one will see the small output shaft sheer off due to the torque induced on the shaft or the blades fly apart.....
 

shortbus=

Well-Known Member
#9
Nuts and Volts magazine has been running a alternative energy series, that with the Jan. 2010 issue started the Windpower phase. A lot of good information on making a couple of different working generators. Just the one on the different types and ways that blades work is worth the time to hunt down the articles.
 
#10
c/10 is maximum charge you can give to a battery. not the least. you can charge it below that. the only thing is that you must be able to push the charge in the battery. i dont recommend high RPM. even our thermal power station generators have 3000 rpm. there are many generator motors available working at low RPM. and use vertical turbine instead of horizontal axis one.
 
#11
I start to write in this thread because I'm in a similar condition.
I want to build a small wind turbine - generator. But my question is about the basics of rotors and stator.
As far I know, I need 2 rotor discs that contains the magnets and a stator disc that contains the coils.
I've read something about that the number of coils must be multiple of 3. That is the only thing I know. Then, I don't know if the number of magnets in each disc need to be like the same number of coils.
That is true? Any other information will be welcomed.
 
#12
years ago ,in college we put together a wind turbine using a 60amp AC Delco alternator for a guy for his hunting camp to maintain a charge in a pair of old car batteries.
We then made up a under-drive pulley for the alternator, attached the turbine to a separate shaft and bearings,with a larger pulley mounted in the middle of that shaft,made from light weight aluminium.
We then used a serpentine belt to mate the two. We went for a 1:3 ratio fan to alternator.
It worked exceptionally well only the alternator required a small current to excite the field coils..That was its handy cap.

in later years thinking back on that same project and the ease of acquiring DC motor's. Given a similar set up only with a low rpm DC motor, say 24V with 1000rpm, using a drill press a guy could determine how fast a motor would have to spin to produce a 24v current, I'm assuming a bridge rectifier could be used to stop the generator from being a motor,
I should also mention a simple centrifugal clutch could be used to govern the fan in high wind situations

Right now I have two little projects on my bench that would run a lamp on my kids bike,using motors from an old printer, simple flick of the shaft with my fingers will instantly power a led.When coupled to a drill running 800rpm the motor produces 14.7 volt, more than enough to keep a few leds lit.
 
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#13
Depending on how you configure it, an axial flux PM generator can produce power at low RPMS or high RPMs. There's plenty of information out there about building a AFPM Wind Turbine.
 

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