Newbies > Newbies
Small Wind Generator/Motor
sr71p38:
I am definitely a Newbie to the wind generation community. If this topic has been discussed I apologize I looked through a lot of the post but might have missed it.
I am working on building my first wind generator and just when I think I am making progress I run into a new brick wall. I built a nacelle based on a Windstream Permanent Magnet DC Generator in a direct drive configuration. I was running the blades at over 300 RPM and getting only milliamps of current, the voltage is 13.9 V or 24 V depending on the battery configuration I use. Didn't realize I should look at the RPM vs Amp curves before I started this whole thing. Seem this particular generator needs to run at over 1000 RPM to produce 1 amp at 12 volts. So basically I am getting no real power out of this.
I was wondering if anyone has any suggestion for a generator that is approximately 2.5" in diameter that will actually produce some power at 300 RPM? I am not looking to produce a ton, I would be happy with 40 Watts, or even 10 Watts at this point.
I am also open to other suggestions, like having one custom build, adding an inline gearbox, or even a transformer if that might help. I was hoping not to redo the Nacelle but if there is a generator at 3" that will do this, I guess I will do what makes sense.
mab:
I seem to recall folks using Amtech motors - it's a few years back though - could try searching the old posts.
otherwise look & see if you can find a small high voltage dc motor, but i don't know what's out there TBH.
bigrockcandymountain:
1000 rpm might be a perfectly ok speed depending on the diameter of your rotor. If you are only looking for 10w you might be ok with a pretty small diameter. What did you have in mind? Sounds like maybe you have blades already. How big are they?
Bruce S:
sr71p38
Welcome to the forum.
Could you give us a little bit more info on your build? There may be a few items that can be tweaked to get you a bit more out of your current unit.
Could things we could use is wire dia imperial or Metric ( we speak both ) magnets use (i.e. Ceramic, Neo, cobalt, etc)
How you are getting the power readings, HAWT Blades 2,3 or ??, VAWT S-type, squirrel cage, etc or test bed driven , drill, drill press or??.
ON a side note your user name leads me to thing your are either a pilot, or aviation enthusiast?
Again Welcome aboard
Bruce S
SparWeb:
Hi
Welcome to Fieldlines!
You might want to stick with used DC motors to experiment with, but watch the specs carefully.
A very rough guide:
Diam. Speed Wind Power Electric Output
2 feet 1400 RPM Pwind=60 Watt Pelectric = 30 Watt
3 feet 950 RPM Pwind=130 Watt Pelectric = 65 Watt
4 feet 700 RPM Pwind=230 Watt Pelectric = 115 Watt
5 feet 560 RPM Pwind=350 Watt Pelectric = 175 Watt
This is based on 20 mph wind and blades turning with TSR = 5.0 and blade efficiency 40% and electric efficiency 50%.
This should help you set expectations, because a small prop won't get the wind energy needed to run a large generator or a heavy electrical load. You can use it the other way, too. If you want to power a 120 Watt load in 20MPH wind, then you'll need a rotor 4 feet or bigger, or make what you have more efficient than what I've assumed them to be.
Thanks for joining, and you are welcome to share everything you do and all the fun it causes.
And.... the blackbird takes it every time.
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