BIG Wind generator start

[amiklic1]

Ok Now!

I'm starting to build a big wind generator based on axial flux alternator seen many times on this board. I'll use factory manufactured blades (fiberglass-epoxy ones), so I need to calculate and build the alt, alt frame (body), controls (furling tail?).

Here is what I expect to get:

1. The blades are around 8 meters long (some more diameter could get with hub diameter, but not much).
   
2. I expect approx 10 kW power in 10 m/s wind speed.
   
3. I plan to use  some grid tie inverter to connect that with the grid ( I already have some offers from manufacturers)
   
4. It has to be high-voltage device, with direct voltage output in the range from 240 - 450 volts.
   
5. I'll use 100x50x25 mm N40 NdFeB magnets (really scary ones),
   
   

I would like to have your opinion, no matter how simple and useless it is.

I would just like to state some things: I CAN connect that device with the grid in my country without many problems, as long as inverter is delivering good voltage, frequency ad current into it, and it should.

I HAVE the possibility to build the frame and the machine according to all standards, to measure and calculate all forces applied to the parts, and the blades (with max. forces applied to them) are not going to be homebrew, but quality factory built.

I would like to put some larger blades, to make it working into lower winds, to increase its performance thru the year.

I would like to use furling tail, because I think no other type of protection is as simple and as good as this one.

I would like to use slip rings and brushes on yaw bearing, because the machine is going to be left alone for a month after it's mounted.

I you were thinking about building something THIS big (and if you're sane, its obvious you don't), where would you start? How many coils, magnet rotor diameter....??

Thank you all in advance.

[Tallwind82]

Sounds scary, wish I had the cash to try one that big :-)

First of all, your expected output seems a little low for your blade size. Did you mean 8 meter diameter or 8 meter radius (8 meter blades)?

According to the spreadsheet I made a few months back you should be able to extract about 50KW from a 10m/s wind with a 16m diameter turbine, not factoring in the alternator efficiency. 8m diameter would give you somewhere around 10KW @ 10 m/s.

I think your biggest challenge is going to be attaining the desired voltage directly from the mill.

Assuming you meant 8m Diameter:

Using Dan's 17' mill as a reference I would expect you would need about 36 of the magnets you specified per rotor. Wire gauge and # of turns is a little beyond my current knowledge to estimate, but I expect that to attain your desired voltage you might want either larger magnets or more magnets. Also, to fit that many mags of the size you specified would need 52" (1.3m)rotors. That's twice the rotor/turbine ratio that Dan usually uses.

One more question, single phase or three phase?

Good luck and have fun

Robert G

[amiklic1]

I just get the details of the grid-tie inverter I could use, and in it's specifications stays that input voltage (it's three phase inverter, 10 kW) is in the range from 380 to 600 volts.

I don't know can I use something like that, or it's better to use one phase inverter. One phase is limited to input voltages from 220 to 320 volts.

I am a bit reserved because the input (or wind generator, as stated) frequency is 35-75 Hz for three phase, and 30-60 Hz for single phase unit.