10 ft windgenny

[dinges]

I'm finally making preparations for the first real windgenny (but the 3rd axial flux generator). I'd like to know whether my figures are more or less ok for the alternator itself. It's going to be a 10footer, but initially will probably only run with an 8ft prop (for about a year or so, for testing), by opening air-gap.

prop 10ft (8ft initially)

abt. 200W power

24. V system voltage (externally rewireable for star or delta)
    
9. /12 dual rotor axial flux
   
   

magnets N40 50*25*12.5 (2"x1"x.5")

coils:

70. turns each
    
3. coils/phase
   
   

wiresize 1.6 mm (AWG14) (but perhaps 1.5mm, not sure yet)

coil thickness 8mm (5/16"), a bit thinner than the usual 10mm (3/8")

I think I'm getting pretty close to the correct values, but I'd like to know what youse think. The alternator is supposed to be a fairly standard 10foot generator, but as said, will also have to be able to run with an 8ft. prop for a while (perhaps forever?). The alternator however should be built to handle the 10ft prop and power.

Peter.

[Flux]

You are in the right area, but I don't think you will gain anything by going for the thin stator. I think you will have a job to get the 1.5mm in at that thickness.

I would take the stator up to 1/2" thick and go for at least 1.6mm, with care you could do even thicker.

Flux

[willib]

Peter is this going to be a "standard" rotor  bolted in the middle? or a peteroter bolted together at the perimeter?

a quick calculation gives me 6.5V peak per coil ..do-able, but,at what rpm and wind speed?

i agree with flux,

You are going to have a hard time getting the voltage you need (24V) with such a thin stator .and what size rotors are you thinking about?

[dinges]

Thanks for the response.

You may be right, that stator may be a bit on the thin side. Think I'll go for 10mm (3/8"). Though the wire (1.5mm) should fit in the original size of the coils. As far as wire size goes, 1.6mm may be the better way indeed. My preference was for that size too.

Willib, as far as RPM and windspeed goes, I haven't bothered to calculate it, figuring it would be a fairly standard 10ft Dan-design. Like said, initially it would probably run with a 8ft prop, but this is just a matter of opening the airgap (with resulting loss in power).

Exact rotor size would be a function of coil size. But initial sketches would indicate about 30cm (1ft).

BTW, does anyone know of a 10footer like the Dans, built with my magnets (N40 2"x1"x.5")? I haven't found a reference, but if anyone knows of a description, I'd like to hear about it.

Peter.

[dinges]

I didn't make it clear in the original post, but the coils will be 10mm (3/8"); the entire stator will be a little thicker ofcourse, probably very near to the 1/2" that Flux recommends.

Peter.

[seanchan00]

Hi Peter,

This maybe what you are looking for. I made almost exact copy of Tim"s turbine and I am currently running it on an 8 footer. My wind here unfortunately in so poor in my area I am forced to go to 11 even 12 feet blades and close the airgap. Lots of problems and lots of fun and learning first hand.

http://www.otherpower.com/timsturbine.html

SeanChan.

[Flux]

I have not used the imperial magnets but the 46 x 30 x 10mm N40 will produce 0.65T in an 18mm gap. The 1/2" thick should manage this in a gap of at least 20mm.

If you run this on an 8ft prop you will end up opening the gap to about 1" so there is no need to squeeze the stator into anything thinner. Even with the 10ft prop the cut in will be about 140 rpm and 20mm airgap should just keep you out of stall.

Unless you use mppt the thicker wire will make little difference but if you need extra resistance it would be far better to add it to the line rather than have it as heat in the stator.

With 8ft unless you are in a dreadful wind area and want everything in low winds I would open the gap to raise cut in to 200 rpm or a bit above. This will give you a better overall result than keeping the silly low cut in and having to add lots of resistance to the line.

Would be a good candidate for keeping the low speed on 8ft and using the star/Jerry connection as a simple way to do a star/delta change, it's a bit rough at 8ft but manageable, a simple 2917 tacho chip sensing frequency and operating a 2 pole relay should not add too much complexity. 1kW should be within reach at 8ft.

Flux

[dinges]

Thanks!

That Tim-turbine was exactly what I was looking for. I thought I knew all the pages on otherpower.com, apparently not...

Flux, understood. I thought it would be wise to keep airgap at minimum (an error in my previous 2 ax.flux gennies), but it can be overdone, I understand. Thought it would make better use of the magnets. I do intend to build something that will switch between star and delta, and thus the genny should be prepared/ready for it (all 3 phases having each 2 wires to the environment). But 1kW from an 8ft prop... Wow.

Peter.