Stators

Winding the coils and making the stator

Stators

Postby gyrosa on Sun May 25, 2008 2:31 pm

About 30 years ago I was very involved with wind power in the Karoo. These were all DC generator versions. Subsequently I have been looking at the latest alternator versions, but what I have found starnge is that all the latest alternator versions are open core coils. Surely a core using laminated soft iron would be more efficient and would also allow for smaller coils, thus resulting in more coils per circumference of the stator.
Regarding the props. As I am also a pilot and flight instructor by trade, I have done some study into propellers. The formula is P= 2Pi R tan theta, Where = pitch, R is the radius of the prop at any given point. This allows the pitch to remain constant throughout the blade length eg if you choose a 24 inch pitch, the pitch would remain at 24 inches throughout the length of the blade.
With regards to the props. I am also working on a system that will allow the prop to feather in high winds and become finer pitched in lower wind speeds. The reason for this is that it is governed purely by the speed of the blades and thus becomes a constant speed system.
Any comments are welcome.
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Re: Stators

Postby windgat on Sun Jun 01, 2008 1:47 pm

Hi Gyrosa. My understanding is that the modern 'air core' design is possible because of rare earth magnets. I know this causes confusion sometimes, as a generators power used to be approx. measured by the weight of iron in the core.
Not sure I understand the 'constant speed system'. What is meant by that?
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Re: Stators

Postby gyrosa on Wed Jun 04, 2008 12:10 am

Hi Windgat,
The constant speed idea is derived from the standard aviation term whereby the prop on the engine of the aircraft is used to maintain a constant speed (pre-set by the pilot) on the engine, irrespective of the power settings used.
My idea is based on this idea, (as was employed on the Jacobs windcharger of many years ago) where the prop blades actually are twisted to a coarser or finer pitch (similar to that done in aircraft) as the speed increases or decreases.
As the blades start to turn, say up to about 50rpm, the rotating field will not be energised at all. After about 50 rpm the blades will start to twist, and the mechanics of this will set off a micro switch, thus energising the rototating field (rotor) to a limited extend. The faster the blades turn, the more they become twisted into a coarser mode, tripping more micro's and changing the field strength.
I am fortunate in that I have the blades available as well as a lathe and the now how (I work with them everyday in the aviation game).
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Re: Stators

Postby windgat on Thu Jun 05, 2008 10:00 am

Wow, sounds interesting! As a test of my understanding, could the same effect be achieved used permanent magnets, and moving the rotors (magnets) closer to the coils at higher wind speeds (using some kind of centrifugal mechanism)?

I think a factor is also that at low wind speeds, there is so little power in the wind (velocity cubed rule) that it is not worth having a mechanism to try and get power at those speeds.
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Re: Stators

Postby gyrosa on Tue Jun 10, 2008 10:41 pm

Hi Windgat
Yes, the principle can be applied using magnets as well and this is the easier way out, no doubt on that. The basic princple was also applied to the Jacobs wind generators of years ago. The other version was two semi circular plates, placed at right angles to the prop blades, in such a manner that when the speed became too high, these plates would move outwards, thereby inducing drag and slow the system down. This system was used on the 6v and 12v Wincharger.
My method I think (and hope) should be more effective as I am also looking at a manual method of feathering the blades to stop their rotation.
In any case, I shall be in Cape Town within the next two or so months, and if you are available, we can swop ideas.
Regards
gyrosa
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Re: Stators

Postby windgat on Tue Jun 17, 2008 9:11 am

Hi Gyrosa. Interesting... and it would be interesting to swap ideas, so email me if you have some time spare when in Cape Town.
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