Radial Flux Generator Project

[clintonbriley]

So is it one continuous length of sheet strip or is it broken periodically to separate the rounds?
Clint

[artv]

Clint......If I recall correctly  its' strips of 3/4"metal cut, from the actual shells of the micro-waves................a question I have,is do the laminates have to take up the space between the legs of one coil, or take up the space behind the legs themselve......because your trying to pull as much flux as possible through the copper.........just curious........artv

[clintonbriley]

a question I have,is do the laminates have to take up the space between the legs of one coil, or take up the space behind the legs themselve......because your trying to pull as much flux as possible through the copper

I don't understand what you just said ;-)  If it's not just me could you state it so I can understand it?
Clint

[artv]

Clint ..........the laminates in my opinion , are just there to create a path for the magnetic circut ........that way putting them just behind the coil legs  , would save on steel..............I don't think you need them in the holes of the coils or in between the coils.........but don't take my word for it ...there's a 99% chance I'm wrong...........artv

[clintonbriley]

Thanks artv, I understand what you mean now and of course I don't know the answer ;-)
Clint

[jeraklidis]

The laminations reduce hysteresis losses. As the rotating magnetic field switches polarity the metal (Iron in stator) has to switch its polarity as well. These changes create losses. The laminations reduce the eddy currents to that plane(plane: thickness of that individual lamination). The laminations also have a coating on them as well(ie: C3 or C4 or C5). Also they use cold rolled grain oriented or non grain oriented steel (CRNGO). Other people call it electrical steel or silicon steel. http://en.wikipedia.org/wiki/Electrical_steel
the thinner the lamination the more efficient the design. As far as wind turbines go God gives you power in the form of a velocity in a given area and you have to perfect and minimize all the losses involved.... using laminations are one way of creating a "pro" design.

transformers use thicker gauge; precision servo motors uses the thinnest gauge.

I am just finishing my laminated stator and TRUST ME ITS NOT WORTH THE TROUBLE OR THE MONEY... spend your money on lighter blades or better materials for your axial design....

 
IF MONEY IS NO OBJECT:

you can go one step further... These links are way beyond homebrew

http://www.hoganas.com/en/Products--Applications/Sintered-Components/

http://www.hoganas.com/en/Products--Applications/Soft-Magnetic-Composites/

[Flux]

"The laminations reduce hysteresis losses."

No that's not true. The hysteresis loss is a function of the steel you use. Laminations reduce eddy loss. How thin you need to make them depends on the frequency you are working at and the resistivity of the material.

With suitable thickness of lams for the chosen frequency you can keep eddy loss to a low value. The problem with using common materials such as mild steel strip or band saws is the hysteresis loss. Such cores work but will cost you most of your low wind output, they are fine in high wind areas but best avoided if you want much power below 10mph.

It'sdoubtful if slotted iron cores are worth it for small wind turbines and if you must go that way the core will be expensive. For axials there is no readily available cheap core material available and the early single rotor axials with a laminated core really didn't compare with the dual rotors in low wind performance. if you want maximum power in a gale then they do cool better than the dual rotor.

With radial designs again I don't think slotted cores are worth the effort but with high quality motor laminations available for near nothing on the scrap market the issue is a little different, even so I have abandoned slots in favour of smooth cores with the coils in the air gap. Again if you don't want low wind performance and want the cheapest solution for high winds then slotted cores are fine.Manufacturers sell on cost and rated power output so they use them but in many cases the low wind performance is not optimum.

I think this discussion will keep running for a long time as every design has compromises and each constructor will have different values for the important issues.

Flux

[clintonbriley]

So the resin composite using powdered cast iron aggregate didn't work out as well as hoped.
How much better might a similar composite of rotor metal powder have worked?
If there was an easy way to turn an old motor laminate into suitably fine powder.......
Clint

[ChrisOlson]

Again if you don't want low wind performance and want the cheapest solution for high winds then slotted cores are fine.Manufacturers sell on cost and rated power output so they use them but in many cases the low wind performance is not optimum.

I think decent low wind performance is going to be an important issue for most people.  Not everyone is fortunate enough to live in Kansas where the standard wind speed indicator is a length of log chain nailed to the top of a fence post, and if that log chain is at 45 degrees to the post you have a light spring breeze, and standing straight out from the post it means a real wind might pick up later.

It appears that's where the iron core I experimented with won't work that well.  With a 13 foot rotor the machine, I don't think, would not start turning at all until a 10-12 mph gust hit and it would take a 14-18 mph breeze to get the output on par with a dual rotor axial at the same wind speed.

We're kind of in the dog days of summer here and it takes a thunderstorm to get any real wind this time year.  But I would love to mount this generator I got on a 13 foot turbine and fly it to see what it actually does in real world conditions.  I would have to rewind it with half the turns of heavier wire to do that but I think I need to know how it actually performs on a turbine before I attempt another core design.  I've had things before that I thought wouldn't work based on bench testing (like stators designed for IRP) - but putting them on a turbine yields a different result.
--
Chris

[jeraklidis]

to flux: You are correct about the eddy currents.... and you are correct that this thread will go on and on......

[jeraklidis]

btw

To Flux: I have not forgot about our generator simulation program... It is part of my senior thesis thus will take some time. Its 1/3 of the project (another 1/3 = turbine and last 1/3 automated winding machine)...

To Chris: Have you thought about reducing the diameter of the rotor? The field strength will drop dramatically with a small change... just a thought

To All: After all this talk(and cost overruns on my design) I might have figured out a cheap work around for the home brew crowd that uses a radial design but without the expense of laminations... expect an attempt 6 months from now though (no guarantees on performance)...

[JW]

Here's more history of the forum. Im looking for something this came up.

here's what i was looking for. Its hard finding the threads im looking for.
https://www.google.com/search?q=stator+and+diode+connections&rlz=1C1VDKB_enUS1042US1042&oq=stator+and+diode+connections+&aqs=chrome..69i57j33i160l2.32575j0j7&sourceid=chrome&ie=UTF-8#imgrc=WLL-17BVVdlC6M

STAR DELTA

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