steel laminated stators

[phil b]

I am currently thinking about the construction of my third wind generator.

So, I'm going back to basics and revisiting concepts from the board.

The commercial wind generator manufacturers seem to be using a row of magnets mounted either inside or outside of a steel laminated stator.

The folks on this board originally used laminate backing also. When the dual magnet

rotor concept came around, it seems everyone dropped the laminated stators.

They were hard to wind, labor intensive, heavy, and silicon steel was not readily available.

Cogging also seemed to be a problem in some cases.

question 1

If the same amount of magnetic material, as used in a dual rotor machine,

is mounted axially on one rotor, with a laminate behind the stator, would there be more power generated than a dual rotor system?

question 2

If steel laminate is cut to fit around and/or through the center of the

individual coils, then poured in resin to make the stator on a dual rotor machine,

Would the output be higher than just using magnet wire in the stator?

question 3

Are there other more efficient alternatives I'm overlooking?

Thanks for your comments,

phil b

[DanB]

Hi Phil -

"The folks on this board originally used laminate backing also. When the dual magnet

rotor concept came around, it seems everyone dropped the laminated stators.

They were hard to wind, labor intensive, heavy, and silicon steel was not readily available.

Cogging also seemed to be a problem in some cases."

When I was using laminates, I'd press the coils over the top of the laminates - so hopefully the coils would be very thin.  The laminates existed behind the coils  - not inside, so cogging was not a problem.  Cogging could become an issue when we slot the laminates and put the coils inside them - kind of tricky to do that, but he benifit is a much smaller airgap and much less magnetic material required.  The drawback there is more work - and possibly issues with cogging.  Also - in a single rotor axial flux machine with laminates the magnet rotor is always 'pulling hard' against the stator, and when current is flowing, the stator will vibrate.   The bearing is always under some load.  This makes it a bit stiffer to turn I think, and unless the stator is very rigid and attached very well I would expect it to either warp, or come loose enough so that the magnets could rub on the stator.

"question 1

If the same amount of magnetic material, as used in a dual rotor machine,

is mounted axially on one rotor, with a laminate behind the stator, would there be more power generated than a dual rotor system?"

I haven't really tested this too much, but yes - I think it would be similar, assuming that the coils are the same thickness, and the laminates exist behind the coils, not around them.  The last laminated machine I made had 1.8" diameter x 1" thick magnets on the rotor, a 1/2" thick stator, and laminates behind the stator.  Shortly after that I made some dual rotor machines (with identical stators) and each rotor had 2" dia X 1/2" thick magnets, and the dual rotor machines were slightly more powerful at any given rpm, but they had just slightly more magnetic material in them (2" diameter instead of 1.8" diameter).  

"question 2

If steel laminate is cut to fit around and/or through the center of the

individual coils, then poured in resin to make the stator on a dual rotor machine,

Would the output be higher than just using magnet wire in the stator?"

Yes - but you'd be hard pressed to come up with something that didn't cog.  The vibration of the stator might be fairly intense.  You'd have iron losses again, though they may not be too big an issue.  I think it would be tricky, the forces of the rotor pulling on that during assembly might be hard to deal with.  It'd be fun to see someone do it though, it might workout fine once some things were figured out.  We only figure out by doing...

"question 3

Are there other more efficient alternatives I'm overlooking?"

I tend to think laminates are very nice in some cases.  Coils cool better when surrounded by steel, thats one big advantage - although overheating has not yet been a problem with stators of only copper and resin.  I tend to think laminated stators are very nice/handy in radial flux machines - it's tricky

 in axial flux machines.

[Flux]

Question 1

If you use the same amount of magnet material to produce twice as many poles on one disc you will get more than a dual rotor. If you stack the magnets for the same number of poles you will not.

Q 2

Yes you will get more output but it will cog badly.

Q 3

What do you mean by efficiency?. Do you really mean more output for a given cost of magnet.

If you want to use iron cores the best thing is to stick to radial designs as there are fairly low loss cores readily available for motors. There are no cores specifically produced for axial designs and you have to buy expensive silicon steel or put up with low grade core material and lots of iron loss. If you are not interested in winds below 10 mph then it may not matter.

There is no difference between the motor conversions that Zubbly does and the commercial slotted core windings. It is easier mechanically if the magnets are outside the core but there are no standard punchings available on the cheap.

The great advantage of the axial design is the ease of manufacture as there are no constraints on air gap dimensions. In every other respect a radial design has advantages especially when you want overlapped coil windings.

If you have machining facilities you can use the old brake drum idea which is the radial equivalent of an axial single rotor with the advantage of reasonable grade motor cores being available. The thing is not really practical unless you can machine your magnet drum as finding ready made bits of the correct dimensions is a problem.

If you have the facilities it is a good method with quite modest iron losses and a better use of magnet material. It will not produce the output of a slotted stator but will work better in light wind as the iron losses will be a lot lower.

There is no perfect solution each method has its advantages and snags. You have to decide if magnet cost is the first issue or whether ease of construction and the lack of iron loss more than makes up for it.

Don't forget that commercial manufacturers have to produce an impressive rating at minimum cost, in a low wind area it may not be the best option.

Flux

[zubbly]

hello phil b!

#1 in my opinion, whenever a laminate material is used, you will get the most available power from your design.

#2  again i think the same applies, laminates = more power from your system.

#3  more bang for the buck= using laminates and less magnet material and getting considerable output for your efforts and dollars.

hope no one takes me the wrong way. i think the dual rotor without laminates is a marvelous design in its performance and and simplicity that most any of us can build.

it is just my preference to get the most out of a given set of mags with induction conversion. you have a tough frame with great bearings/shaft, the best in laminates, and i have also come to the conclusion that using a stock 230/460 volt winding will suit and is re-connectable to suit most charging situations that we may want. they seem to perform very well with props carved with a tsr7. the cogging issue has been addressed with using skewed magnets which could also be applied to single rotor designs with laminates.

i have made quite a few alternators from induction motors is the last couple of years and have been compiling information that i share as most everyone else here does.

if you wish to view some of my information, you may search my posts under "zubbly" and you may also view much of it at the IRC gallery. http://www.anotherpower.com/gallery/zubbly/3hpelectro45.  there are a total of 18 pages of pictures here covering everything from props, rotor conversion,rewinding and addition of leads to existing windings.

hope this helps you phil and gives you some other possible avenues to consider.

have fun!!

zubbly

[zubbly]

sorry phil b, the proper link to get to the gallery is

http://www.anotherpower.com/gallery/zubbly

[tecker]

You have to consider the horsepower you can get from your swept area first when you design in laminants .The motor conversions have small rotors and a short approach and breakaway angle from the core segments .When you go out 10 inches or so you need mucho

more power to amp past the core segments.

[ghurd]

People ARE still building them.  They just don't seem as exciting as most of the others.

"...single rotor axial flux machine with laminates the magnet rotor is always 'pulling hard' against the stator..."

I'm working on one now with the magnets at the rear, pulling 'into the wind'. It can hurt, right?

Just bike parts and tramsformer lams.

G-

[phil b]

It seems iron is best if building radial and axial is best for resin and copper stators. I'm going to do more research.

Zubbly, I've looked at the pics, but can't seem to find the step by step motor modifications I remember from a while back. Can you help me out?

Thanks to all for the comments.

phil b

[phil b]

Zubbly, I found part 1 and 3 in your diary entries. Do you have more?

Thanks

phil

[TomW]

phil;

I have the whole set in one file here in my files:

http://www.otherpower.com/images/scimages/4/z_conversion_all.pdf

Happy reading!

TomW