Author Topic: Radial Alt Thoughts (Read 3170 times)

vawtman · « **on:** November 03, 2007, 04:20:54 PM »

Wonder if the losses associated with a stationary steel backing would be reduced?

If so, would it be worth a try?

Thanks

ghurd · « **Reply #1 on:** November 03, 2007, 10:33:17 AM »

Rotating the laminations is like adding a 2nd disk. It should help a lot. It wouldn't need to be laminations, it could be solid.

But it would be even better, if the rotating disk is there anyway, to add magnets and have a dual rotor.

Single disk with stationary laminations is easier than 2 disks. I think thats why it is usually done. Thats why I keep doing/trying it.

G-

vawtman · « **Reply #2 on:** November 03, 2007, 10:49:03 AM »

Thanks Ghurd

A solid steel band with no lams would make life easier.

electrondady1 · « **Reply #3 on:** November 03, 2007, 06:47:38 PM »

hey vman,

getting kind of curious. did you do a test coil yet.?

vawtman · « **Reply #4 on:** November 03, 2007, 07:13:20 PM »

No i didnt edad

Ive thought long and hard about the big picture and with that many mags spinning around stationary steel no matter how well i did the stator there would be or could be lots of unnessesary drag.

The wheel is 4in wide so i can bolt and weld an outer band to it.After that i will drop a coil in.

Fungus gave me a thought on irc for the stator.

electrondady1 · « **Reply #5 on:** November 04, 2007, 06:29:52 AM »

your wise to be cautious.

youve made a big investment in mags

and it would be good to get the most out of them.

i never experimented with a stationary return bath,(your wire wound stator backing)

i think you might be dealing with what they call iron loss and with the scale your building on it might have a major impact.

the only down side i can see to a dual rotor radial like you are thinking about is

the placement of the stator.

you would need some fine tuning on the placement.

finnsawyer · « **Reply #6 on:** November 04, 2007, 09:04:54 AM »

This sounds like a progression from my suggestion to make the iron behind the stator rotate with the rotor. As I recall you were going to use 72 magnets, so you will get 72 flux reversals (36 cycles) through a coil for every revolution of the rotor. So, what would the frequency be at your normal operating RPM (not cut-in, but higher)? I mention this because there is an experiment you can do if you can get hold of an oscilloscope. Since your band will be in the form of a ring, if you wind two coils on it, it will form a continuous iron path for magnetic flux. You could energize one coil at 60 or 50 hertz through an isolation transformer (to avoid grounding problems). You then put the scope in the X-Y mode, connect the coil with the source voltage to the X input and the second, sense coil to the Y input. The scope will then show you the B-H curve, and will show the hysteresis if you can drive the magnetic flux hard enough. You might find that you would need to use a smaller ring of the same iron to reach saturation. Note that the flux paths when the alternator is constructed will be a lot shorter than the path around the entire band by itself.

finnsawyer · « **Reply #7 on:** November 04, 2007, 09:44:12 AM »

This is not quite right. The magnetic field H is driven by the current in the source coil. So, to detect that current and consequently the magnetic field we need to insert a resistor in series with the source coil. The voltage across the resistor is then fed to the X-input.

vawtman · « **Reply #8 on:** November 04, 2007, 11:56:19 AM »

Boy Finsawyer i like your thoughts but everytime you offered me advice you had to go back and rethink.

Thanks for trying though.

I know its not easy dealing with nutcases.

electrondady1 · « **Reply #9 on:** November 04, 2007, 09:02:40 PM »

vman ,

how far will the mill be from your house?

electrondady1 · « **Reply #10 on:** November 05, 2007, 06:13:01 AM »

the reason i ask is it might be practical

to try to harvest the heat your stator will produce.

if you are going with a dual rotor radial design your coils will probably be air core and the stator isolated from any iron backing.

i think it will get hot.

since your are building the mill as a heat source it might be something to try to incorporate into the design of your stator.

finnsawyer · « **Reply #11 on:** November 05, 2007, 08:19:23 AM »

It's not that I have to rethink, but that I make mistakes. The older I get the more mistakes I make. Do you think there might be a connection? And no, I don't think you are a nut case. The experiment I suggest is one that EE students used to have to do. If you know the source coil resistance and the value of the test resistor and the value of the current you can in principle find the power loss due to hysteresis. The problem is that the source voltage and source current may not be in time phase due to the inductance of the source coil. This complicates the calculation of the power going into the source coil. Still, it can be done if you find the phase angle between the source voltage and the source current. That can be done by plotting the source current versus the source voltage in X-Y mode on the scope. The phase angle is proportional to the angle of the resulting ellipse. You need to know the voltage values accurately.

windstuffnow · « **Reply #12 on:** November 05, 2007, 01:38:51 PM »

vman... just out of curiosity why not build a smaller unit and simply use a redrive? Don't take this wrong by any means and I mean no disrespect, I actually think the unit your building is pretty cool. Anyway, my point is, if you build a smaller unit and use a redrive the cost and labor would be considerably less. The losses in the belt/chain/gear would surely be made up for in costs and/or losses on the larger unit. The amount of money spent on magnets for that one alternator could be used to build a couple alternators in the same power range, maybe more...?

Just food for thought... although, no matter what it cost's I'd like to see the big one running.

.

vawtman · « **Reply #13 on:** November 05, 2007, 06:22:41 PM »

Thanks Ed and congrats on getting another article in a magazine.

I just think something like this would be a good design over gearing.Plus, like you said will be cool until it melts.

Whats your opinion on the outer band rotating?Axial fluxish but mags only on the main rotor.

Its a labor of love :>}

vawtman · « **Reply #14 on:** November 05, 2007, 06:28:51 PM »

Fin im not that old yet and already make alot of mistakes.

You cant learn unless you make a few mistakes.

vawtman · « **Reply #15 on:** November 05, 2007, 06:36:33 PM »

Im thinking the coils wont be encapsulated in resin if my plan works.I could still break it up in sections.

Did you ever see how a Seeley is wound ,Edaddy?

windstuffnow · « **Reply #16 on:** November 05, 2007, 09:08:59 PM »

I really don't think you have to worry about it melting, there is alot of area for cooling... lots! Thats a big wheel!

To be honest, I would try a group of coils without a backing and calculate how it will do with all the coils in place. If it seems a little low maybe try some low tech ideas and work toward the rotating back plate. I can't imagine each coil will have much more than 10-12 turns, this will keep them thin and close to the magnets so you may not need the backing. Experiment a bit with a test coil you might be surprised...

.

electrondady1 · « **Reply #17 on:** November 06, 2007, 06:16:19 AM »

no, and i can't find it with google .

have you got a link?

vawtman · « **Reply #18 on:** November 06, 2007, 05:06:22 PM »

Heres a link to what it looks like from Oz.

http://www.otherpower.com/images/scimages/5171/seely.html

Mine would be inside out from this obviosly and different supports but the coils wouldnt need to be encapsulated.

The picks really blow up for some reason.

electrondady1 · « **Reply #19 on:** November 06, 2007, 05:49:48 PM »

i like it .

and you wont need the steel wire if you go with a second rotor.

what material will you use for the support.?

vawtman · « **Reply #20 on:** November 06, 2007, 06:28:18 PM »

The problem with the Seeley has i see it is that the steel wire you see isnt insulated.Why Oz had problems.

What material will you use for the support?

I think simply fiber reinforced plywood laminates with maybe dowels.I know it sounds stupid.

The main shaft would need a flange type bearing with outer supports for the stator.

Could test aircore like Ed mentioned also.

Radial alts for vawts is worth a try unless you gearup.

Told you im nuts but so is Ron.Two nuts can work wonders.LOL

wdyasq · « **Reply #21 on:** November 06, 2007, 07:18:28 PM »

Ron Who?

Ron

dinges · « **Reply #22 on:** November 07, 2007, 12:54:46 AM »

My mother taught me not to ask questions I knew the answer too. She also told me not to pretend to be dumber than I was.

If you forgot your last name - check your ID.

You're welcome - Always glad to be of assistance - no need to thank me.

Peter.

vawtman · « **Reply #23 on:** November 10, 2007, 03:26:31 PM »

Hmmm,

Just thought of something since the outer band will rotate with the rotor i could make it in sections and be able to adjust the gap to the turbine.Ive got a plan for the brackets i think.

Pays not to rush into things sometimes.

electrondady1 · « **Reply #24 on:** November 11, 2007, 07:59:42 AM »

depending on how much effort you want to go through it might be possible to have

an individual return path for each pole .

i m thinking along the lines of a threaded steel rod (or two) projecting horizontaly outward from the rotor and holding a steel pad acting as a flux path.

it would be possible to adjust the clearance for the stator.

as well, if at some later time you need to add to the output you could open up the gap and add a magnet to each individual pad .

for that matter ,you could make every coil individually adjustable if you want.

although, with overlapping coils it might be kind of impossible.

i guess the thing is, if your generator is at ground level ,

or even in your basement like you have spoken of,

you are not confined to making a devise with the same limitations as a hawt alt.

vawtman · « **Reply #25 on:** November 11, 2007, 08:45:19 AM »

Now were cookin Edaddy

I was thinkin of a u shaped bracket.

Thanks

skipinder · « **Reply #26 on:** March 28, 2008, 03:21:20 AM »

I thought the steel backing had to all join up for the flux path? I read somewhere that the flux comes from the magnet, passes through the coil into the steel backing, meets up with the flux from magnets left and right. Or have I the wrong end of the stick?

electrondady1 · « **Reply #27 on:** April 19, 2008, 06:19:01 AM »

this is what i had in mind.

ll

n-----ll-----n

ll

the magnets would be placed on the inside of the n's

the flux would have a return path from one mag, over the top to the other mag.

wdesilvey · « **Reply #28 on:** July 03, 2008, 06:21:18 AM »

What is that stator made of??

And, type of wire/ # of turns/coil??

Thanks,

Bill

vawtman · « **Reply #29 on:** July 03, 2008, 01:48:39 PM »

Hi Bill

I'm not far enough along yet to run a test coil.The stator will be simular to the axials seen here only thinner with more coils.

Waiting for bearings for the new shaft.

I spend a good deal of time pacing around it now.It will be kinda"out there".

Everytime i get stressed out with work stuff i think about it.Great medication.

Shoot me a mail if any more ?s since this is old.

Mark

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Author Topic: Radial Alt Thoughts (Read 3170 times)