How to build and assemble my own stator ring

[StephenD420]

Hello all,

I am currently working on a project that requires a stator ring like the ones found in electric motors where there are 2-3phases of electromagnetic coils placed in a circular fashion with a pole pointing towards the center (look at picture below). The coils would be powered by AC current to make a rotating magnetic field as I do not think DC would create the necessary rotating magnetic field, plus every 2-3 phase motor I have seen on the web has been AC with a 3 phase switch(which I do not know what it is). I am having a hard time finding information on how to build my own stator ring. Like I do not know how to connect each coil to the others in order to make a rotating magnetic field and I cannot find a formula that tells me how many turns I will need to use to create a magnetic field of about 1.5-2 T, which is the strength I need to use since I have to also use neodymium magnets and the magnetic field strength has to be about the same for the project. Since a neodymium magnet is about 1.5-2 T at its surface I need to have about that magnetic field strength using the stator.

I would appreciate any help you guys could give. Are there any websites that show how to build stator rings, how to connect the coils together and shows how many turns of coils needed for a certain magnetic field strength? Are there any books with this information? Are there any stores that I could go to and ask? Any help would be greatly appreciated.

I have googled brushless motors and stator rings, stator coils, etc and all of the information I have found has showed me in what order to connect the windings together but I cannot find information on how the connected windings connect to the 3-phase AC switch or how many turns in each coil I need to create a rotating magnetic field of strength 1.5-2 T as the neodymium magnets that I am also using in my project is about 1.5-2 T at its surface. Would I use the solenoid equation B=u*n*I where n is N/L for each coil of the stator?
I cannot find a formula to tell me how many turns per coil I need for my stator ring to create a 2 T rotating magnetic field. Does anyone know how I can tell how many turns I need?

Also, what three phase automatic switch would work best for a stator ring? In other words, what do I connect the three wires to? Do you guys know of any stator assembly manuals or directions on how to assemble and connect the stator and to tell how many turns are needed.

Any help would be appreciated.

Thank you guys in advance for any help you can provide in my first venture in electrical engineering by creating a rotating magnetic field using a steel stator ring, coils of wire, and a 3-phase ac switch.

Stephen

Picture of a stator ring that I found on the internet, mine will be a steel ring with the 4-6 notches for the coils pointing inwards so the rotating magnetic field will be inside the ring:

[Flux]

You are asking a lot and you will not get all the information you want here.

Machine design of the type you are looking at is fairly complex and well removed from the simple air gap machines you see here as wind turbine alternators.

I take it you are making some form of synchronous motor or brushless motor. Conventional  motors use ac and produce a rotating field at the synchronous speed of the supply. if you don't want to be tied to that then you are probably looking at switched dc as in the case of brushless dc motors. The only variable speed machines that use ac are fed by cycloconverters or variable frequency inverters and are known as VF drives. Although the vf drive is ac it is produced by switching from dc, not a normal ac source.

You should be able to find connection schemes in conventional motor books as the normal polyphase winding does produce a rotating field. Some of the things you are looking at use salient poles such as in the smart drive washing machines, the effect is similar but the winding methods are not the same as normal 3 phase motor windings.

Numbers of turns will depend very much on your layout and conditions and on the complete magnetic circuit.

Iron is fairly saturated at 1.4Tesla so you will struggle to get fields much above this in your air gap.

Machine design is actually quite complex and you will only find hints on the internet unless you happen to hit something where some benevolent person has decided to make his own efforts public. If it is what you need then you can copy it but you would still need considerable knowledge to modify it.

I hope this helps enough to point you in the right direction but you will need to do a lot of resaerch.

Flux

[StephenD420]

All I am making is the stator ring to create a rotating magnetic field. So all I need is to know how to tell how many turns to make the coils with a total of six coils on the stator to get a 1.5 to 2 T magnetic field from the supplied ac current and what is the 3-phase ac switch called that is used to power the stator ring coils, which are at 60 degrees apart from each other, to create a rotating magnetic field. I am not making a very complex or difficult design as you were suggesting. I am really making the stator ring that I saw on you guy's windmill just smaller, where the coiling of the coils go around a loop like the given picture and I just cannot find how many turns or what the needed switch is called so I can buy it.

Thanks for the help.
Stephen

[RP]

where the coiling of the coils go around a loop like the given picture

What picture?

[StephenD420]

I can see the picture...here is the link http://www.spokanister.net/images_web/KTM_Tech/Stat/Stator_Rewind-08.JPG

I really just need to know the formula to deterine the number of turns per coil on a six coil stator ring to get a 1.5-2T rotating magnetic field and what is the 3-phase switch called that the three wires of the six coils connect to. Here is a link to what I am trying to do( The stator assembly at the top): http://www.tpub.com/neets/book5/18b.htm

and this link as well: http://www.wisc-online.com/objects/ViewObject.aspx?ID=IAU11808

Please look at these and please help and advise me on the two parts I am missing.

Thanks
Stephen

[ghurd]

The pic does not show up for us,
and clicking the link gets
"Oops! That didn't work, did it?
You CAN'T view that image from where you are now!
Someone has tried to HOTLINK to my picture.... read on:
Images, Articles, Bookmarks - Legal Stuff....."

Flux said "Iron is fairly saturated at 1.4Tesla so you will struggle to get fields much above this in your air gap."
My personal interpretation of that is I personally would be very lucky to get 1.4T.  And I doubt you will get anywhere near 2T.

I do not quite follow the logic in the following statement, but I have a feeling your perceived problems are related to:
"I will need to use to create a magnetic field of about 1.5-2 T, which is the strength I need to use since I have to also use neodymium magnets and the magnetic field strength has to be about the same for the project. Since a neodymium magnet is about 1.5-2 T at its surface I need to have about that magnetic field strength using the stator."

Seems like a servo motor driver is what you need to power it.

Someone here posted a dual rotor PMA being used as a motor.
I have no idea how to find it.  I think it was in Diaries.
G-

[TomW]

The pic does not show up for us,
and clicking the link gets
"Oops! That didn't work, did it?
You CAN'T view that image from where you are now!
Someone has tried to HOTLINK to my picture.... read on:
Images, Articles, Bookmarks - Legal Stuff....."

Flux said "Iron is fairly saturated at 1.4Tesla so you will struggle to get fields much above this in your air gap."
My personal interpretation of that is I personally would be very lucky to get 1.4T.  And I doubt you will get anywhere near 2T.

I do not quite follow the logic in the following statement, but I have a feeling your perceived problems are related to:
"I will need to use to create a magnetic field of about 1.5-2 T, which is the strength I need to use since I have to also use neodymium magnets and the magnetic field strength has to be about the same for the project. Since a neodymium magnet is about 1.5-2 T at its surface I need to have about that magnetic field strength using the stator."

Seems like a servo motor driver is what you need to power it.

Someone here posted a dual rotor PMA being used as a motor.
I have no idea how to find it.  I think it was in Diaries.
G-

Glen;

Ditto on the dead link.

Now I think it is time for him to cut to the chase and tell us what he is trying to really do rather than his interpretation of what he has to do to get there. Seems a bit unnecessarily mysterious being so vague with no details? We see this a lot and it seems like some folks put a lot of effort into keeping the true goal a secret for some reason?

Many times a straight question will yield data to help. Motor & generator theory is a century old at least so most stuff has been investigated. Maybe not all but a LOT. And, the big point here: Someone who posts here probably has the answer to a straight up question?

Carry on.

There is no spoon!

Tom

[StephenD420]

All right guys...you copy the link and paste in the address bar and it comes right up. Here is the link for the picture of a stator ring that looks similar to what I need to complete for my project: http://www.spokanister.net/images_web/KTM_Tech/Stat/Stator_Rewind-08.JPG

copy this link, paste it in the address bar and hit enter and it comes up.

I am a junior at Georgia Tech and I have to build a stator ring, and only the stator ring, not a motor or anything, just the stator ring. My professor said that iron and is good up to 2T, just like a neodymium,  so that is not wrong and I have that material so dont worry about that, I just need a formula for the number of turns based on any strength of magnetic field the 2T is on the high end but all I need for the project is 1.2-1.5T so the prof said that the steel and iron rings he supplied would do it. All I need to  know is a formula to tell me how many turns since there is obviously 100 turns for every stator ring. And on the second link I gave yall said that I need an AC POWER SUPPLY WHERE ONE WIRE IS CONNECTED TO PHASE A, ONE WIRE TO PHASE B, AND ONE WIRE TO PHASE C, so all I need is an AC switch with six screws, not a motor to power it just AC power. so I figured that out but I still need to know a formula to figure out how many turns for any strength of magnetic field.

I am not trying to build an entire complicated motor here just a stator ring with a rotating magnetic field. And if this is still too vague then I am sorry, this is all the prof has given to the class, so this is enough information. I am not trying to be vague I am a student trying to figure this stuff out and I really do not know how to better make my question more straight up than "is there a formula to determine the number of turns required per coil on a six coil stator ring setup using iron or steel for the ring to create a magnetic field of any strength?" if anyone can give me the formula then I have all i need to complete my project.

Thanks guys.
Stephen

Stephen

[Flux]

In the past there have been empirical formulae published for electromagnets, this is more like what you need but unfortunately they normally work in closed magnetic circuits.

I was never an engineer and I have been out of the electrical industry for 15 years but I still maintain that you might as well not bother with the iron above 1.5T at 2T the permeability slope of iron is reduced to that of air.

Typical values of the highest grade neo available give Br as something like 1.3T. 2T is likely beyond the intrinsic value of the ideal material.

I can't go into this in any more detail but I suspect you should be able to find formulae for the field at the centre of an air cored solenoid, your iron will most likely be sufficient to steer most of the flux in the direction you want so the field ought to be very similar.

If you go back to older information the cgs units used the field at the centre of a coil as a definition of the unit of current ( absolute amp). You should be able to adapt this to MKS units.

If you are going to switch your rotating field then you need dc, if you switch normal frequency ac you will not get what you want and the inductance of the coil will make that flux density impossible.

Sorry to be so negative but the snag with education is that you need to know a great deal to realise that in fact you know very little. Either you are only expected to skim the surface of this or you have misjudged the problems. I hope you find your formula but it may not be too wise to check the accuracy of the results, there are a lot of variables involved in this one. if it gets you in the right ball park that may be good enough.

Flux

[Flux]

Try this link ( first hit in Google)

http://www.utc.edu/Faculty/Tatiana-Allen/magfield.html

That is for an air cored solenoid but up to about 1.4 T the iron will probably keep the flux similar. At much lower fields the iron cored figure will be way higher than the air cored figure. I don't see how you are going to get closer than this without much more details of your iron circuit.

Flux

[StephenD420]

yea I only need to be in the ball park of about 1.2T. so I would use the solenoid equation B = mu*n*I where n = N/L where N is the number of turns and L is the length of the solenoid to find out how many turns for each coil to be 1.2T or do I divide it by 3 so each pair of coils activated as the AC sine wave goes through phase 1,2,3 gets the cumulative magnetic field of 1.2T?

[artv]

Hi Steve............I couldn't get that link to work but the other one .......tpub.com......fantastic site very informative will be reading it for days to come..........thanx very much for the link.........artv