Homebuilt handmade "3 phase" electric motor

[mackrackit]

You need something magnetic between the copper on the rotor. Think of the rotor as a shorted transformer. The copper rings and bars are the short.

Wiki should have said the idea is to induce a magnetic field, not current.

Think of putting a nail on a magnet and the nail will then be able once the magnet is removed, to pick up a paper clip. The nail will also have a N and S pole. Rotate the magnet and the nail will try to move (compass). The rotating field of the stator is doing the same thing to the laminates on the rotor. All the copper is doing is causing a short.

There are several theories for the shorting, The one I feel is correct is to create an insulation between the magnetic parts of the rotor.

Having the electro/mechanical part of the rotor on a twist does help starting as the magnetic parts will cross phase ( in two fields at the same time ) .

Over lapping the stator coils will also make a difference but what you have should move. (spin start? maybe) The bare metal in the stator coils should be facing the rotor, like you had in the first place.

Look at this http://ww1.microchip.com/downloads/e...tes/00887a.pdf

If this does not help, I have a friend who owns a re-wind shop. I will get his input.

[skimask]

You need something magnetic between the copper on the rotor. Think of the rotor as a shorted transformer. The copper rings and bars are the short.

So, you're saying, if I were to lay the rotor out flat, it would go: copper wire (shorted to every other piece of copper wire), insulator, slab of something magnetic-able, insulator, another copper wire, etc.etc. I'll give that a shot...

Wiki should have said the idea is to induce a magnetic field, not current.

It did...but it said inducing a current is basically a side effect of the magnetic field. Same thing but different...

Having the electro/mechanical part of the rotor on a twist does help starting as the magnetic parts will cross phase ( in two fields at the same time ) . Over lapping the stator coils will also make a difference but what you have should move. (spin start? maybe) The bare metal in the stator coils should be facing the rotor, like you had in the first place.

Overlap - I've tried a few different angles so far, even angling the stators the opposite way to the rotor angles...
Spin start - no joy...
Bare metal - that's what I thought...and I've put it back that way.

I just wanna see this thing spin so I can giggle like a little 12 year old...

[mackrackit]

So, you're saying, if I were to lay the rotor out flat, it would go: copper wire (shorted to every other piece of copper wire), insulator, slab of something magnetic-able, insulator, another copper wire, etc.etc. I'll give that a shot...

Yep, but you will not need the insulator. The current created and suppressed in the copper is the magnetic insulator.

It did...but it said inducing a current is basically a side effect of the magnetic field. Same thing but different...

OK, must have been a different article, looked it up on wiki to see where you were coming from. Chicken or egg, which came first?

Overlap - I've tried a few different angles so far, even angling the stators the opposite way to the rotor angles...
Spin start - no joy...
Bare metal - that's what I thought...and I've put it back that way.

Not sure about the spin start, never seen one with straight coils. You could add a start sequence to the code like a stepper if needed.
Attached is a bad drawing of what I mean.

I just wanna see this thing spin so I can giggle like a little 12 year old...

Always nice to do something for fun, and not have a dead line.

[mackrackit]

Might be able to use welding rod between the copper on the rotor. Flux not included

[skimask]

Yep, but you will not need the insulator. The current created and suppressed in the copper is the magnetic insulator.

I meant that in terms of electrical insulator, like a thin piece of plastic or something.

Attached is a bad drawing of what I mean.

Yep, that's what it looks like, roughly...same idea all around.

I wonder, if and when I get this thing going, how much power I'll be able to pull out of it.
Rebuild it, put a bigger shaft in it, beefier wiring, bigger copper, and so on and son on...
I wonder what the limit would be...on a beer budget anyways...

[mackrackit]

Well ,on a beer budget the aluminum could be used in place of the copper

Really, I do not think there is a limit. Time maybe. I have been working on a 1KW wind machine for awhile now. Permanent neo magnets, quad disk rotors 3 phase each, 6 foot turbine.

Get a little money, get a little time...

[skimask]

Do I even have my nomenclature correct for this type of motor?
Is what I'm trying to build really a 3 phase AC synchronous motor?
Or is it really an induction motor with 3 driving phases?
I did some more reading and it almost seems like an actual 3 phase AC synchronous motor has a powered rotor, with the 3 phases on the rotor and the 3 phases on the stator out of phase, and it's that out of phase that makes it turn.
And I'm still trying to get my head around how that 'shorted rotor' with all of its 'shorted' copper bars and wires actually generate that 'counter balancing magnetic force'... Got my left hand out with the 3 fingers pointing every which way...maybe I should use my right hand?

[mackrackit]

Do I even have my nomenclature correct for this type of motor?
Yes and No

Is what I'm trying to build really a 3 phase AC synchronous motor?
No, You are building an Asynchronous motor. Synchronous motors need to be spin started to bring then up to sync speed. The starting motor is called a "pony" motor. Or a wound rotor can be used. These are not common because of the cost to build and the controls needed.

Or is it really an induction motor with 3 driving phases?
Yes, Because a EMF in induced at the rotor. In the US we speak of single and three phase, but what about two? This is what adds to the confusion. I would guess your water heater runs with two 120 volt legs, ths is really two phase. Look at vector diagrams for "delta" and "star" sometimes called "Y" to get a visual on it.

I did some more reading and it almost seems like an actual 3 phase AC synchronous motor has a powered rotor, with the 3 phases on the rotor and the 3 phases on the stator out of phase, and it's that out of phase that makes it turn.
Yes, see above.

And I'm still trying to get my head around how that 'shorted rotor' with all of its 'shorted' copper bars and wires actually generate that 'counter balancing magnetic force'... Got my left hand out with the 3 fingers pointing every which way...maybe I should use my right hand?
You may have to take your shoes off for this one one hand will not work

I scaned a few pages from one of my books "Electrical Circuits and Machinery Volume 2 Alternating Currents" Copyright 1942.

I hope you will be able to read it as the pages are getting somewhat on the yellow side.

Again there are two ways of looking at this. Both using the "shorted" idea.

1- Because of the multiple shorted circuits a large current is produced on the rotor, giving a large magnetic flux. This causing the iron between the copper to become a magnet.

2- If an iron bar is placed in a magnetic field it will take on the prperties of the magnet with one end being "N" and the other being "S". If the maget is rotated the iron bar will rotate too. The large current between the iron bars on the rotor act as a shield so each piece of iron has properties independant of the other.

Visualize the setup from the end with four poles . Every 90 degrees around the stator at any point in time there will be N,S,N,S. Looking at the rotor as a whole, an inductor with multiple high current shorts.

The thing with 3 phase and 120 degress between each phase mahes a rotating field with lets say very small gaps. You might think of a stepper motor setup with very small steps.

Single and two phase motors need an extra winding to start to "throw things out of phase" and some times to keep things out of phase. ( built in phase converters ) Start caps and run caps are sometime hooked here.

I hope I am not making this more confusing.