Alternative Power sources - Small 3 phase AC motor?

Author

Small 3 phase AC motor?

BobG

2008-03-14, 8:25 pm

Anyone know of a small 3 phase AC motor? Maybe 12V? For
experimentation with controller algorithms? Maybe a way to rewind a
universal motor? (except how do you convert the commutator to slip
rings?)

Vaughn Simon

2008-03-14, 8:25 pm

"BobG" <bobgardner@aol.com> wrote in message
news:98ce1cfe-5e82-4e97-81d4-c2799511a31b@m36g2000hse.googlegroups.com...
> Anyone know of a small 3 phase AC motor? Maybe 12V? For
> experimentation with controller algorithms? Maybe a way to rewind a
> universal motor? (except how do you convert the commutator to slip
> rings?)

A little better explanation of exactly what you want to accomplish will
probably lead to a more useful answer, but for now you need to be looking into
stepper motors and servo motors. There are also chips out there specifically
designed to drive those motors. Once you have a better idea what you are
looking for, check out some of the surplus houses such as Marlin P. Jones
http://www.mpja.com/ .

Vaughn

BobG

2008-03-15, 1:25 pm

Lets say I want to make a 3 phase variable speed drive. Most of these
motors are 6+ HP and use 240V and cost a couple hundred bux and you'll
get killed or go broke while trying to get your software controlled
speed control debugged. Now if I could put the shrink ray on that bad
boy and take him down to 12V all around, I wouldnt be afraid to hook
an avr and three half bridges to it and start programming. Compri?

clare at snyder dot ontario dot canada

2008-03-15, 5:25 pm

On Sat, 15 Mar 2008 07:59:14 -0700 (PDT), BobG <bobgardner@aol.com>
wrote:

>Lets say I want to make a 3 phase variable speed drive. Most of these
>motors are 6+ HP and use 240V and cost a couple hundred bux and you'll
>get killed or go broke while trying to get your software controlled
>speed control debugged. Now if I could put the shrink ray on that bad
>boy and take him down to 12V all around, I wouldnt be afraid to hook
>an avr and three half bridges to it and start programming. Compri?

Make one from an automotive alternator - it is a 3 phase motor inside,
with electromagnet core instead of being an induction motor.

--
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Ulysses

2008-03-15, 5:25 pm

<clare at snyder dot ontario dot canada> wrote in message
news:uk9ot35oddevtpjkhb27hgl2lr7c1lsdef@4ax.com...
> On Sat, 15 Mar 2008 07:59:14 -0700 (PDT), BobG <bobgardner@aol.com>
> wrote:
>
>
> Make one from an automotive alternator - it is a 3 phase motor inside,
> with electromagnet core instead of being an induction motor.

Bingo. Let's see, you'd probably have to eliminate the diodes that keep it
from draining the battery when it's not charging...

>
> --
> Posted via a free Usenet account from http://www.teranews.com
>

Vaughn Simon

2008-03-15, 8:25 pm

"Ulysses" <eatmyspam@spamola.com/> wrote in message
news:13toho5kqrn7j10@corp.supernews.com...
>
> <clare at snyder dot ontario dot canada> wrote in message
> news:uk9ot35oddevtpjkhb27hgl2lr7c1lsdef@4ax.com...
>
> Bingo. Let's see, you'd probably have to eliminate the diodes that keep it
> from draining the battery when it's not charging...

The diodes in an alternator do a bit more than that, they are also form a
full-wave 3-phase rectifier. You may also need to remove a regulator.

Vaughn

Martin Riddle

2008-03-15, 8:25 pm

"BobG" <bobgardner@aol.com> wrote in message news:93b07c2b-db87-429f-8be3-477a4c3ba54f@b64g2000hsa.googlegroups.com...
> Lets say I want to make a 3 phase variable speed drive. Most of these
> motors are 6+ HP and use 240V and cost a couple hundred bux and you'll
> get killed or go broke while trying to get your software controlled
> speed control debugged. Now if I could put the shrink ray on that bad
> boy and take him down to 12V all around, I wouldnt be afraid to hook
> an avr and three half bridges to it and start programming. Compri?

Use 1 ohm 25W ceramic resisters in series with the motor windings. They make for good fuses...

Cheers

clare at snyder dot ontario dot canada

2008-03-16, 3:25 am

On Sat, 15 Mar 2008 23:06:56 GMT, "Vaughn Simon"
<vaughnsimonHATESSPAM@att.FAKE.net> wrote:

>
>"Ulysses" <eatmyspam@spamola.com/> wrote in message
>news:13toho5kqrn7j10@corp.supernews.com...
>
> The diodes in an alternator do a bit more than that, they are also form a
>full-wave 3-phase rectifier. You may also need to remove a regulator.
>
>Vaughn
>
Remove the diodes. Doesn't matter what they do using it as an
alternator, they are superfluous in a motor and will make it so it
won't work.
Many alternators have no regulator built in - particularly those best
suited to using as a motor (like the large frame Mopar or early
Delcotron. The larger the rotor diameter the more torque the "motor"
will produce.

Should be good for about 36 volts 3 phase AC with the feild somewhere
around 6-18 volts DC. Or make a PM feild like the wind charger guys
use.

--
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BobG

2008-03-16, 1:26 pm

I have heard that alternators make crappy motors because the air gaps
are too big and sloppy. Thats why efficient alternators are more
expensive. Besides that, what I'm looking for is a 'scaled down' in
size motor... maybe you cant build a 60Hz motor in a small size even
with a small power because of L or cross section of iron requirements?
OK, run it from 400Hz AC. I just want to know how they work at 60Hz,
and how to control the speed of them. (What I really want to know is
why AC propulsion puts AC induction motors in battery driven cars. Its
either because he's an expert in AC motors, so every problem gets that
solution, or he's on to something he aint talking about. Wonder what
it is?)

clare at snyder dot ontario dot canada

2008-03-16, 1:26 pm

On Sun, 16 Mar 2008 08:15:29 -0700 (PDT), BobG <bobgardner@aol.com>
wrote:

>I have heard that alternators make crappy motors because the air gaps
>are too big and sloppy. Thats why efficient alternators are more
>expensive. Besides that, what I'm looking for is a 'scaled down' in
>size motor... maybe you cant build a 60Hz motor in a small size even
>with a small power because of L or cross section of iron requirements?
>OK, run it from 400Hz AC. I just want to know how they work at 60Hz,
>and how to control the speed of them. (What I really want to know is
>why AC propulsion puts AC induction motors in battery driven cars. Its
>either because he's an expert in AC motors, so every problem gets that
>solution, or he's on to something he aint talking about. Wonder what
>it is?)

AC 3 phase motors have better speed regulation and if you are using a
chopper anyway, going 3 phase AC is not much more complex than PWM DC.
Also gets rid of brushes and commutators and the complexities of
reversing contactors etc. Solid state controllers can vary the
frequency in response to load, matching the power to speed and
acceleration demands.

You can put higher current lower voltage in for higher torque at low
speeds without drawing higher battery current. All around much more
flexible system

--
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BobG

2008-03-16, 5:25 pm

You seem to know what you are talking about, but you get zero
credibility for not using your real name, and for not even using a
stupid handle. What do your coworkers call you? 'Here comes ol _ again'

Vaughn Simon

2008-03-16, 5:25 pm

"BobG" <bobgardner@aol.com> wrote in message
news:29fb9eb5-6c46-4b3f-9a52-1d548387d321@p73g2000hsd.googlegroups.com...
> You seem to know what you are talking about, but you get zero
> credibility for not using your real name, and for not even using a
> stupid handle.

Huh? He is "Claire", and has been so for years. What more do you need?

Vaughn

clare at snyder dot ontario dot canada

2008-03-16, 5:25 pm

On Sun, 16 Mar 2008 12:28:23 -0700 (PDT), BobG <bobgardner@aol.com>
wrote:

>You seem to know what you are talking about, but you get zero
>credibility for not using your real name, and for not even using a
>stupid handle. What do your coworkers call you? 'Here comes ol _ again'

Who you talking to?
My name is there if you look hard enough.

--
Posted via a free Usenet account from http://www.teranews.com

clare at snyder dot ontario dot canada

2008-03-16, 5:25 pm

On Sun, 16 Mar 2008 19:54:34 GMT, "Vaughn Simon"
<vaughnsimonHATESSPAM@att.FAKE.net> wrote:

>
>"BobG" <bobgardner@aol.com> wrote in message
>news:29fb9eb5-6c46-4b3f-9a52-1d548387d321@p73g2000hsd.googlegroups.com...
>
> Huh? He is "Claire", and has been so for years. What more do you need?
>
>
>Vaughn
>
But no "I" - just plain clare

--
Posted via a free Usenet account from http://www.teranews.com

Gordy

2008-03-16, 5:25 pm

BobG

2008-03-16, 5:25 pm

On Mar 16, 5:08=EF=BF=BDpm, "Gordy" <gordon.park...@tesco.net> wrote:
> The latest thing in electric model aeroplanes is the "brushless motor", a =
3
> phase motor run from a smart speed controller at lowish voltage.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Noted... thank you..... but these use permanent magnets... so I
suppose you could learn a great deal about BLDC motors, but not be
able to hook up a compressor in your buddie's garage. Is the 3 phase
motor like a universal motor? Does the field reverse 60 times a sec?
Can you control torque by controlling the field like in a dc motor?

BobG

2008-03-16, 5:25 pm

On Mar 16, 3:54=EF=BF=BDpm, "Vaughn Simon" > =EF=BF=BD =EF=BF=BDHuh? =EF=BF=
=BDHe is "Claire", and has
been so for years. =EF=BF=BDWhat more do you need?
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Sorry. He is 'underbar' as far as I can see. Always thought anything
worth saying was worth attaching one's John Hancock to.
This pedophilia crap could be cured in a week if handles and aliases
werent allowed on bulletin boards. Just the opinion of a crochety old
50+ geezer. Your view of the world might be more rosy.

NotBob

2008-03-16, 5:25 pm

In <ca8fd874-135c-4889-b745-c2e7543348d7@13g2000hsb.googlegroups.com>,
on Sun, 16 Mar 2008 14:44:24 -0700 (PDT), BobG, bobgardner@aol.com wrote:
> On Mar 16, 3:54�pm, "Vaughn Simon" > � �Huh? �He is "Claire", and has
> been so for years. �What more do you need?
>==================================================
> Sorry. He is 'underbar' as far as I can see.

That's cause you're using an idiotic interface to
usenet. Get a real newsreader, and you can plainly
see his name.

> Always thought anything
> worth saying was worth attaching one's John Hancock to.

His is name is attached. Just look at the From:
header.

> This pedophilia crap could be cured in a week if handles and aliases
> werent allowed on bulletin boards.

This isn't a bulletin board. It's a newsgroup which
is propagated via usenet.

> Just the opinion of a crochety old
> 50+ geezer. Your view of the world might be more rosy.

If you used Usenet tools to read and write to Usenet,
your view of the world would be more correct. Only
idiots use web tools to interact with usenet.

jan siepelstad

2008-03-16, 5:25 pm

"BobG" <bobgardner@aol.com> wrote in message
news:93b07c2b-db87-429f-8be3-477a4c3ba54f@b64g2000hsa.googlegroups.com...
> Lets say I want to make a 3 phase variable speed drive. Most of these
> motors are 6+ HP and use 240V and cost a couple hundred bux and you'll
> get killed or go broke while trying to get your software controlled
> speed control debugged. Now if I could put the shrink ray on that bad
> boy and take him down to 12V all around, I wouldnt be afraid to hook
> an avr and three half bridges to it and start programming. Compri?

Why don't you use a small 110 V squirrel cage motor combined withe step-up
transformer (from 12 V AC to 110V AC)?

clare at snyder dot ontario dot canada

2008-03-16, 8:25 pm

On Sun, 16 Mar 2008 14:38:59 -0700 (PDT), BobG <bobgardner@aol.com>
wrote:

>On Mar 16, 5:08?pm, "Gordy" <gordon.park...@tesco.net> wrote:
>=======================================================
>Noted... thank you..... but these use permanent magnets... so I
>suppose you could learn a great deal about BLDC motors, but not be
>able to hook up a compressor in your buddie's garage. Is the 3 phase
>motor like a universal motor? Does the field reverse 60 times a sec?
>Can you control torque by controlling the field like in a dc motor?

Nothing like a universal motor, and can be electromagnet feild,
permanent magnet feild, or more commonly, an induction motor.
Feild current and or stator current can be varied to change torque as
the speed is almost totally iundependent of either. Speed is strictly
a function of frequency.
With three phases, you "chase the rabbit". One phase energizes, then
the next, then the next, and back to #1. Reversing any 2 connections
reverses the order of the windings, reversing the motor. The motors
are self starting, but with less starting torque than a dc series
motor.
And 3 p[hase is not the limit- there can be more phases - hense the
polyphase name.
There are polyphase AC and polyphase DC motors too, just to throw
another wrinkle into the works.
polyphase DC motors can have permag or DC electromagnet feilds
(rotors) while AC 3 phase almost exclusively are induction motors.
Polyphase motors can also be complex multi-pole devices - the more
poles the slower the speed at a given frequency. Most DC stepper
motors are technically polyphase DC motors.
Variable speed 3 phase motors run variable frequency.Most run higher
than 60 htz, particularly propulsion motors.

--
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clare at snyder dot ontario dot canada

2008-03-16, 8:25 pm

On Sun, 16 Mar 2008 23:12:30 +0100, "jan siepelstad"
<jan@microsoft.com> wrote:

>
>"BobG" <bobgardner@aol.com> wrote in message
>news:93b07c2b-db87-429f-8be3-477a4c3ba54f@b64g2000hsa.googlegroups.com...
>
>Why don't you use a small 110 V squirrel cage motor combined withe step-up
>transformer (from 12 V AC to 110V AC)?
>
likely because the squirrel cage motor is not polyphase and will not
duplicate the speed control of a variable frequency polyphase drive.

--
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andre_54005@yahoo.com

2008-03-17, 5:25 pm

You can get 3PH coolant pumps down to about 1/8 HP at places like
McMaster and MSC, cost around $130
Should not be much of a problem to rewind one, even by hand for any
voltage you want.
And being a pump gives you an easy way to load the motor and a measure
of work being done.

Andre' B.

BobG

2008-03-17, 9:25 pm

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