Alternator stepper

[smitjs]

I am in need of a couple of power stepper motors for use off 12 volt DC. I have read that car alternators can be rewired for this, but cannot find the details. Any help please?
Surely the current draw of the stator windings will be excessive. Has anybody had some experience with PWM adjustment of the higher currents?
I am thinking of limiting the current to about 3 ampere.
Thank you
smitjs

[TrueNorth]

Google on Don Lancaster, go to his website, and search on "flutterwumper" - his slang for an alternator rewound as a stepper. He mentions a video by John Rees which shows how to rewind alternators to use as steppers. He gives a mailing address for John.

I am not sure how many steps per revolution you could get, or what the positional error per step would be with alternators - both important considerations. (In conventional steppers a 5% error per step is typical, but the errors are non cumulative.)

[Andre' B]

I bet you would have better luck driving an alternator like a brushless DC motor then a stepper motor.

Mesa has a low power driver for BLDC 3 phase that would likly make an alterantor spin, # 7I39 in the motion control page.
http://www.mesanet.com/

[Al_The_Man]

The most efficient would probably driving it in reverse with variable frequency 3ph AC, it would then be a synchronous motor.
Al.

[smitjs]

Thanks guys,
As I am already using a microcontroller on the project, I could then integrate it all for the stepper as well. Generation of 3 phase PWM signals should not be too much of a problem. Perhaps for short period use, one could limit the current draw by connecting the rotor winding in series.
I have found a good article on alternators at
http://islandcastaway.com/stuff/wind...%20Secrets.htm.
That will get me started.
Thanks for the help
smitjs

[Ray Ingersoll]

Originally Posted by TrueNorth Google on Don Lancaster, go to his website, and search on "flutterwumper" - his slang for an alternator rewound as a stepper. He mentions a video by John Rees which shows how to rewind alternators to use as steppers. He gives a mailing address for John. I am not sure how many steps per revolution you could get, or what the positional error per step would be with alternators - both important considerations. (In conventional steppers a 5% error per step is typical, but the errors are non cumulative.)

True North the article you are talking about was a sign router John built the
alternator was a ford the windings are removed it is rewound every third
pole with 28 gauge wire 12 to 15 feet the windings are alternated one wound
left one wound to the right which alternates the poles north south the rotor
covers three poles you can step the rotor around the outside very effectly
lots of torque there is also on youtube how to convert a car alternator into
a stepper motor there are four articles on this you don't have to rewind
the alternator on this one you have to keep your voltage down though
John got 10 steps out of his alternators then geared them down 100 to 1
I believe don't quote me on that it's been a while. have a good one.

Ray Ingersoll