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Motor Control Question — Parallax Forums

Motor Control Question

CurdZechmeisterCurdZechmeister Posts: 3
edited 2010-01-21 07:21 in Propeller 1
Hello fellow Parallaxians,

I have been scratching my head on how to control the following motor using Parallax components. Please see the pictures below for motor details. Any ideas?

Thank You!
IMG_7457.jpg
1280 x 851 - 169K
IMG_7461.jpg
1280 x 851 - 180K

Comments

  • Bill HenningBill Henning Posts: 6,445
    edited 2010-01-18 20:38
    That is a very unusual motor. A quick google search found nothing interesting.

    Looking at the drawing on it, I'd almost think it was a three coil stepper, but the disparate voltages give me pause.

    I'd try tying green to red/black, and treating it like a bipolar stepper motor, and try driving it with 18V or so.

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  • LeonLeon Posts: 7,620
    edited 2010-01-18 20:49
    It's a standard 400 Hz AC servo motor. Controlling it with a Propeller won't be easy, I'd use a dsPIC.

    Leon

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  • CurdZechmeisterCurdZechmeister Posts: 3
    edited 2010-01-18 21:04
    Bill, Leon ... thank you so much for your feedback! Yes, I figured that driving the motor with the Propeller would be somewhat complicated. Actually, I didn't get anywhere when I tried. I will take a closer look at a dsPIC as Leon suggested.

    Thanks again!
  • LeonLeon Posts: 7,620
    edited 2010-01-18 23:29
    You will need a 400 Hz power source. of course. They are rather expensive.

    Leon

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  • kwinnkwinn Posts: 8,697
    edited 2010-01-19 02:08
    Is this not the kind of thing the prop excels at? Use an H bridge and pasm or counters to generate 400Hz signals.
  • Bill HenningBill Henning Posts: 6,445
    edited 2010-01-19 03:36
    You are most welcome... but I think it would be a LOT cheaper to simply use a regular DC stepper motor, gear motor, or servo [noparse]:)[/noparse]
    CurdZechmeister said...
    Bill, Leon ... thank you so much for your feedback! Yes, I figured that driving the motor with the Propeller would be somewhat complicated. Actually, I didn't get anywhere when I tried. I will take a closer look at a dsPIC as Leon suggested.

    Thanks again!
    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.mikronauts.com E-mail: mikronauts _at_ gmail _dot_ com 5.0" VGA LCD in stock!
    Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
    Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
    Las - Large model assembler Largos - upcoming nano operating system
  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2010-01-19 09:31
    Nice looking pics of the motor. BTW, where did you pull the motor from? I was thinking it might be another clue for what kind of motor is, but it sounds like Leon may have the answer for you.

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  • LeonLeon Posts: 7,620
    edited 2010-01-19 09:58
    kwinn said...
    Is this not the kind of thing the prop excels at? Use an H bridge and pasm or counters to generate 400Hz signals.

    Look up AC servos. There is a lot more to it than using an H-bridge and some simple software.

    Leon

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    Post Edited (Leon) : 1/19/2010 10:03:07 AM GMT
  • CurdZechmeisterCurdZechmeister Posts: 3
    edited 2010-01-21 03:59
    Thanks for the many responses to the pictures above, i really appreciate it. The motor is part of an aircraft instrument, hence the 400Hz and because of the odd form factor of the motor I have not been able to put a regular DC motor/stepper into its place. Creating the 400Hz signal is not overly complicated, I was able to do that simply by pulling some PWM stuff together. However, getting the motor to run smooth is another complication that I ran into. Thanks for the idea with he H-bridge(s), that would work, but it's somewhat tricky to get the right torque on the motor. So I flipped through AN822 and AN892 and AN907 from Microchip and found some helpful stuff in there.

    I will post more as I find out more about the behavior of the motor. Thanks again everybody! Love the forum by the way.

    Curd.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-01-21 07:21
    Aircraft use 400Hz so that they can reduce the iron mass, so keep the frequency about right. If you reduce the freq the losses get higher and it will overheat, too high a freq and it would probably give reduced output.

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