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Stepper motor current rating and number of coils — Parallax Forums

Stepper motor current rating and number of coils

metron9metron9 Posts: 1,100
edited 2009-09-18 06:51 in General Discussion
I am doing some stepper motor drive circuits but I need some help with the current rating.

I am playing with a 10 wire motor that has a rating of 0.75A

After looking at the step pattern for the 5 coils it turns out that 4 coils are on at all times
The steping happens when the off coil is turned on and the previous coil is turned off.

Is the rating assume 4 coils or is it each coil so that a current of 3 amps would be drawn with 4 coils energized for this particular motor?


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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Comments

  • dev/nulldev/null Posts: 381
    edited 2009-09-17 09:14
    The rating is usually pr. coil, so yes 3 amps would be the total you need from a power supply. What kind of motor?

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    Don't worry. Be happy
  • metron9metron9 Posts: 1,100
    edited 2009-09-17 12:54
    It is a VEXTA 5 phase. I have had it sitting in a box for years. Reason i am playing with them is a friend of mine built his onw CNC machine. A few years ago I bought a unipolar stepper motor driver and made a simple linear table for a process we needed in our shop. I went through my garage and cleaned it out after 20 years of junk piling up and now I have a 25 x 30 empty shell to move my "hobby" into. I plan to get a mini mill/lathe from Harbor Freight and add CNC stepper control with Mach3 and then design and build my own CNC for cutting circuit boards and other stuff. I also found 4 computers with parallel ports that still work and one has mach2 on it from the project two years ago. Since they still work I can't just throw them away!

    Back to the motor, I did find some simple driver circuits and my first little project to build is a peristaltic pump I can use for potting epoxy using a stepper motor. I want to use a micro to control the stepper and allow some memory saving buttons to make the pump easy to use for dispensing small amounts of epoxy. I have a bunch of mixer tubes I found as well so I may try doing some doming resin again perhaps make a doming machine since my company makes stickers.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Think Inside the box first and if that doesn't work..
    Re-arrange what's inside the box then...
    Think outside the BOX!
  • Agent420Agent420 Posts: 439
    edited 2009-09-17 13:35
    I like this forum because I learn something new every day ;-)·

    Never really knew about 5 phase steppers before...

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  • metron9metron9 Posts: 1,100
    edited 2009-09-17 13:40
    You can learn alot here on stepping motors.
    http://www.cs.uiowa.edu/~jones/step/software.html

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Think Inside the box first and if that doesn't work..
    Re-arrange what's inside the box then...
    Think outside the BOX!
  • Agent420Agent420 Posts: 439
    edited 2009-09-17 13:42
    ^ That is a great link, I often recommend it to others myself.· Just never really was exposed to 5 coil steppers before...· I thought you might be referring to a servo motor.

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  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-09-17 16:34
    I believe the 5-phase stepper concept was a German innovation and came about for pretty much the same reasons that Mercedes Benz developed a 5-cylinder Diesel engine: smoother torque with less vibration and resonance. This works because the power impulses (phase changes) are more widely distributed over the 360-degree phase circle, rather than occurring together or in direct opposition.

    -Phil
  • metron9metron9 Posts: 1,100
    edited 2009-09-18 06:51
    I still cant after staying up till 2am for two days now get this 10 wire motor to turn. All I can do is make it jostel back and forth.
    I just don't have the correct sequence to step or the motor wiring chart I found is not correct.
    Any help i would very much like.
    Tha actual motor is VEXTA PK564-AA
    The wiring chart i have is attached
    The method I am connecting is here http://dsaprojects.110mb.com/electronics/cnc/cnc_ctrl.html
    I have tried this pattern from here ( I am using a micro not a parallel port) http://www.cs.uiowa.edu/~jones/step/software.html


    ·········· steptab[noparse][[/noparse]0] = 13;· { binary 01101 }
    ·········· steptab[noparse][[/noparse]1] = 9;·· { binary 01001 }
    ·········· steptab[noparse][[/noparse]2] = 11;· { binary 01011 }
    ·········· steptab[noparse][[/noparse]3] = 10;· { binary 01010 }
    ·········· steptab[noparse][[/noparse]4] = 26;· { binary 11010 }
    ·········· steptab[noparse][[/noparse]5] = 18;· { binary 10010 }
    ·········· steptab[noparse][[/noparse]6] = 22;· { binary 10110 }
    ·········· steptab[noparse][[/noparse]7] = 20;· { binary 10100 }
    ·········· steptab[noparse][[/noparse]8] = 21;· { binary 10101 }
    ·········· steptab[noparse][[/noparse]9] = 5;·· { binary 00101 }

    Also this pattern from here http://www.cs.uiowa.edu/~jones/step/types.html

    With a 5-phase motor, there are 10 steps per repeat in the stepping cycle, as shown below: Terminal 1 +++
    +++++
    ++ Terminal 2 --+++++
    +++++--- Terminal 3 +
    +++++
    ++++ Terminal 4 +++++
    +++++
    Terminal 5 ----+++++
    +++++-
    ····time--->>·Also various other patterns but the most forward movement in steps i can get is 3 then I can't find the 4th it always gose one step back.I tried doing it a step at a time (no pun intended) and I just have not been able to even think I was close to getting it right.·HELP!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Think Inside the box first and if that doesn't work..
    Re-arrange what's inside the box then...
    Think outside the BOX!
    motor10.jpg
    576 x 493 - 22K
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