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Best way to Drive Steppers?

Discussion in 'Electronic Basics' started by Peter Kiproff, Apr 11, 2004.

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  1. Is comparator switching, or resistor current limiting better?
    I'm using Maxnc on some home brew stepping motors drivers for lathe & mill
    work.
    I've been satisfied that it works as well as it does however I'm seeing the
    need for more speed/pwr

    My setup is a Fet with a .1 ohm current detect applied to a comparator that
    naturally oscillates @
    approx 1 kHz, I adj the ref so I average 1.4 amp per phase as per mfg
    recommendations.
    My motors are rated 5V @ 1.4A, the raw pwr supply is approx 15 V, I'm
    running half steps.
    There are 4 per Axis X, Y, Z * 4 machines so I would like to modify what I
    have.

    The currant drops of if I try to go faster, so this is my limitation.
    If I was to use say a 10 ohm 25 W resistor on each leg limiting the currant
    to the same 1.4 A

    Is it any better?

    If I put a cap in parallel with each resistor would this improve
    performance? what value?

    Double the drive voltage? any currant derating?

    Thank you for responding
    Peter
     
  2. CFoley1064

    CFoley1064 Guest

    Subject: Best way to Drive Steppers?
    A great tutorial on stepper motors is Jones on Stepping Motors. It's written
    by Doug Jones of the University of Iowa Department of Computer Science.

    http://www.cs.uiowa.edu/~jones/step/

    It's a great newbie intro to the subject.

    There are many ways to increase the power of a stepper motor. A lot of them
    are covered in there.

    Good luck
    Chris
     
  3. John Jardine

    John Jardine Guest

    The added caps offer only limited benefit. (without a lot of work the sizes
    have to be guessed at, anyway)
    However you drive 'em the current always drops off the faster you go.
    As you're using existing motors then the best option is to up the supply
    voltage, (the motors won't be hurt). Keep the same limited 1.4A but use a
    supply of say 30 to 50V. Expect the performance to increase pro-rata with
    the supply voltage. This means big power resistors and heatsinks and a point
    can be reached where it's cheaper to just use a high supply voltage and
    bought-in chopper units.
    regards
    john
     
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