How to simultaneously drive 4 BLDC motors with variable speed?

Discussion in 'The Projects Forum' started by guyfromafar, Apr 16, 2015.

  1. guyfromafar

    Thread Starter New Member

    Oct 9, 2013
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    Hi Guys,

    my first time here and knows basic about motors. How can I simultaneously drive 4 BLDC motors with 3 different RPMs? max is 1.1A @ 7500 rpm, 48vdc input each. thanks. :)
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Insufficient information!:(

    What/how are they being driven both command signal and drive type.
    Is closed loop required?
    Is this a design from scratch scheme?
    Motor plate details/specs?
    Max.
     
  3. guyfromafar

    Thread Starter New Member

    Oct 9, 2013
    6
    0
    Hi Maxheadroom,

    all i have now is just an idea. I am thinking to burn in (cum speed test) 4 motors using a single driver that automatically switches input voltage (to change speed) at a defined time.

    ex: 15mins - x rpm => 15mins - y rpm => 2hrs - z rpm

    my motor is capable of 8500rpm min.
    idea eff speed is 7500rpm
    steady current draw is <1.1A at 7500rpm
    max current draw is <4A at 8500rpm
    shaft total runout is <0.001"
    hall sensor output
    totally enclosed, non-ventilated
    electonic commutation, molded hall sensor
    wound stator with exposed laminations
    rare earth magnets on the rotor
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    As I see it trying to control 4 motors with one drive will be near impossible, especially with what sounds like BLDC type which are electronically comutated by the drive.
    Max.
     
  5. guyfromafar

    Thread Starter New Member

    Oct 9, 2013
    6
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    Hi Max, how about 1 driver for 3 bldc motors at single speed? how would this design look like? just trying to understand what are the limitations. thanks.
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    1,103
    Apart from the Hall sensor output and two main inputs for the 48V supply, does the motor have an input intended for a speed control signal?

    Edit: Can you post a link to the motor?
     
    Last edited: Apr 17, 2015
  7. guyfromafar

    Thread Starter New Member

    Oct 9, 2013
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    sorry alec no link :(

    i may need to dismantle 1 motor to know the wiring. i'm quite sure there is an input for speed control.
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    1,103
    Does the motor have a plate indicating the wiring connections? Wiring colours? Can you post a pic of the motor?
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Normally BLDC motors each have three Hall sensors for commutation, if you want off the shelf drives that can be controlled independently open loop (velocity control) there is A-M-C, Copley Controls, Aerotech to name a few.
    These use ±10vdc to control rpm.
    Max.
     
  10. guyfromafar

    Thread Starter New Member

    Oct 9, 2013
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    ok alec. i'll post a pic once available. thanks.
     
  11. guyfromafar

    Thread Starter New Member

    Oct 9, 2013
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    0
    appreciate, max :)
     
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