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Controlling Motor with 0-10V input

Discussion in 'Sensors and Actuators' started by Tim Clark, Oct 22, 2015.

  1. Tim Clark

    Tim Clark

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    Oct 22, 2015
    Hey guys and girls,

    I am trying to complete a project for my senior design class. The task at hand is as follows: I have to control a either brushed or brushless motor with a simple 0-10V input that correlates with the motor speed. The motor is going to be rated at 50A 24V. Currently I am thinking of using an off the shelf motor controller with a built-in PWM(pulse width modulation) unit. However with every component like this it uses a potentiometer (manual component) to alter the duty cycle which in turn alters the motor speed, now I need to do that with a simple electrical input fed from a computer program.

    My thinking was that maybe, somehow I could control the duty cycle with an input voltage, say by just popping the pot off and replacing that input with a 0-10V input, but I'm not sure if that is the correct course of action or not seeing as how I'm guessing the input coming from the potentiometer is most likely the PWM signal which is used control the motor speed.

    Any help is GREATLY appreciated.
     
  2. Bluejets

    Bluejets

    3,453
    698
    Oct 5, 2014
  3. Minder

    Minder

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    Apr 24, 2015
    That is a large motor.
    If the drive in question uses a PWM with simple 555 to control the motor, the pot will just be to vary the timing input so it could be replaced by an Op-amp or maybe with a variable output opto such as H11F1 etc.
    M.
     
    Tim Clark likes this.
  4. Tim Clark

    Tim Clark

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    Oct 22, 2015
    Yes it is, we are trying to simulate air flow from an indy car, to be used in a scale model in a windtunnel in order to analyze the effects it has on aero dynamics.

    The pot on the my motor controller UK1133, is connected to the PIC16F616, which seems to me is operating exactly as you suggested.

    Now if I were to replace the pot with an op-amp or the mosfet IC you suggested, how would I connect it in place of the pot?
     
  5. Minder

    Minder

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    Apr 24, 2015
    I see the controller is Pic based already, I guess the 16F616 you refer to, so I assume they are using a 0-5v pot in to a analogue input.
    So all you should have to do is input a variable signal level between the pic common (gnd) and the pot centre/slider conductor whatever method you are using to produce the variable level.
    M.
     
    Tim Clark likes this.
  6. Tim Clark

    Tim Clark

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    Oct 22, 2015
    Great!

    That's what I was thinking I just haven't dealt with the 16F616 before but I found the datasheet and all I should have to do now is scale down my 0-10V input using a simple voltage divider to get it to 0-5V, and feed that to the PIC, and that should remotely alter the duty cycle.

    Thank You!

    Your help has been invaluable!
     
  7. Tim Clark

    Tim Clark

    5
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    Oct 22, 2015
    One more question, would it be possible to use this approach for a brushless motor, the project just took an unexpected turn and now we have come to the conclusion that a brushed motor will not be able to give us the numbers we need.

    I'm not quite sure how the PID connectors would come in to play using this controller. If i have to get a different controller I will, however it would be more favorable to use the uk1133.

    Thank you again!
     
  8. Alec_t

    Alec_t

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    Jul 7, 2015
    If you use an off-the-shelf controller for the brushless motor it will have a speed control input which might accept PWM or a 0-5V analogue input. Check datasheets for candidate controllers.
     
  9. Tim Clark

    Tim Clark

    5
    0
    Oct 22, 2015
    I see, well based off of this schematic it seems as though there is no such input, unless I'm missing it.

    upload_2015-10-26_19-55-40.jpeg

    If there ends up being no control input for the PID loop, is there a way to basically hot wire the Hall sensors so I can just start the motor up and then continue to control the motor speed simply with the Duty cycle input.

    I tried this with a smaller brush-less motor earlier and it wasn't spinning smoothly, however I'm not sure if this was because of the PID cables being disconnected or not, because all I need is speed control, I have no desire for positional control what so ever.
     
  10. Minder

    Minder

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    586
    Apr 24, 2015
    A BLDC motor requires a controller to handle the three commutation pulses, if you want to use analogue control and simple velocity loop, look for a A-M-C servo drive off ebay.
    Why do you require a BLDC over DC brushed? maximum rpm?
    M.
     
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