speed control with closed loop

Discussion in 'Embedded Systems and Microcontrollers' started by sudhakar.k, Nov 10, 2011.

  1. sudhakar.k

    Thread Starter New Member

    Nov 10, 2011
    1
    0
    i have made a circuit that controls speed and direction of a pmdc motor using 89s52microcontroller now i need to make it a closed loop can some one help me with the code and circuit..
     
  2. nigelwright7557

    Senior Member

    May 10, 2008
    487
    71
    Look up PID controller.
     
  3. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    what's your choosen method of feedback. It's often much easier to implement a dedicated driver and just provide it the commands.
     
  4. jimkeith

    Active Member

    Oct 26, 2011
    539
    99
    Here is a simple method that is well within the capability of the 8052 microcontroller without advanced peripherals.

    Create an A-D converter for voltage feedback using a V-F converter scaled to: 100kHZ = full speed--I have used the Exar 4151 with good success, but not by using the circuit provided on the spec sheet. The sign bit (direction) is provided by a simple comparator that detects voltage polarity.

    Establish a time base of 10mS--this provides a count of 1000 at full speed for a resolution of 0.1%. Now that may seem excessive resolution, but it is required to make a PI (proportional-Integral) loop work without being lumpy.

    Count the oscillator with an external interrupt.

    This will provide you something to start with--if you choose to go in this direction, I will rough out the V-F circuit for you.

    Post a schem of your present hardware.
     
    Last edited: Nov 10, 2011
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