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Pid current controller

  1. May 24, 2013 #1
    can we control the pulsed current flowing through a laser diode using PID controller???
  2. jcsd
  3. May 24, 2013 #2
    Depends on what you mean by a PID Controller - if you mean a specific device, then probably not, they are not in general able to handle a pulsed feedback, if you are using a current measurement as a feedback element. Thay also do not typically have the frequency response needed. The feedback can be filtered - but then you are typically distorting the signal... However, a PID control scheme - implemented in a uController would work well, if properly designed. The critical design factor will be how fast do you need the control to be?
  4. May 25, 2013 #3
    Although, I won't disagree completely with Wind, depending on the application the answer to your question is yes. PIDs often are aimed at controlling pulsed inputs/outputs. However, I think what you want, if I'm understanding correctly, is a driver. If this is a homework question then please move your post to the approiate discussion venue.
  5. May 27, 2013 #4
    thank u windadct n introyble..

    i want to control the current flowing through a laser diode., for this i am planning to write the code in vhdl for using it in FPGA...

    so my problem here is..
    is it quite necessary to find the transfer function for the system??
    or any other method is there???
  6. May 30, 2013 #5
    If you are using a FPGA then you are using discrete control. Discrete control systems can use PID type control, but sometimes (at least in the case of a Microchip Pic controlled line following robot buggy) we found that Bang-Bang control was the better option! In terms of knowing the transfer model of the function it can help with the control - and could prove beneficial if you want to do some PID tuning... You might be interested in reading about Kalman Filters & this PID controlled espresso machine is pretty cool! http://www.kickstarter.com/projects/zpmespresso/pid-controlled-espresso-machine
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