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High amp motor controler — Parallax Forums

High amp motor controler

bennettdanbennettdan Posts: 614
edited 2005-10-11 15:47 in General Discussion
I have a project that needs a very high amp output DC motor controller. I plan to use IGBT moduals from Powerex the particular one is a 600v 600A modual. I have a nice curcuit for opto isolation and driving of the IGBT modual but I have not worked with the PWM function much and need a little help. I need the frequency to be 15khz or 25Khz·but I dont know how to acompish this with the PWM function. I plan to use a Pot as an input for the speed control. This controller is going to control my electric converted fullsize chevy truck. I have 2 144vdc motors that can handle up to 600A each for short periods at a time. Thanks for any help.

Comments

  • PJMontyPJMonty Posts: 983
    edited 2005-10-10 23:21
    Bennettdan,

    Just a word of caution - if you're unclear on the use of the PWM function, you should definitely hook up something smaller, cheaper, and less dangerous than a 600A motor controller driving a Chevy truck to do your tests. Remember, any sort of bug in your code that causes the PWM to stop and you have a 50/50 chance that your motor is going to be stuck at completely off or completely on.

    I would recommend buying or building a small H-Bridge circuit and small motor to first familiarize yourself with the the way PWM works, and also to test and debug your code. After that, go ahead and control your truck.
      Thanks, PeterM

    PS - You might want to edit this message to change the topic from "High amp motor controller" to "PWM question using Sx/B", or something like that. The current topic might not attract the right people to answer your question.
  • bennettdanbennettdan Posts: 614
    edited 2005-10-11 01:14
    I have a smaller motor setup running with a 555 timer as the PWM input to the controller curcuit . I want to be able to control this with a digital pot or take out the 555 and run off the Sx or Basic stamp. I want to see which one provides the best control. I just have not yet got how to figure the frequency of the stamp to run it directly into my IGBT curcuit. Thanks for the insight.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-10-11 15:47
    The 555 makes a beautiful PWM source under direct analog control. You just turn a pot to get your motion.

    I believe that once you get into digitally generated PWM, the analog control becomes another layer of circuitry and complexity. It adds to your chances for failure and increases thae amount of sloppiness in the system.

    The digital PWM allows you to do things like 'ramp' the input up over a period of time and to have logic set limits to movement and direction.

    I suspect you should just stay with an all digital proto-type.· You could use radio control model airplane or model auto transmitter and reciever.· The reciever would input to the Stamp and general a conversion.

    Whatever you do with that Chevy Truck, put a big red, easy to reach 'Kill' button on the front bumper center until you have it all figured out. That kill button should include engaging the brakes.· Maybe a second push would release the brakes.· You may be the one that is standing in front of it when Murphy's Law comes to visit.

    Design your safety systems first.· We like to hear success stories.

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    G. Herzog in Taiwan

    Post Edited (Kramer) : 10/11/2005 3:53:33 PM GMT
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