3 Phase PWM with PIC Help!!

Discussion in 'Embedded Systems and Microcontrollers' started by Shreder001, Jun 15, 2009.

  1. Shreder001

    Thread Starter Member

    Mar 7, 2009
    22
    0
    Hey guys, I am beginig to make a three phase motor controller for my RC car with a dsPIC30F5015 microcontroller and I have a few questions, Im quite new at programming. Also, I need at least 256 Bytes of EEPROM, and I was wondering if there was any other PIC more suited for my application.
    1. I looked at the datasheet for it and I found a mode called
    "Complementary PWM Operation"; found here on page 100: http://ww1.microchip.com/downloads/en/DeviceDoc/70149D.pdf
    , what does this mean? My interpritation was that it creates PWM
    signals on the PWM pins that can power my three phase motor.
    2. Is there a common method for approaching three phase generation on the PIC?

    Thanks a Ton!!!!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Are you sure you have a three phase motor? Most RC car motors are permanent magnet DC types that are well suited to PWM speed control.
     
  3. Shreder001

    Thread Starter Member

    Mar 7, 2009
    22
    0
    Yeah im sure. I forgot to mention that it is a sensorless motor. Most high speed after market rc cars have sensorless brushless 3 phase motors.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The PIC is really for DSP, so not really suited to the usage.

    What specific motor are you using.
     
  5. Shreder001

    Thread Starter Member

    Mar 7, 2009
    22
    0
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Guess I'll have to take your word for it - the site gives zilch worth of useful information about the motors.

    I was always under the impression that brushless DC motors had the DC to AC 3 phase circuitry built in. I would want to verify how those motors are made and controlled.

    If you want to do your own motor controlling, look for a PIC (not a DSP) with at least 3 channels of PWM built in.
     
  7. Shreder001

    Thread Starter Member

    Mar 7, 2009
    22
    0
    Thanks!!!!!!!!!!!!
     
  8. AlexR

    Well-Known Member

    Jan 16, 2008
    735
    54
  9. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    No the typical brushless sensorless R/C motor is just three windings in delta configuration and using permanent magnets for the rotating field. It is really an AC motor and the speed controller does the conversion of battery DC voltage to 3 phase drive to the motor windings. The many commercial R/C brushless motor speed controllers are very competively priced and it would be hard to duplicate their function at less total costs. You drive the controller just as if it were a R/C servo with PPM pulse control.

    Lefty
     
Loading...