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3 phase AC sinewave — Parallax Forums

3 phase AC sinewave

TumblerTumbler Posts: 323
edited 2013-03-27 04:06 in General Discussion
Hello,

I need one with adjustable frequenty (0 - 500 Hz, 3-10V)
Can someone push me in de right direction? I don't know where to start.

Outputs have to be like this image (wiki)
http://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/3_phase_AC_waveform.svg/500px-3_phase_AC_waveform.svg.png

Thx

Comments

  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-03-26 22:33
    Well, there are two parts to doing this.

    One is the microcontroller generating 3 outputs of some sort - DAC or PWM or something else... There are decisions to be made about how much resolution you need and how smooth a sine wave you require.

    The other is the MOSfets (or transistors if you insist) that produce the power stage.

    While it can be done with a lowly PIC, the Propeller can use 3 cogs to get this done exceeding well. Much depends on how precise a sine wave you really want. In some cases you just want to power an R/C 3 phase motor, in other you might want to power a 3 phase aeronautic gyro, and other might be some sort of lab device.
  • bill190bill190 Posts: 769
    edited 2013-03-26 23:18
    If you need it to power something, aircraft use 3 phase power and have inverters to create this 3 phase electricity.

    So might want to search google.com for the words...

    aircraft 3 phase inverter

    And also just...

    3 phase inverter

    or...

    3 phase inverter adjustable

    More...
    http://en.wikipedia.org/wiki/Variable-frequency_drive
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-03-27 02:39
    You mentioned a frequency range, a voltage range; but no loading in amps. You will certainly need to have some idea of your loading to get a good result.
  • LeonLeon Posts: 7,620
    edited 2013-03-27 02:50
    http://www.microchip.com/pagehandler/en-us/technology/motorcontrol/motortypes/acim.html
  • TumblerTumbler Posts: 323
    edited 2013-03-27 03:07
    Thx all for the links and tips.
    You mentioned a frequency range, a voltage range; but no loading in amps.
    Need only signals, power is for later...

    Just want to generate a 3 phase sinewave,

    Found some posts and the one i was interested in: sinewave3 and magicSinewaves
    Couldn't test these ones
  • LeonLeon Posts: 7,620
    edited 2013-03-27 03:25
    What is the application?
  • TumblerTumbler Posts: 323
    edited 2013-03-27 03:35
    Leon,

    I only need a 3 phase sinewave signal (P0-P2) for a propeller
    Testing the sinewave files right now....
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-03-27 04:06
    Well, this is a PWM approach and can provide 32 independent sine waves.

    Yes you only need 3, but 32bit resolution is useful.

    http://forums.parallax.com/showthread.php/113685-OBEX-update-PWM_32_v2

    The Propeller 2 will have DAC on every i/o pin and make this even easier to do.
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