12VDC to 240VAC inverter design

Discussion in 'Homework Help' started by hijo1118, Dec 1, 2008.

  1. hijo1118

    Thread Starter New Member

    Dec 1, 2008
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    0
    Hi,

    i am a bit of a beginner and trying to design an inverter that goes from 12vdc to 240vac at 50hz, with power of 1kw. I need it to have less than 5% total harmonic distortion and be free from harmonics between 150hz and 1.5khz. I am only designing it, not building it.

    I am trying to design a full bridge spwm circuit to do this using sine triangle comparison but am generally a bit confused with it all.

    Do i need a pure sine wave output to ensure the thd is of the required less than 5%? or can this be done with a square wave output? i am struggling to create the reference sine waves and triangle (carrier) wave, what components should i be using, for the sine wave i've read about the need for an up/down counter connected to a voltage controlled oscilator, how does this work and how does it connect?

    I need help as my due date is soon and i'm feeling very confused and like i'm going round in circles! Am i making this more complicated than it needs to be?

    Thanks
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    You need to make a fairly complicated pulse-width-modulation circuit with a high frequency carrier. It switches at a very high current (100A) and drives a high frequency step-up transformer. A filter at the output of the transformer smooths the high frequency pulses into a low frequency sine-wave.

    Commercial inverters use Mosfets to make a high frequency that is stepped up in a transformer. The output of the transformer is rectified and filtered into DC and Mosfets chop it into PWM. The PWM is filtered into a sine-wave.
     
  3. bertus

    Administrator

    Apr 5, 2008
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