Total Harmonic Distortion and Efficiency

Discussion in 'The Projects Forum' started by HUMBLE, Nov 2, 2010.

  1. HUMBLE

    Thread Starter New Member

    Oct 24, 2010
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    Finally,I have been given approval to research and build an inverter.

    I have decided that it would be a modified sine wave inverter,it would produced continuous power of 300W and will Convert 12V DC TO 120V AC.

    My question is at what point do I specified the Total Harmonic Distortion and the efficiency?

    Do I randomly pick values for the efficiency and THD and then work to achieve them?
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    The power losses in the switching section and across the output semiconductors will be determined by your component choices, so the parts you use will have an effect on the final efficiency of the inverter. Some of these choices will have to be based on your choosen switching freq. HIgher freq in general are more efficient, but create new problems by operation at the higher freq. that must be addressed chiefly in the layout and physical design.

    I'm glad you think it is a good thing to have gotten permission, because, a few weeks wrestling with this problem, may make you change your mind, and decide that it was a curse and not a blessing. :)
     
  3. HUMBLE

    Thread Starter New Member

    Oct 24, 2010
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    I have broken the circuit that i will use into the following:
    Oscillator
    Pre- Driver
    MOS/Transistors
    Transformer
    I guess my switching frequency is on my oscillator's section?
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Why not just walk into WalMart and buy one? For example they offer a 400W one for $27:
    http://www.walmart.com/catalog/product.do?product_id=11020914&findingMethod=rr

    If your answer is that you need a cleaner wave, then you're halfway to defining your specs.
     
  5. HUMBLE

    Thread Starter New Member

    Oct 24, 2010
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    Buying one would be very easy but this is a project for my degree - good for my gaining experience.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    The most valuable experience is the ability to choose wisely when confronted with a make-or-buy decision. Many companies go under when they make the wrong choices. "Make" is the last resort, but is the right (and only) choice when you need something not available commercially.

    If you can get your degree by reinventing a wheel, go for it. But maybe you'll get extra credit if you add something unique.

    An inverter that would run off lower voltages would be useful to the wind energy crowd. Wind generators can produce plenty of power in low wind, but much gets wasted because there's nothing you can do with, say, 4v. Being able to get 120v AC out of low voltages would thrill this crowd.
     
  7. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  8. HUMBLE

    Thread Starter New Member

    Oct 24, 2010
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    Thanks very much for the link,I am studying it .It holds so much information
     
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