pure sinewave inverter.

Discussion in 'The Projects Forum' started by jblueink, May 30, 2008.

  1. jblueink

    Thread Starter Member

    May 27, 2008
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    how can i build a sinwave inverter say 1KVA using PWM or any other componenet.and also things to consider when designing it.
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    I recommend you buying one, it will be more well designed and more efficient.
     
  3. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    I don't know how your question did end up here. This should belong to the projects forum, not to the projects collection.

    Strange!

    But if he really wants to design his own? I hope I'm not being rude. I'm just asking.
     
  4. jblueink

    Thread Starter Member

    May 27, 2008
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    am sorry for posting a question at the wrong place.
     
  5. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    It is not your fault. It is strange since the particular forum has moderation right after posting.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    In essence, your sine inverter is going to be a big audio amp with a sine oscillator driving it. Did you have some power source in mind to run it on?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Building an efficient and reliable inverter capable of 1KVA is a daunting task.

    Your question is one of those one-liners that would require hundreds of pages of text to answer thoroughly.

    Frankly, I don't feel like typing that much text. But here's an intro:

    Basically, modern inverters create a pseudo-sinewave output by approximation; there is a monitoring circuit that sets a goal for the particular slice in time, then turns on the appropriate output transistors/MOSFETS/IGBT's until the instantaneous target voltage is reached; then they're turned off. Then the next goal is set, and the process is repeated, at a frequency from perhaps 600hz to 70kHz. The output waveform is actually a series of small steps. Sometimes, it's run through a large inductor or a filter that removes the high-frequency transients; but that's in the more expensive units.

    Cheap units just make a really rough approximation. The output isn't suitable for many applications.
     
  8. jblueink

    Thread Starter Member

    May 27, 2008
    24
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    well BEENTHERE thanks for your question.i intend to use a car battery say 12V 80AH.

    sgtwookie,i found this chip SG3524N and in the circuit where it is used i think i serves as a PWM then followed by four IRF150 as the driver.
     
  9. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    12V 80Ah has capacity of 960Wh, that means you will have power for cca 50 minutes at full load. That´s not that much.

    And can the battery produce 1kW continuously?
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    So, 1KVA @120VAC means 8.333...A output. If a hypothetical inverter is 100% efficient, and your battery holds at 12v for it's 80AH rating, you'll have less than an hour's worth of power. More realistically, you'd probably get more like 15-20 minutes worth of power out of it.

    Automotive batteries aren't designed for applications like this; they're designed for perhaps 10 to 30 seconds of the heavy load of starting the engine, and then need to be recharged completely. They won't last long at all in this kind of an application. You'd need deep-cycle batteries.

    If the application was to be used outdoors, you could use deep-cycle marine batteries. If used indoors, you would have to use SLA (sealed lead-acid) type batteries, which won't emit hydrogen and oxygen gasses like the other types will. It would be far too dangerous to use the non-sealed type lead-acid batteries indoors.
     
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