scr/thyristor inverters

Discussion in 'General Electronics Chat' started by ajrenzetti, Feb 15, 2011.

  1. ajrenzetti

    Thread Starter Member

    Dec 20, 2010
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    Ive heard that there are certain high power inverters, mainly for induction heating, that use scr's or other thyristors instead of mosfets or igbts. I know that scr's will remain on if the current going through it is higher than a certain point, even if the gate signal stops. I know there are such thyristors called GTO's and SCS's that can be controlled better by a gate signal, but what i want to know is how someone can make an inverter using an scr. i know that there are ways to forcefully turn them off, but i couldnt find any schematics of them.

    If anyone knows how, or even has a schematic or simple circuit diagram of an scr inverter, that would help a lot. The type of inverter im looking for is a half-bridge type or full bridge type, but others giving a high frequency output would be nice too.
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    no such luck...why don't u use google.
     
  3. ajrenzetti

    Thread Starter Member

    Dec 20, 2010
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    i have tried using google, and nothing valid seems to come up.

    by the way, what do you mean by no such luck?
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    We do not have such schematics buddy...
    Even if we did, it would take a lotta trial and error runs to get it working perfectly from your part.
     
  5. BillB3857

    Senior Member

    Feb 28, 2009
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  6. t_n_k

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    Mar 6, 2009
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  7. ajrenzetti

    Thread Starter Member

    Dec 20, 2010
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    i recently found what i think might work as an scr inverter. one of the schematics is in a pdf file, the others i got after a lot of searching on google.

    http://www.freepatentsonline.com/3702432.pdf

    http://www3.telus.net/chemelec/Projects/Misc-Circuits/SCR-Flipflop.png (for this circuit, i was thinking of replacing the light bulbs with a primary winding to a transformer that has to primaries and one secondary.)

    http://farm3.static.flickr.com/2020/1806840205_3e6b32c570.jpg (this circuit is more of an oscillator, but i was wondering if it could be altered into an inverter.)

    I dont have a SPICE simulation program so i cant really tell if these would work or not. any help with that sort of stuff would be really great.
     
  8. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    If this isn't just a thought experiment, then one way to decide how to proceed is to specify what you intend to achieve or physically construct - if that's your goal.

    What will be your load?

    What power level are you considering?

    What frequency of operation is expected?

    Where does the input energy come from?

    And so on ....

    You could also share your spice model circuit with us. We may then be able to better comment.

    Forced commutation isn't mandatory, even for SCR circuits - AC line commutated inverters being a case in point.

    Why the insistence on SCR technology?
     
  9. awright

    Well-Known Member

    Jul 5, 2006
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    Google, "SCR Induction Heater," and look for Dan's Workshop. He describes his experimentation creating an induction furnace for melting iron.

    Westinghouse made a high powered SCR inverter for (I think) induction heating back when SCRs were almost the only really high power semiconductor and published an App. Note on the design. In fact, I think I have the actual inverter hardware buried somewhere in my junk collection and the App Note in my composting literature collection.

    I'm not sure an SCR based design would have any advantages over one based on MOSFETS or IGBTs, neither of which were available when Westinghouse created the design.

    awright
     
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