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Single phase half bridge converter working help

  1. Sep 15, 2012 #1
    why are we using two diodes instead of two scrs in a single phase half bridge converter? What difference does it make? (say in my attachment s2 and s3 are diodes instead of scrs?)
    Wont we get the same operation with two scrs itself (only thing you have to fire them together with s1 and s4). Im confused. Please help.
     
  2. jcsd
  3. Sep 15, 2012 #2

    NascentOxygen

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    Staff: Mentor

    electricallov, your attachment is missing.
     
  4. Sep 15, 2012 #3
    Im sorry. Now ive resubmitted.
     

    Attached Files:

  5. Sep 15, 2012 #4

    NascentOxygen

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    Hi electricallov. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    Offhand, I can't see a reason for not using 2 SCRs and 2 diodes here, at least for resistive loads. (Highly reactive loads can pose problems for SCRs, so I'd need to examine this closely to see whether that may be a consideration, especially when the L element is shown so prominently in the schematic here. :wink:)
     
    Last edited by a moderator: May 6, 2017
  6. Sep 15, 2012 #5
    In my humble opinion,
    if you use all four SCRs then you would end up with negative voltage output for a short duration before s2 and s4 are triggered.
     
  7. Sep 15, 2012 #6
    GingerLee, this negative voltage concept solves everything. I did not notice the freewheeling path created when the two scrs are replaced by two diodes. This solves my question. Thanks
     
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