Power thyristor firing for phase control??

Discussion in 'Power Electronics' started by Abdel_Rahman, Oct 14, 2016.

  1. Abdel_Rahman

    Thread Starter Member

    Jul 19, 2016
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    Can I use this circuit for triggering - back to back - power thyristors used for phase control??
    Is there any errors in this diagram??
    note: thyristors gate current is about 250 mA and used for switching 380 V
    triggering.png ??
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,967
    744
    Thyristors back to back are usually fired with pulse transformers across C and G, not opto couplers.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If switching the same phase, which you appear to be, then why not a Full wave bridge? Two rectifiers, two SCR's..
    Max.
     
  4. Abdel_Rahman

    Thread Starter Member

    Jul 19, 2016
    36
    0
    Is there any circuit for firing power SCRs with pulse transformers

     
  5. Abdel_Rahman

    Thread Starter Member

    Jul 19, 2016
    36
    0
    I did not understand.
    note: rectifier will be full wave bridge and 7812
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It can be done with a full wave bridge with either SCR's in the bridge or a bridge followed by a Triac.
    Google SCR full wave bridge.
    This shows a 4 quadrant bridge, if you only need a two quadrant, use regular diodes for SCR1 & SCR3.
    Also search this forum for a MC-60 controller to see an application of a SCR bridge.
    Max.
    upload_2016-10-14_11-9-34.png
     
  7. Abdel_Rahman

    Thread Starter Member

    Jul 19, 2016
    36
    0
    That's my error as my drawing is not so obvious:(, here is an update for it
    >>
    triggering.png
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Here is a circuit using scr's with pulse transformers, for a universal motor.

    DSC_0245.JPG
     
  9. Abdel_Rahman

    Thread Starter Member

    Jul 19, 2016
    36
    0
    the power section of my attached image is a spot welder exist, but its control/firing circuit has been defected, so I ask if that control circuit will work if implemented
     
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