Triggering Multiple Scrs in series and parallel

Discussion in 'The Projects Forum' started by samirraval, Feb 21, 2013.

  1. samirraval

    Thread Starter New Member

    Feb 21, 2013
    I am making cycloconverter circuit. It is step down cycloconverter.Circuit is midpoint cycloconverter.(please see attachment)
    Now there are four SCRs used.

    It is required that SCR P1 is triggered for first positive waveform,
    P2 for first negative, P1 for second positive.

    Again N1 for second negative, N2 for third positive and N1 again for third negative.

    I had previously done R triggering of single SCR. But when multiple scrs are to be triggered in some pattern, is microprocessor based triggering only alternative?

    Even if I use UJT based triggering, then who will tell the UJT to give pulses for certain duration to P1 and then for certain duration to on... ?
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  2. DickCappels


    Aug 21, 2008
    Think about using small trigger transformers to fire the SCRs.

    Source: in a post by Winfield Hill.

    Using a picket fence pulse train is a very good way to assure that the the SCRs turn on as desired. Be sure you fully understand the SCR's ratings so you can assure that the drive pulse energy and duration is adequate.

    You can use many methods of generating the firing patters. Microcontrollers might be an excellent way provided the "juggling" of the pulse trains does not get too complicated. Other approaches based on discreet logic or programmable devices can work too -choosing the method of generating the firing patterns should be at least half the fun of designing something like this.

    Sorry for the general nature of the reply, but this is all I can do given the level of detail in your post.