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OT: Phase Control Bridge Rectifier

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  • OT: Phase Control Bridge Rectifier

    In all the schematics I've seen for phase control bridge rectifiers they use four SCRs with opposite pairs fired together. Could the same thing be accomplished with only two SCRs and two diodes?

    Even with the two SRCs triggered together it should still work since only one will be forward biased at a time. Or is there some reason to not trigger a reverse biased SRC?

  • #2
    I haven't seen that configuration before, but it seems like it should work fine. I'm not sure whether you can keep an scr in reverse blocking with a trigger voltage applied- if you look at a breakdown of the structure of an scr, it would seem that it will work this way. There is likely a reduction in the voltage that it will block with the turn-on voltage applied, but you would spec the part to be able to function in the circuit anyway depending on the voltage you're working with.

    Don't take this as gospel- I haven't worked with scrs for some years now and I'm not fresh on it.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


    • #3
      The two SCR's in a bridge is common and used in many of the KB/Baldor DC drives, 2 quadrant control.
      In the 4 quadrant, 4 SCR provides dynamic braking.