By indicating that all SCR's could be on I was referring to per bridge, as of course to get reverse polarity full wave, requires two bridges.
All you need to get a bridge output is permanently turn all on of one bridge,
the SCR drive was replaced with the appearance of IGB transistors IGBT's ( Mosfets came later).
SCR's though, cannot be PWM controlled, once turned on they stay on until power is removed or reverse commutated, (complicated).
They are fired by turning them on early or late in the duty cycle and they remain on for the duration of that half cycle until it reaches zero.
You only need 6 diodes for a FW 3ph bridge and the ripple freq. is 6x input frequency so the ripple is far less than 1ph.
Al.
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CNC, Mechatronics Integration and Machine Design.
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Last edited by Al_The_Man; 05-30-2006 at 03:22 PM.
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