Re: [CAD_CAM_EDM_DRO] Sizing Rectifiers

In a message dated 30-Nov-01 23:33:38 Central Standard Time,
ccq@... writes:

> I've Never heard of a full wave _6_ diode bridge. I've seen plenty of 4
> diode
> bridges circuits, but never a 6. What do you do with the extras?
>
>

Bill: Read again, THREE phases! That's three separate
transformer-secondaries (six wires), connected in a "delta" configuration
(three "terminals"). You connect TWO diodes to each "terminal", each facing
opposite directions, and the other ends of those, then, to the pos. and neg.
outputs. Repeat for all-three terminals. Two times three is SIX. Did I do
the math right? (I flunked Differential Equations!). This is "Full-Wave,
Three Phase". It gives you a ripple-frequency six times higher than
half-wave, single-phase, so, each "bump" is very short and of low
potential-difference. Thus, the "filtering" is very easy, and the "raw DC
out" is nearly equal to PEAK-AC voltage (1.414 x RMS, isn't it?).

A three-phase rectifier, all else being equal, is more expensive than a
"good, full-wave single-phase", but it gives a nicer, easier-to-regulate
DC-out, it does! (Not worth that extra in many cases, but good when
high-currents are needed, with decent regulation).

Hope to have been usefully helpful! Jan Rowland, Troll


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