Ignoramus8092 wrote:

Thank you Guy. My plan is as follows: wire the transformer as three
phase Wye, and use three SCR half bridges in a scheme similar to that
by PCTI. These three half bridges will be added without disturbing
current SCRs.

I have six secondaries, two on each leg, I will parallel each pair.

Does it make sense?

That appears to be correct, subject to the usual limitations of talking
about a circuit rather than having it in front of me. Normally I bring
up any such circuit slowly with a three phase variac or, in a pinch,
with three single-phase variacs and a lot of moving from knob to knob.
You might also consider using temporary fuses to do the paralleling at
first as an extra precaution. All of the jumpers we use in our lab have
inline fuseholders; putting a regular clip lead across a 440V 2KA supply
by mistake makes quite a spectacular flash.

--
Guy Macon
http://www.guymacon.com/