Buck/Boost or ???

My situation is simple. But the answer to remedy the situation ...... Well, I'll need some expert advise on this one.

I've got a Sharp 2412 VMC connected to a Phase Perfect DPC-20 digital phase converter. I also have 3 other small pieces of equipment, all connected to the concverter via a 100 amp 3 phase panel.

My problem is that my incoming 240V single phase is more like 245 volts. which normally would be a good thing. But in this case is causing me problems, due to the fact that the Sharp VMC is calling for 220 volts, and the factory says 245 is just too hot, and will eventually cause problems. Of courst the converter puts out what it takes in, voltage wise.

My questions:
First is it better to step it down prior to the phase converter with a single transformer or afterwards before the VMC. Forgetting the other machines for the moment, and forgetting for the moment, the cost issues. And then, am I correct in assuming that stepping down the 3 phase would be more expensive due to needing at least 2 and maybe 3 transformers ? But perhaps they would be smaller and thus cheaper ?

Also, is using Buck/Boost transformers the right approach or should I be looking for a regular transformer on the 3 phase side of this probem ?

And last but not least, and the most difficult for me.... Help in sizing.....

I've got 100 amp wire and breaker on the single phase side to the converter (rated at 88 FLA) and a 50 amp circuit out to the machine (rated 15KVA which I believe is 36 amps) soooooo WHat size transformers would be required in each scenario?

I also run into transformer type issues... ie.
Type M ??
Type L ??
Type LM ?

Thanks in advance
Nolan

The required autotransformer ratio is 220/245 = 0.898.

Let's call that 0.9.

Were you to install two buck/boost autotransformers, in buck mode, one being from L1/A to B, the other being from L2/C to B, and each having a ratio of 0.9, you would be transforming the A-C voltage from 245 to 220, which certainly meets your VMC's requirement, but the N-B voltage would remain 0.867 * 245 = 212, which is what the Phase Perfect will put out for its 245 input.

This would result in A-B and C-B voltages which would be about 239, and would result in 220-239-239, which is still too high for your VMC, on two of its three phases.

It is probably best to install a three-phase transformer on the output of the Phase Perfect, just for your VMC.

The Phase Perfect would put out 245-245-245, and the three-phase transformer would transform that to 220-220-220, which meets the requirements of your VMC, on all three phases.