High Frequency Transformer

I understand the "full bridge", but that does not explain the 30V > 60V part.

A push-pull type is also fully-driven but with less components and has the double voltage part, eg. (just for the topology):
https://i.stack.imgur.com/h826H.png

rjenkinsgb said:

push-pull type

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A push pull has two time more primary turns.
With 60A on the primary it will be very hard to make. Adding more turns increase the problem.
If anything I would increase the switching frequency greatly. 100s of khz. I think every effort should be made to get the primary turns down.
With a resonant supply it may be possible to get near 1mhz. (zero current or zero voltage switching resonant)

running the thing at 10khz will give you RFI harmonics every 10khz, running at 100khz will have harmonics 100khz apart. as an amateur radio operator, i would rather see RFI spaced 100khz apart than 10khz apart (actually i prefer to have no RFI at all, but it's not a perfect world). 100khz is easier to make filters for (smaller capacitors and smaller inductors).

unclejed613 said:

as an amateur radio operator

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I have made some spread spectrum power supplies. The frequency is not constant.
Some of the noise is not from the harmonics of the main frequency but from the speed of the MOSFETs and Diodes along with the L & C in the PCB. My last big supply had a 333mhz noise that was not a harmonic.

unclejed613 said:

running the thing at 10khz will give you RFI harmonics every 10khz, running at 100khz will have harmonics 100khz apart. as an amateur radio operator, i would rather see RFI spaced 100khz apart than 10khz apart (actually i prefer to have no RFI at all, but it's not a perfect world). 100khz is easier to make filters for (smaller capacitors and smaller inductors).

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At higher frequencies parasitics inductances and capacitances of wires, PCB board, transformer, etc start to dominate .

30 volt at 60A to 500V supply; I have never done this.
Think about building 5 small supplies. 30V at 12A to 100V isolated supplies. The inputs are in parallel. The outputs are stacked in series. This I can build.