[UFO]

"At a later stage I plan to ramify this to a power factor buck converter for 144V battery packs."
Can you explain this a bit more? Is this just another way of stating a simple PFC to high voltage DC, or are you bucking down the PFC voltage? If you are generating a high voltage simply to buck it back down, why? It seems to me a PFC can regulate a DC voltage well enough to directly run the motor controllers.

It looks like you are aiming very high, and I respect that, but targeting your 6kW charger to operate from both 230 AC and 48-350 DC sounds difficult without a significant efficiency loss at lower DC. I guess that is why you are limiting power at lower voltage inputs.

"So far I am using an interleaved aproach consisting of two UC3842 current controllers. These receive the clock pulse from a microcontroller and a modified feedback signal to draw line current in phase with the line voltage."
Are you synchronizing your UC3842s 180* out of phase? Is this simply to lessen the current ripple on your PFC? I'm not sure why this would require synchronization with line frequency since the PFC should be regulating this directly.

"I'm looking at suitable inductors that could be used for a 50 or 60KW version."
That is a huge step up. You are going to use the control scheme and scale up the magnetics. Presumably you are scaling up the switches too, and the drivers and the current sense circuits too, but what about your input source - do you still have use of 48VDC input? That is a massive scaling of current from 100A to 1000A at least.

What use do you see for this kind of power? Is this a very quick charger? What battery banks can take this kind of potential charge rate?

Lots of questions, love the ideas.