Yes. Variable speed motors use variable frequency and voltage AC. The voltage limit for AC motors is probably in the 10 KV range although I think 1KV to 2KV is more common.KitemanSA wrote:MSimon and I were discussing compactness, primarily with respect to use aboard Naval vessels. I cannot currently imagine a Naval vessel that would require anywhere in the neighborhood of 6GW. Indeed, most Naval uses would be in the 100MW size that Dr B proposed to begin with (Navy funding, no coincidence).93143 wrote:I think he was thinking of a coil gun.
Just out of curiosity, how much would a 6 GW DC-DC converter capable of stepping down from 1.5 MV to maybe 1-10 kV actually weigh? How big would it be? Would it weigh more than a 6 GW BFR? A lot more? I suspect so, but I want to make sure...
Power electronics is not my gig, but don't variable speed electric motors like those that would be used for Naval propulsion all essentially convert supply power to DC and then reconvert back to proper frequency AC? If so, mayhaps a DC supply from the BFR would skip two evolutions and be a better fit to start with. Anyone?
So you have to downconvert the 2 MVDC to about 15KV to get 10KV AC. (peak vs RMS)
And yes 100 MW is an excellent size for ships - the first submarine production reactors were in the 30 MWth range. Also the 100 MW size is about the limit for conventional cooling. So it all fits together nicely.
Figure 10 MW for actual net electrical/mechanical power - that is 10 KV (RMS) @ 1,000 amps. Roughly 10,000 HP.