A little clarification on what you might consider as 'high speed' and 'high power' would be useful, as without quantification this would mean different things to different people.

EDMS Australia

30 KVA or more at 400 Hz.? Try aircraft parts.
Faster than that will probably be special built for the turbine manufacturer.
At 60 Hz, the maximum speed of a conventional alternator is 3600 RPM.
Higher speeds are possible if the output is rectified and then inverted back to a more usable frequency.
Maybe you should be looking at high speed reduction gear sets.

Bill
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"Why not the best?"
Jimmy Carter

Hello- I am looking for 8000 rpm and 400 kw, I suppose high frequency, about 600 V.
Anything between 150 and 400 kw could be suitable- It is for a high-speed genset for a hybrid aircraft-basically a giant quadcopter
Running at full power would result in a 200 mph breeze - a little dangerous to be near! :) - the prop(s) airflow would likely have a bit of a hernia, too.
I would like to try running it off a heavily turbocharged 4 cylinder motor- with beefed up internals..
It looks a bit like: any users get theirs custom built, and buy many of them. Not really off-the-shelf.

Lets go back to basics and see what we can do.
You want 400 KW at 8000 RPM.
A typical generator turns at 1800 RPM.
HP or mechanical KW is proportional to Torque times RPM.
If you go from 1800 to 8000 RPM you theoretically can increase the power from 90 KW to 400 KW.
An induction motor rated for 1760 RPM will turn at about 7820 RPM.
Your challenge is to find 60 Hz equipment that will take the mechanical forces associated with those speeds.

Bill
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"Why not the best?"
Jimmy Carter

Indeed I think this is custom build territory. Now to find someone who will build one-offs, at normal hourly rates.
A lot of the components should be common from standard motors/alternators. It likely needs to be water-cooled.
In New Zealand, it is hard to find someone who actually advertises these service. Maybe a motor rewind outfit,if they get into water-cooled custom stuff? I will find and ask a few.

This is in the same performance regime as the motors in modern electric cars. Those motors are certainly specially designed for those applications. Find out who is making those. Or perhaps you could buy one that is of a permanent-magnet design and re-purpose it.

A planetary gear set may be worth its weight.
I like the electric car suggestion, Brian.

Bill
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"Why not the best?"
Jimmy Carter

I have some queries out to rewinders, thanks.
The main problem is 4 x the heat, and 1000-odd amps is a bit high.
We need to go to 1000 v plus, with associated air gaps etc, plus extra cooling.
We need a motor designer to lay it out, and see what can be done with any standard parts.
I then need to follow this downstream to motors, transformers, inverters, control etc.

1000 V is not so good for general use- I prefer 500-600 V -not so much risk of explosions, death, instant sunburn, etc.

A hybrid drive off a very powerful V8 might be big enough- I don't know of any common ones. Porsche sports car??

So, clearly, you're not in the off-the-shelf market. Micro-turbine units are allowed to "run wild" and the output is rectified to DC and reconverted to AC at a useful frequency. They may even be PM DC machines rather than AC machines, saves the rectification step. You need an electrical machines person at the heart of your team or you'll never move beyond the conceptual stage (necessary, but perhaps not sufficient).

Apparently the tesla model 3 motor is 211 kw peak, 45 kw continuous. I am not sure if it is water cooled? I will check.
It is permanent-magnet synchronous, and probably worth a look-see for sizing and general tech.
211 kw continuous I could work with, just to get going. This could be reworked as an alternator by a moderately competent
electronics guy. More of them around than full-blown electrical engineers.
I will look for more of these type motors. It has an output reduction, which could possibly be removed to drive it fast.
Most likely it would need a new fabricated end cap/bearing mount..

I have found a supplier for specialist electric motors for aircraft. (MGM-Compro). Possibly one of theirs can be used as a generator.
Waiting on a reply.
Now to find aviation-rated reduction boxes with a prop-mount output shaft.
I have put this on the rotorcraft forum.

Hmmm...wonder if you could Frankenstein one of these motors to the gas turbine part of an off-the-shelf turbocharger with variable nozzle technology...

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]