I'm not sure how much I can say, since there is quite a bit of proprietary data involved [Linked Image]

The Chorus technology is my personal baby; I spend my day trying out different winding designs and control approaches, and trying not to blow up transistor arrays. (I've gotten pretty good at this, our last failure was not a transistor, but a 900V capacitor bank letting go at 1200V, ooops)

The whole reason for Chrous in this application is _overload_ operation. These motors are not used at their continuous rating, but instead at their 5-15 minute rating, and are expected to go from ambient (40C) to maximum winding temperature (180C) over the course of operation. Chorus motors work very well in this sort of operating regime.

I will say that the power levels involved in an airplane are causing things to move to 480V electrical distribution, and because the alternators are a 'parasitic' load on the jet engines, there is a strong push to 'wild frequency' power.

Air conditioning is currently done with 'bleed air'. Air is compressed at the front of the jet engine, mixed with fuel, burnt in the center and shot out the back. Air for the AC is 'bled' off prior to being mixed with fuel. This, of course, means that the air is not available for thrust production, so one goal is to get rid of bleed air, instead using electric power for air conditioning and cabin pressurization. This is a very large electrical load.

Compared to all of the other loads, actually moving the plane at low speed is pretty small.

BTW, bringing this back on the electrical topic, this was the project that got me looking at impedance grounded systems. For the demo system, we were not covered by NEC, but we wanted to maximize safety and minimize any chance of damage to the aircraft in the event of a ground fault. In particular, in the event of a ground fault, we didn't want however many hundreds or thousands of amps flowing through the aircraft chassis until a breaker tripped. So we powered the system from a 277/480V wye source with a 50 ohm resistor between neutral and ground. We used a ground fault relay set at 2A tied to a shunt trip on the main breaker. A bolted ground fault would cause about 6A to flow, and as soon as a fault was detected we would trip out the source. The major point that was not NEC compliant was that there were a few line to neutral loads.

-Jon