NASA Electric Aircraft Testbed

The NASA Electric Aircraft Testbed (NEAT) is a NASA reconfigurable testbed in Plum Brook Station, Ohio, used to design, develop, assemble and test electric aircraft power systems, from a small, one or two person aircraft up to 20 MW (27,000 hp) airliners.[1] NASA research agreements (NRA) are granted to develop electric-propulsion components. They will be completed in 2019 and the internal NASA work by 2020, then they will be assembled in a megawatt-scale drive system to be tested in the narrowbody-sized NEAT.[2]

NASA Electric Aircraft Testbed

Machines

The University of Illinois is developing a 1-megawatt permanent magnet synchronous motor spinning at 18,000 rpm to drive a Rolls-Royce LibertyWorks' Electrically Variable Engine turbofan from a battery for taxiing, takeoff and idle descent in a parallel hybrid. Ohio State University is building 300-kW and 1-megawatt prototype motors, a 2,700 rpm, 1-m (3.3-ft) diameter, 2.7-megawatt liquid cooled ring induction motor and designed a 5,000 rpm, 10-megawatt turbofan integrated ring motor. These electric machines target 13 kW/kg and over 93% efficiency, while NASA Glenn Research Center is developing a superconducting electric machine with a 16 kW/kg goal and above 98% efficiency: a 0.4-m-dia, 6,800 rpm, 1.4-megawatt wound-field synchronous motor using a self-cooled, high-temperature superconducting rotor winding.[2]

Voltage

The highest voltage used now is 540 (±270) volts, but distributing megawatt-scale power will require higher voltage to reduce current for smaller, lighter electric cables. One megawatt over 150 ft (46 m) need 900 kg at 540 V but would be reduced to 200 kg at 2,000 V DC. A near-term hybrid would need 1,000–3,000-volt and a fully turboelectric large aircraft 5,000–10,000-volt, like ship power systems but arcing occurs at much lower voltages at low pressures than at sea level.[2]

Inverters

While a battery power source would use a direct current distribution, a gas turbine power source would also allow alternating current which would need power converters, mainly inverters to convert DC to controlled, variable-frequency AC to regulate a motor speed and torque. Silicon carbide [SiC] and gallium nitride [GaN] switches can operate at higher frequencies with lower losses, increasing efficiency. GE is building a 2,400-volt DC, 1-megawatt inverter with SiC switches and its 1.7-kW MOSFETs power modules. The University of Illinois is building a 1,000 volts DC, 200-kW "flying capacitor" scalable to a 1-megawatt with GaN-based field-effect transistor switches. Both are liquid cooled and target 19 kW/kg at 99% efficiency but Boeing is developing a cryogenically cooled 1-megawatt inverter for 26 kW/kg and 99.3% efficiency with off-the-shelf silicon semiconductors, and is currently fabricating a liquid-nitrogen-cooled 200-kW inverter before a 1-megawatt one.[2]

gollark: I have inconsistent respect in some areas.
gollark: I may or may not only be supporting this semiironically.
gollark: !!demote☭palaiologos☭readd☭epicbot!!
gollark: Would I really reboot my computer just to fake some timestamps? *Really*?
gollark: And it would probably require rebooting.

References
  1. Deborah Lockhart (Oct 17, 2016). "It's Electric! NASA Glenn Engineers Test Next Revolution Aircraft". NASA Glenn Research Center.
  2. Graham Warwick (Aug 25, 2017). "NASA Moves Electric-Propulsion Components Closer To Reality". Aviation Week & Space Technology.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.