IEEE Electrification Magazine - December 2014 - 34

The electric
power from the
turbogenerators
is distributed
along redundant
superconducting
electrical cables
to an array of
superconducting
motor-driven fans.

courtesy of nasa

shown in Figure 11. This inexpensive simulator will mimic
two turbine engines and three fans, interconnected by
generators, rectifiers, a dc bus, inverters, and fan drive
motors. A TeDP system using all ten motors and drives
with closed-loop controllers makes it possible to simulate
a representative part of the TeDP powertrain. Currently, a
Rolls-Royce fail-safe code of TeDP for future hybrid wingbody electric airplane is under investigation for implementation using the PEGS.

Planned Future Study
In this article, we presented 1) the development of an analytical model of all the components in a TeDP powertrain
using MATLAB/Simulink and 2) the subscale experimental system to emulate the power distributed from the
turbine to the propulsive fan. The operation principle
behind the technology is that all rotating components
can be represented by torque and speed curve sets. Simulation results have shown that their dynamic characteristics can be implemented by using the closed-loop
control of the electric motor drives. In the near future,
additional turbogenerators and electrically driven fans
will be added to further replicate the full propulsion
powertrain. Planned future study includes 1) characterizing the experimental interaction of the many electrical
components, 2) testing and evaluating parametric performance, 3) validating system model analyses and predictions, and 4) analyzing transient response (including
faults), grid stability, and internal autonomy experiments.

For Further reading
H. D. Kim, G. V. Brown, and J. L. Felder, "Distributed turboelectric propulsion for hybrid wing body aircraft," in Proc. Int. Powered Lift Conf., London, England, July 22-24, 2008, NTRS Paper
ID 20080021214.

I E E E E l e c t r i f i c ati o n M agaz ine / december 2014

J. L. Felder, G. V. Brown, H. D. Kim, and J. Chu, "Turboelectric
distributed propulsion in a hybrid wing body aircraft," ISABE2011-1340, 2011.
G. V. Brown, "Efficient flight-weight electric systems," in
Proc. 2012 Technical Conf., NASA Fundamental Aeronautics Program, Subsonic Fixed Wing Project, Cleveland, Ohio, Mar.
13-15, 2012.
B. A. Correa, A. Smith, W. Jiang, and R. A. Dougal, "Gas turbine emulator for testing of high-speed generators," in Proc.
IEEE SoutheastCon, 2010, pp. 226-229.
K. Voigt, "A control scheme for a dynamical combustion
engine test stand," in Proc. Int. Conf. Control, 1991, vol. 2, pp. 938-943.
S. K. Yee, J. Milanovic, and F. Hughes, "Overview and comparative analysis of gas turbine models for system stability studies," IEEE Trans. Power Syst., vol. 23, no. 1, pp. 108-118, Feb. 2008.
L. N. Hannett and A. H. Khan, "Combustion turbine dynamic
model validation from tests," IEEE Trans. Power Syst., vol. 8, no. 1,
pp. 152-158, Feb. 1993.
W. I. Rowen, "Simplified mathematical expressions of
heavy duty gas turbines," Trans. ASME J. Eng. Power, vol. 105,
no. 4, pp. 865-870, Oct. 1, 1983.
M. Armstrong, C. Ross, D. Phillips, and M. Blackwelder,
"Stability, transient response, control, and safety of a highpower electric grid for turboelectric propulsion of aircraft,"
NASA/CR-2013-217865, E-18658, June 1, 2013.
B. Choi, C. Morrison, T. Dever, and G. Brown, "Propulsion
electric grid simulator (PEGS) for future turboelectric distributed propulsion aircraft," in Proc. 50th AIAA Joint Propulsion
Conf., Cleveland, Ohio, July 28-30, 2014, Paper 1952083.

biography
Benjamin B. Choi (benjamin.b.choi@nasa.gov) is an aerospace research engineer at the NASA Glenn Research Center conducting research on the development of bearingless high-power-density motors for future NASA missions.
He recently expanded his research to the development of
technology for a future hybrid wing-body electric airplane
with a turboelectric distributed-propulsion system.

Table of Contents for the Digital Edition of IEEE Electrification Magazine - December 2014