IEEE Electrification Magazine - December 2014 - 25

Figure 1. The U.S. battleship USS New Mexico (BB-40) had the world's first turboelectric drive.

engine emulators using vector-controlled ac synchronous
expanded to two sets of engines/generators and three sets of
motors were developed. The emulator replicated the performotors/propulsors to simulate the TeDP system.
mance of the engine, responding to a reasonable subset of
The ironless composite stator of the radial-flux PM motor
generator operating conditions, such as supplying a steady
was modified to provide an extra degree of freedom so the
load, transient loading and unloading, and short- or openstator and rotor can be offset. This axial motion of the stator
circuit faults. In short, it has been shown in the literature
can vary the magnetic field, which allows the PM motor to
that the electrical motor drive system enables the implemore closely mimic a wound-rotor synchronous machine.
mentation of the power-speed characteristics of wind turThe whole system model for all the components in a TeDP
bines and the emulation of the speed-torque characteristics
powertrain in MATLAB/Simulink will be introduced. Also, the
of the gas turbine engines. However, most studies suggested
control algorithm for the emulator will be developed and
the need for more accurate subsystem models, and the
tested through a simulation model.
details of the emulators were not fully described. FurtherGas Turbine System model and
more, an emulation of the propulsive fan maps using
motor-based emulator
closed-loop control of the electric motor drive system has
The goal of this section is to develop a method by which an
not been published.
electric motor drive system can be controlled to emulate the
This article describes how small electrical machines can
steady-state and dynamic characteristics of a gas turbine
emulate all of the components of a TeDP powertrain using
engine as the first powertrain component. The control algothe PEGS. As shown in Figure 3, a line of the subscale powrithm for the emulator will be developed and tested through
ertrain consists of a set of four identical motors and associata simulation model before implementation in the test rig.
ed motor drive/control systems. This set of four motors and
drives mimics the power distributed
from the turbine to the propulsive fan.
The first motor and its drive simulate
the speed-torque characteristic of the
gas turbine engine, while the second
motor and drive act as a generator for
the torque load. The third motor and
drive imitate the wound-rotor synchronous motor that drives the
propulsive fan, which is emulated by
15 Superconducting Motor-Driven
the fourth motor and drive. Finally, the
Fans in a Continuous Nacelle
fourth motor and drive provide the
torque load that the fan would proWingtip-Mounted
duce, which can be derived from the
Superconducting Turbogenerators
flight conditions and implementation
of fan maps. The system has been Figure 2. N3-X hybrid wing-body aircraft with a TeDP system.
IEEE Electrific ation Magazine / d ec em be r 2 0 1 4

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