IEEE Electrification Magazine - December 2017 - 15

long cable, the filter configuration in the components
for power quality, the dynamics of the electric actuator,
the parameter sensitivity of the motor and power electronics, and even the voltage dynamics of the generator
and the generator control unit can contribute to EDS
internal voltage bus instability. There are several techniques, such as generalized state space averaging and
dq frame modeling, that can help in analyzing the stability of the EDS and ensure stability over the entire
operational envelope. This research is ongoing and will
be a focus of future work.

EDS Performance Verification
The EDS performance was verified using a dynamometer
drive setup. The TM was coupled through a torque/speed
sensor to a gearbox that was, in turn, connected to a load
generator. The torque of the loading generator is controlled to perform a simulated load to the motor. The generated power is fed back to the local utility grid. The
laboratory setup is used to verify the required performance speed/torque performance shown in Figure 1. The
test results are plotted in Figure 6.
The desired motor torque in the EDS is commanded
by the system controller. When driving a permanent
magnet synchronous machine (PMSM)-based motor
using unity power factor control over the entire speed
range, the motor torque is linearly proportional to the
motor current. The current command to generate the
required torque is a minor task and is fairly accurate.
However, when flux weakening is utilized, the relationship is more complex. Correction equations were generated and used, and final adjustments were needed using
empirical data to meet the accuracy requirements.

Major Requirements of an
ac-to-dc Power Converter for eTaxi
Power quality is a major concern for an aircraft employing
eTaxi because of the large power demand required by the
EDS. The power quality of the EDS and the equipment on
the same power buses need to have much more stringent
requirements to ensure that all the power supplies and utilization equipment function together properly.
For power supply (generation) equipment, additional
monitoring features need to be implemented to detect
and isolate equipment, or groups of equipment, that may
experience a power quality issue. This isolation capability
is important for protecting the other operating power supplies and utilization equipment.
For power utilization equipment, strict power quality
requirements are imposed. Some reasons for the requirements include the following:
xx
The equipment contributing to the power quality
problems could cause other equipment to fail.
xx
The equipment could be prevented from achieving its
design performance, and reliability could be affected
due to the reduced power quality of the source.
xx
Perhaps to meet a desired minimum weight, the
equipment designed with no power margin could
tend to be more susceptible to power quality issues.
Also, the equipment designed to minimize weight
could tend to create power quality issues.
xx
The equipment could fail due to self-generated power
quality problems.
The power quality requirements for ac electrical
equipment consist of a large number of parameters, such

Torque (190-Nm Command, Clockwise Direction)

200

Torque (Nm)

AC-to-dc Conversion

100

Peak Torque
for Breakaway
0

Steady
Torque for
Acceleration

2,000

Maximum Power-Limiting Region

4,000

6,000

8,000

10,000

Motor Speed (r/min)
Figure 6. The measured torque versus speed test data.

IEEE Elec trific ation Magazine / D EC EM BE R 2 0 1 7

Table of Contents for the Digital Edition of IEEE Electrification Magazine - December 2017