IEEE Electrification Magazine - December 2017 - 13

The EDS of the eTaxi contains the following key highpower components:
xx
An ATRU serves to convert the electrical ac power
source to dc voltage. For example, it is used to convert and boost three-phase, 115 Vac at 400 Hz from
the APU generator to ±270 Vdc. A single ATRU can be
used to feed both the WACUs, or each WACU can
have a dedicated ATRU. The second option was used
at the PAS.
xx
The motor controller, also referred to as the WACU, is
used to generate ac voltage to drive the TM. High current is required to deliver high torque (such as breakaway torque) and accelerate the airplane to reach the
desired taxiing speed.
xx
A high-torque, high-power TM needs to be installed
on the wheel actuation system to deliver the required
torque. The motor must accommodate severe environments like shock and vibration. The motor will be
exposed to a heavily contaminated environment as well.
xx
High-power cable harnesses are needed to deliver
electric power from the motor controller to the TM.
These harnesses need to be capable of carrying a high
current and flexible enough to be routed to the motor
mounted on landing gears.
Some key requirements of the ATRU are listed in Table 1,
some key requirements of the WACU are listed in Table 2,
and some key requirements of the TM are listed in Table 3.
Figure 3 shows the entire EDS being integrated and
tested in the lab environment at the Honeywell facility in
Torrance, California.

EDS Protection and Controls
Protection mechanisms are built into the EDS to prevent
component failures from propagating to other components,
including upstream to the power distribution bus. The thermal management and protection of the EDS are necessary
due to the high-power nature of the hardware. Overcurrent

and overvoltage protection for the components is also
required for safety. The components of the EDS will be
installed at various aircraft locations. The harness for connecting these components can be up to 60-70 ft long.
In addition, the number of power cables can be doubled
due to power sharing. The EDS needs to detect and isolate
a failure in the harnesses and the components as well. A
large number of sensors and their associated circuitry
may be required, which could lead to a degradation of

TABLE 2. The WACU key requirements.
dc bus

±250 Vdc minimum

Output power

60 kW at 20 kn of aircraft speed

Communication

Databus, discrete and analog input-
outputs, resolver

Environment

Pressurized area

Power quality

ABD 100.1.8.1

Cooling

Forced air (self cooled)

EMI

DO-160 Rev F

Control

Digital signal processor, built-in-test

TABLE 3. The TM key requirements.
Winding configuration

Three-phase Y connected

Connection

Two parallel cables for equal
power splitting

Shaft position sensor

Resolver

Physical

Fit into the existing allocated
space near the landing gear

Performance

Breakaway torque at zero speed,
rated power at 20-kn aircraft speed

Cooling

Forced air (self cooled)

TABLE 1. The ATRU key requirements.
Power input

115 Vac, 400 Hz, three phase, nominal,
per ABD 100.1.8

Power output

Nominal ±270 Vdc, ±255 Vdc minimum
at full load

Power rating

40 kW continuous, 150% overload for
1 min

Rectification

18-pulse ATRU

Inrush current

4X nominal current

Cooling

Forced air (self cooled)

Environment

Nonpressurized area, DO160G

Efficiency

>95% at full load

Input-output

Temperature monitoring and signals

Power factor

No less than 0.85 lagging at full load

ATRU

WACU

Load Drive

Figure 3. The integrated EDS in the lab environment.

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