Aerospace & Defense Technology - October 2022 - 22

Military Electronics
New Voltage Standards Taking Cues From Automotive Advances
Power system design for systems at altitude is entirely
different from the design of power systems integrated
into automotive and racing vehicles. That said, is
it surprising that a motorsports technology provider is
part of the project team for Tempest, the UK's 6th generation
combat aircraft?
Tempest replaces the Royal Air Force's Typhoon
and is expected to come into service in the mid2030s.
The fighter is an ambitious undertaking that
will predictably need extended amounts of electric
power as well as upgraded, higher power for distribution
to various advanced systems across the aircraft.
Tempest anticipates including augmented and virtual
reality interactive cockpit displays, drone management
capabilities, and advanced stealth and data fusion
technologies.
Here the automotive industry has insight to share,
long focused on energy storage and designing secondary
loads powered by DC sources. Implementing battery-driven
systems may be a more familiar challenge
for automotive power system designers, however, the
demand is still shifting toward higher voltage systems
used for heavy end-loads and distribution across a vehicle.
Incorporating 800 VDC systems as a standard,
Porsche Taycan provides a luxury example - cable size
and weight are minimized, supporting high-end vehicle
performance and speedy charging.
In contrast, 270 volts has emerged as the DC power
distribution system standard in the current civil aviation
market. But future platforms are intent on extending
this to 540 volts since +/-270 volts can be effectively
attained on an aircraft even at typical altitudes - an
environmental factor that has unique impact on power
system design. For example, breakdown or arcing perform
differently at altitude, adding a new design challenge
in the already complicated world of high-voltage
power distribution.
However, electric aircraft, including urban air taxis, do
not normally operate at the altitudes required by civil or
military aircraft. Without this limitation and given their
need for more robust electrical requirements, these
craft can easily operate at higher voltages and may
mimic the automotive market's currently established
800 volt standard. The altitude parameters for military
applications, however, may drive to a different optimal
distribution voltage.
ondary distribution of 28 volts. Because
the secondary 28-volt network can be
designed to support power needs of several
devices via a single conversion, system
developers can avoid designing
voltage step down into each specific
load. This adds critical value for power
electronics servicing relatively isolated
or difficult to access areas of the aircraft.
It's a strategy that also reduces cable distances
and, therefore, weight as higher
voltage power is distributed and converted
locally at the device. Designers
will, however, find complexity increases
when secondary loads must deliver a
range of voltages, powering systems,
and subsystems requiring three, five, or
28 volts.
Modular Power Designs
Experience gained by the automotive industry in terms of energy storage and designing secondary loads
powered by DC sources can someday be applied to the air mobility market. (Image: iStock)
22
mobilityengineeringtech.com
Using pre-defined parametric models
featuring full-design models and analysis,
developers can customize secondary
power systems quickly. Ideally,
these building block devices are engineered
to meet a range of requirements,
a " superset " of design parameters.
By focusing on the device's
Aerospace & Defense Technology, October 2022

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Aerospace & Defense Technology - October 2022

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