IEEE Electrification Magazine - March 2020 - 39

which is limited by the battery capacity. However, emerging technology for wireless inductive power transfer can
enable autonomy in terms of energy supply, with battery
charging automatically managed by the vehicle without
human intervention. Thus, wireless battery charging can
enable the fully autonomous, long-term operation of electric vehicles.

Wireless Inductive Power Transfer as an
Enabling Technology for Autonomy
Compared to fuel-based vehicles and electric vehicles
with plug-in charging, solutions for wireless inductive
power transfer can be easily automated and facilitate
autonomous battery charging of electric vehicles. After
extensive research and development efforts during the
past two decades, practical solutions for wireless power
transfer are emerging as a convenient, reliable, and flexible technology for battery charging. Although the solutions being commercialized for electric vehicles are
mainly intended for conventional driver-operated cars
and buses, the technology can be utilized by a wide range
of battery-electric autonomous systems.
Indeed, wireless charging is a perfect match for fully
autonomous battery-electric vehicles, and it is easy to
foresee solutions where electric cars with self-driving
capability can manage the charging required to cover their
own energy demand. For this purpose, an autonomous car
could utilize available idling time to drive to the nearest
available wireless charging point and automatically
ensure that the battery would be sufficiently charged
before the next assignment. Such solutions are applicable
to privately owned autonomous cars as well as autonomous taxis and other vehicles that contribute to the public transportation system.
Even with the rapid, ongoing development of electric
vehicles, battery-electric propulsion is considered by a
large part of the general public as unsuitable for long-distance driving due to the limited onboard energy-storage
capability and the time needed for recharging. Although
the limitations of battery capacity, charging time, and driving range might be mainly an issue of cost for privately
owned cars, the weight, size, and charging time of batteries impose significant challenges for the electrification of
commercial vehicles that require long operating ranges
and have few opportunities for battery charging.
One possible approach to avoid the driving-range limitation is to transfer power to the vehicle, for propulsion
and/or battery charging, directly from the road infrastructure during regular operation. Thus, recent research and
development efforts have led to the proposal of several
solutions for "electric road" technology and "roadway-powered electric vehicles." Although conductive solutions
based on sliding contacts are also being developed and
demonstrated, with several concepts being tested in Sweden, solutions for contactless dynamic power transfer have
several advantages in terms of flexibility, safety, and

reliability due to the avoidance of any mechanical and
electrical contact.
The infrastructure for such systems can be embedded
in the road, without any visible interface at the surface.
However, the cost of such solutions is still a significant
challenge, and the technical solutions that have emerged
from the work of different research groups are still not
standardized in a way that can ensure interoperability in
an open environment, such as public roads. Therefore,
several demonstration projects for various concepts that
enable dynamic wireless charging have been initiated or
are currently under development, with the intention to
gain experience while supporting the technology development that is needed before such systems will become
commercially applicable at a larger scale.
Notable activities have, for instance, been initiated in
South Korea, where several concepts for the dynamic or
quasi-dynamic wireless charging of cars, buses, and trains
have been demonstrated. On a smaller scale, several demonstration facilities have been developed for testing technology in controlled environments, for instance, in France
and Italy, within the European Union (EU) Project FABRIC
(FeAsiBility analysis and development of on-Road charging solutions for future electric VehiCles), and at testing
facilities associated with Utah State University. Numerous
other research groups have developed smaller test
facilities for supporting academic and/or industrial
development activities related to the design, control, and
operation of such systems.
Since most demonstration projects have been limited
to relatively low power levels suitable for small vehicles,
only few have studied the infrastructure needed for the
electrification of heavy vehicles by on-road charging. As
one exception, Bombardier in Germany demonstrated a
concept for the dynamic wireless charg-ing of a truck at
power levels of up to 200 kW as part of a Swedish research
project on electric-road technology in 2010-2014. Development has continued in Sweden, and plans for the first
large-scale demonstration of dynamic-charging technology on a public road are being confirmed. The planned system has been under construction since November 2019,
based on technology supplied by the Israeli company Electreon, with an intended commissioning during 2020. This
demonstration project will include 1.4 km of public roads,
and will begin testing with the dynamic wireless charging
of an electric truck, and later on an electric bus.
The existing and planned demonstration projects for
electric-road solutions can be expected to bring the technology forward toward future commercial applications,
but the time required before potential large-scale utilization will be realistic is still uncertain. Although most
research groups involved in the technical developments of
inductive power transfer for electric vehicles are predicting future synergies with self-driving technology, the combined operation of such technologies has not been widely
studied. Thus, a scaled laboratory model that can be
	

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IEEE Electrification Magazine - March 2020

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