IEEE Electrification - September 2020 - 61

200 kW drawn from the gird when the ferry is away. In
this case, the power drawn from the grid will be constant. However, in most practical systems, the power
from the grid during charging of the onboard battery is
higher than the power required for recharging the
onshore battery.
For an onboard PMS, there are three states: 1) operating in all-electric mode, 2) operating in hybrid mode (or
emergency mode for all-electric ferries), and 3) charging
from shore. In the first mode, the converter connected
to the onboard battery packs should control not only
the output power of the battery but also the dc bus voltage (since no onboard generators are in operation). In
the second and third modes, converter C32 is only controlling the battery power. Further, to avoid instability
during the charging process in which the onboard dc
bus is connected to the shore bus, two converters
should not be allowed to operate simultaneously with PI
dc-voltage controllers. In the case of directly connected
onboard batteries, there should be a dedicated onshore
dc-dc converter for controlling the charging power,
making the onshore EMS and PMS more complex. During the charging process, monitoring the state of charge
and voltage level of the onboard batteries as well as
start and stop commands are carried out by means of
the onboard PMS.

Conclusion
This article presents a review of current technologies and
future trends for shore-to-ship charging of marine vessels
including power system architectures, charging infrastructure, and control systems for charging management.
Because the electrified vessel fleet is growing rapidly, providing cleaner energy for sea transportation from sustainable sources is a hot topic for research and development
in the marine industry and academia. Shore charging is a
great opportunity to use a land-based grid supported by
renewable energy systems for powering the propulsion of
marine vessels, although it is challenging to charge
onboard batteries within a limited time from a weak grid
available in remote areas.
Three methods for shore to ship charging are
explained: wired charging, wireless charging, and the battery swapping method. In the wired solution, there is a
plug and receptacle, which can be a pantograph or a telescopic arm, etc., to connect the shore power to the ship for
charging its onboard batteries. Depending on whether the
provided shore power is ac or dc, the arrangement and
control objectives of power converters included in the
charging path vary. In the contactless shore-to-ship connection, the electric energy is transferred through the
magnetic field by two coils-the transmitter coil onshore
and the receiver coil onboard. In the last method, the battery swapping method, the depleted batteries exchanged
with the fully charged batteries at port. To have a better
understanding of the practical solutions, some of the

current shore-to-ship charging interfaces have been introduced in this article.
The control strategies used for the battery recharging
process can play a significant role in energy efficiency
enhancement and local grid support. In this regard, an
example of a high-level and a low-level control scheme for
a dc charging system was discussed in the last section.
Based on current and future trends involving the shore-toship charging and the specification of the ship, the proper
choice of power system architecture for the charging system and the control strategy plays an important role for
improving the efficiency and cost of the system.

For Further Reading
P. Ghimire, D. Park, M. K. Zadeh, J. Thorstensen, and E. Pedersen, "Shipboard electric power conversion: System architecture,
applications, control, and challenges," IEEE Electrific. Mag., vol.
7, no. 4, pp. 6-20, Dec. 2019. doi: 10.1109/MELE.2019.2943948.
G. Guidi, J. A. Suul, F. Jenset, and I. Sorfonn, "Wireless charging for ships: High-power inductive charging for battery electric and plug-in hybrid vessels," IEEE Electrific. Mag., vol. 5, no.
3, pp. 22-32, 2017. doi: 10.1109/MELE.2017.2718829.
R. Bosshard and J. W. Kolar, "Inductive power transfer for
electric vehicle charging: Technical challenges and tradeoffs,"
IEEE Power Electron. Mag., vol. 3, no. 3, pp. 22-30, Sept. 2016.
doi: 10.1109/MPEL.2016.2583839.
"Wireless charging," Wartsila, Helsinki, Finland. Accessed
on: Jan. 27, 2020. [Online]. Available: https://www.wartsila
.com/marine/build/power-systems/shore-connections/
wireless-charging
"FerryCHARGER for electric ferries," Stemmann-Technik,
Schüttorf, Germany. Accessed on: Jan. 27, 2020. [Online]. Available: http://www.stemmann.com/en/products/charging
_systems/ferrycharger
"E-CHARGING," Cavotec, Lugano, Switzerland. Accessed on:
Jan. 27, 2020. [Online]. Available: http://www.cavotec.com/en/
your-applications/ports-maritime/e-charging
M. S. Eide, "Charting a course for green coastal shipping,"
DNV GL, Oslo, Norway, 2016. doi: 10.13140/RG.2.2.32516.
94088.
"Analysis of charging- and shore power infrastructure in
Norwegian ports: ReCharge," DNV GL, Oslo, Norway. Accessed
on: Jan. 27, 2020. [Online]. Available: https://www.nek.no/
wp-content/uploads/2019/03/DNV-GL-2017-0101_ReCharge
.pdf
T. W. P. Smith et al., Third IMO GHG Study 2014. London:
International Maritime Organization (IMO), 2014.

Biographies
Siamak Karimi (siamak.karimi@ntnu.no) is with the
Department of Marine Technology, Norwegian University
of Science and Technology, Trondheim.
Mehdi Zadeh (mehdi.zadeh@ntnu.no) is with the
Department of Marine Technology, Norwegian University
of Science and Technology, Trondheim.
Jon Are Suul (jon.are.suul@ntnu.no) is with SINTEF
Energy Research, Trondheim, Norway, and with the
Department of Engineering Cybernetics, Norwegian University of Science and Technology, Trondheim.

IEEE Elec trific ation Magazine / S EP T EM BE R 2 0 2 0

https://www.wartsila.com/marine/build/power-systems/shore-connections/wireless-charging https://www.wartsila.com/marine/build/power-systems/shore-connections/wireless-charging https://www.wartsila.com/marine/build/power-systems/shore-connections/wireless-charging http://www.stemmann.com/en/products/charging_systems/ferrycharger http://www.stemmann.com/en/products/charging_systems/ferrycharger http://www.cavotec.com/en/your-applications/ports-maritime/e-charging http://www.cavotec.com/en/your-applications/ports-maritime/e-charging https://www.nek.no/wp-content/uploads/2019/03/dnv-gl-2017-0101_recharge.pdf https://www.nek.no/wp-content/uploads/2019/03/dnv-gl-2017-0101_recharge.pdf https://www.nek.no/wp-content/uploads/2019/03/dnv-gl-2017-0101_recharge.pdf

IEEE Electrification - September 2020

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