Wireless Charging On The Water

By BO SVENSSON

The first commercial ferry in the world operating with high power wireless charging capability for its batteries has been successfully tested by Wärtsilä.

The project potentially represents a breakthrough in the evolution of plug-in electrically operated vessels, Wärtsilä said. “The tests were carried out on the 85 m MF Folgefonn in Norwegian waters in early September. The ferry is owned by Norled, one of Norway’s largest ferry operators.

MF Folgefonn is a fully commercial ferry in normal operation and is at present, operating in a plug-in hybrid configuration. It can be run in diesel-electric mode and well as fully electric.

The double ended car ferry was converted in 2014 from a diesel-electric ferry to a plug-in hybrid and plug-in all-electric vessel. The technology demonstration has undergone testing during normal operation for more than a year.

Wärtsilä’s contribution to the MF Folgefonn project was the concept development, including the inverter systems, hybrid control, battery package and systems, power transfer and land-based energy storage system as well as the integration of the onboard systems.

The ferry is equipped with four 500 kW diesel generator sets, complemented by a 1 MWh battery system, which is charged through a plug-in device from shore. The two electrically controlled propulsion motors are each rated 750 kW. As the next step, Wärtsilä has successfully tested its automatic wireless induction charging system on the hybrid powered coastal ferry.

“During recent years, wireless charging has been introduced for cars, buses and trains,” said Ingve Sørfonn, senior technical officer, Electrical & Automation Services, Wärtsilä Marine Solutions. “We have now made this possible for marine vessels.

“The main benefits for customers are up to 20% more utilization of the available charging time, increased operational safety and greater system reliability. There is an ongoing trend to equip coastal ferries with battery powered and hybrid propulsion, since they are particularly affected by environmental regulatory demands. Wireless charging will, therefore, create considerable value for operators of hybrid ferries.”

Wireless charging eliminates the cable connection between the vessel and shore, thereby securing and facilitating safe connections and disconnections. It also reduces maintenance, as wear and tear to physical connection lines is eliminated. The integrated Wärtsilä system is based on inductive power transfer and is capable of transferring more than 1 MW of electrical energy.

Inductive or wireless charging, uses an electromagnetic field to transfer energy between two coils. A sending induction coil is used to create an alternating electromagnetic field and a second induction coil takes the power from the electromagnetic field and converts it back into electric energy. To manage longer distances between sender and receiver coils, the inductive charging system uses resonant inductive coupling.

The Wärtsilä system is designed to maintain efficient power transfer at distances of a half-meter between the two charging plates. The sending charging plate is carried by a robotic arm on the quay, with the receiving charging plate position on the quay side of the vessel. No other wireless charging system is as powerful, or capable of maintaining the transfer of energy at such a distance, Wärtsilä said.

“For Wärtsilä, this wireless charging revolution focuses on coastal ferries, a segment of the transportation industry that is well-suited to the technology because of short stop-and-go schedules,” said Cato Esperø, sales director, Wärtsilä Norway. “The wireless charger is an innovative and value-adding new part of our hybrid solutions offering, which we shall continue to develop further in line with the needs of our customers.”

The project has been partly supported by Innovation Norway, a Norwegian funding institution.

For more on electrification and hybrids visit www.newpowerprogress.