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PM technology could save ship-owners €50,000 a month

31 October, 2013

The Switch, the Finnish developer of permanent magnet (PM) motor and generator systems, has entered the marine sector with a “next-generation” drivetrain for powering and propelling vessels efficiently. It says that the combination of PM and frequency converter technologies will allow ship-owners to cut their running costs by up to €50,000 per month.

The technology will allow vessels to produce electricity more efficiently and to cut costs by avoiding the need to run auxiliary generators. The main engines, operating at variable speeds, will be used to generate electricity. The Switch says that the system will lead to substantial savings for vessels with four-stroke – and, in particular, two-stroke – engines and help them to comply with future environmental legislation.

“Soaring fuel prices, global overcapacity and lower profit margins are forcing shipbuilders to rethink conventional power configurations,” says The Switch’s president and CEO, Jukka-Pekka Mäkinen. “This has opened the way for advanced technologies that are revolutionising the way ships generate and use energy for the good of the environment.

“Our drivetrain technology,” he continues, “is a game-changing opportunity for hybrid propulsion systems in the large merchant shipping sector, where two-stroke main engines are the preferred type of prime mover. It will enable ship-owners to save up to €50,000 per month in fuel costs, which may add up to 7% more profit per year.”

Because of their high power densities, PM machines can be smaller and lighter than rival technologies. A frequency converter added to a shaft generator can be used to control a ship’s speed and to ensure a stable source of on-board electricity. Power can be taken from the main engine or from auxiliary generators.

The Switch's marine propulsion and power generation system is based on permanent magnet technology

PM machines offer high efficiencies over their whole operating range, reducing fuel consumption significantly. The Switch claims that they are typically 2-4% more efficient than induction machines at full load, and 10% more efficient at part-loads. These efficiencies result from the absence of current losses in the rotor, the elimination of an exciter, and lower winding losses.

The Switch’s synchronous PM machines use neodymium-iron-boron (NdFeB) rare-earth magnets with a high flux densities, making them ideal for variable-speed generators across the speed range. The magnetic field is created with almost no rotor losses.

The machines’ high power densities lead to smaller and lighter drivetrains, allowing more design flexibility in the limited space available on board ships.

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