Ship propulsion unit with superconducting coils

2007-Apr-20 | Siemens has developed a new type of ship motor that uses superconductor technology. The propeller unit, which has an output of four megawatts, will be used to power so-called all-electric ships (AES), which will become more and more widespread on the market in the future. Cruise ships, large yachts, and navy ships are already joining the new trend, which has ship propellers being driven by powerful electric motors. The project was presented at the Hanover Trade Fair. All-electric ships offer big benefits when energy requirements fluctuate sharply. Large cruise ships, for example, have to maneuver in a complex manner in order to dock at the many ports they visit, but at other times they generally travel slowly, occasionally speeding up in between. Electric motors can deliver such varying outputs more efficiently and rapidly than diesel engines, which are most economical at constant engine speeds. Passengers benefit as well, because the superconductor motor makes less noise and generates fewer vibrations.

The new development is the result of many years of cooperation between researchers at Corporate Technology and propulsion and shipbuilding experts from other Siemens areas, as well as additional partners from industry and research institutes. Superconducting materials are used for the rotor windings, which is why they are housed in a closed system cooled down to minus 246 degrees Celsius. These windings can bear 100 times more current density than copper windings, which saves weight and space. For example , a generator equipped with superconducting windings already successfully tested by Siemens is only half as heavy and one-fourth as large as a conventional generator. The propulsion unit also produces 30 times more torque (over 300 kilonewtonmeters) than a conventional generator. A comparable electric motor without superconducting coils has a significant lower torque. Like the generator, the motor will be put through its paces at the Siemens System Test Center in Nuremberg in about two years’ time, after which it will be readied for market launch. (IN 2007.04.4)