Abstract High speed ships like the X-Craft, Littoral Combat Ship, and Joint High Speed Vessel are expected to require about 40 MW of propulsion power to achieve the required speed. Today, this power is typically provided through four mechanical drive water jets of about 10 MW each, operating at about 600-rpm. In the future, superconductor technology may enable the Navy to consider electric drive for this application. A notional design has been developed for high speed electric propulsion using four superconductor motors. Each motor would be approximately 1.7 m in diameter, 1.9 m in axial length and ~20,000 kg in weight – it can be built now by using the high-temperature superconductor (HTS) motor technology in development at American Superconductor (AMSC) since the early 1990s. read more

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Abstract A pod propulsion system has been receiving attention as a measure to satisfy the Kyoto Protocol, which was activated in February 2005. A high-temperature superconducting motor is thought to maximize the merit of the pod propulsion system. Sumitomo Electric, University of Fukui, IHI and other organizations have developed the world’s first liquid nitrogen cooled high-temperature superconducting motor for the pod propulsion system. The employed axial gap motor structure is explained by comparing the conventional radial gap motor. The merits of the axial gap motor using high-temperature superconductor are explained. Merits of iron core installation also explained. Two prototype motors have been manufactured and demonstrated. These motor employs commercialized bismuth based read more

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Abstract This paper describes the design of a new kind HTS motor. Superconducting plates used as magnetic screen that cause a spatial variation of the flux density. It is theoretically possible to obtain an air gap flux density variation greater than 3 T. We perform a dimensionless study of the device showing that the torque depends on shape parameters and is limited by the maximum field on the superconducting wire. In the last section, we discuss the performance of the device in term of torque density. Index Terms—Electrical engineering, electromagnetic fields, superconducting rotating machines, synchronous machines. Download read more

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Abstract Superconducting motors have high efficiency as well as reduced size and weight. In superconducting motors, the field winding is composed of HTS tapes (Bi-2223) without any iron core because of magnetic saturation, and the current in the field winding is limited by the maximum magnetic field in the field winding. To enhance the performance of superconducting motor, we need to maximize the critical current of field winding as much as possible. This paper introduces the shape optimization method with the constraint of HTS characteristic ( Ic–B curve), and proposes a shape that improves the critical current of the field winding. Finite element analysis and discrete sensitivity approach are used for calculating the magnetic field of coil and shape optimization. Index read more

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Abstract Studies on ihc application of superconductivity to industrial motors did not take place until the 1970s 1:1]-1:41a, decade after practical, niobium alloy based conductors became available in 1961. The development effort on 10w-T~motors and generators peaked in the late 1970s and enrly 1981)s L51, [GI and continued until k French collaboration recently tested B I50 kW, low speed (400 rpm), permanent magnetic motor with a superconducting armature. The low-Tc tnnterials are limited to operation somewhere below 20 K, and most applications use liquid helium at 4.2 K as the refrigerant. Download read more

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