It is said that extensive CO2 emissions is a well-known cause for the crucial temperature rise the Earth is experiencing, so all people of the world need to devise a good way to reduce global CO2 emissions. One mean is to utilize some technologies to improve the efficiency of electrical equipment, such as that used for electric- power generation and power machinery. One of the most effective technologies is thought to be the application of high-temperature superconductivity so as to improve energy conversion efficiency based on the zero resistivity of superconductive winding conductors, together with the use of low iron loss magnetic materials. This paper clarifies a theoretical design philosophy for high-efficiency, small-size and lightweight electric rotating machinery, and reports on a surveyof the current status of R&D regarding high-temperature superconducting (HTS) electric rotating machinery. In addition, the paper discusses observations regarding the ulterior solvents for successfully and actually manufacturing HTS electric machinery.
The research and development conducted regarding fully superconducting motors for liquid-hydrogen transfer pumps using MgB2 monofilamentary wires are gathered into this paper. Synchronous rotation without slip can be realized using squirrelcage-type rotor windings composed of quasi-superconducting loops soldered between MgB2 wires, thereby enabling superconducting motors with low loss and high efficiency to be achieved. The use of MgB2 wires for stator windings also enables the primary winding loss to be reduced drastically compared to conventional copper winding. The transfer of liquid hydrogen from a metal cryostat containing the fabricated MgB2 motor to a glass Dewar vessel for visual monitoring is demonstrated successfully.
Recently, practical applications of high-temperature superconducting (HTS) wires are being promoted. Superconducting motor is one of the application for HTS wires, with the advantage of expected higher efficiency. As the performance of the wire was improved, the development of a superconducting motor has been actively conducted. To demonstrate the higher efficiency of electric vehicles driven by a superconducting motor, the d