Rotating Machinery Utilizing Superconductors

The properties of superconducting materials appropriate for a discussion of their application in rotating machines are cited. The electrical, mechanical, and thermal losses that will occur in superconducting rotating machines are defined and estimated. The requirements for maintaining the cryogenic environment are given in terms of refrigerant use and in terms of refrigeration. Some estimates are given of refrigerator size and efficiency. The results of a circuit analysis of an alternator are given to define the maximum performance in terms of circuit parameters. The results of an electromagnetic field analysis are used to relate circuit parameters to geometry and material properties. On the basis of these analyses some estimates are made of the specific mass of alternators with superconducting armatures and with ambient temperature armatures. These results are combined with the results of the loss analysis to obtain the overall specific mass and efficiency of each alternator system. Finally, a proposed system is presented for a 1000 kVA turboalternator having a specific mass of 1.85 pounds per kilowatt including the gas turbine, and refrigerator.