Alternating Field Losses in the Superconductor for a Large High-Speed AC Generator

  • M. S. Walker
  • J. H. Murphy
  • Y. W. Chang
  • H. E. HallerIII
Part of the Advances in Cryogenic Engineering book series (ACRE, volume 19)

Abstract

During the past several years, great interest has developed in the use of superconductors in rotating electrical machines. The possible Applications range from low-speed propulsion motors to high-speed airborne generators. Utilization of superconductors frequently offers machines which are of smaller size, lower weight, or higher efficiency. The requirements on the superconducting windings for rotating machinery may be more stringent than for other Applications, however, because of the high current densities which are used, the alternating and/or transient electromagnetic fields in which the windings may operate, and the rates of excitation which field windings must achieve.

Keywords

Bias Field Hysteresis Loss Copper Matrix Persistent Current Eddy Current Loss 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notation

B

= magnetic flux density

Bm

= amplitude of Applied alternating magnetic field

B0

= magnitude of bias magnetic field

d

= diameter of filaments

f

= frequency of Applied field

Jc

= critical current density of filaments

L

= filament twist pitch

P

= power loss at B0

P0

= power loss at B­0 = 0 T

R0

= average radius of composite core

Rt

= average outside radius of wire

RRR

= σi(4.2 K, B0=0)/ σi(300 K, B0=0)

t

= time

V

= volume of sample

Greek symbols

λ

= fraction of composite core that is superconductor

δ

= skin depth in composite core,(πμfσi) 1/2

μ

= average permeability of core, μRμ0

μ0

= Permeability of free space

μr

= isotropic relative permeability of composite core

σ||

= average conductivity parallel to superconducting filaments

σ

= average conductivity transverse to superconducting filaments

ω

= angular frequency of alternating field, 2πf

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References

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Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • M. S. Walker
    • 1
  • J. H. Murphy
    • 1
  • Y. W. Chang
    • 1
  • H. E. HallerIII
    • 2
  1. 1.Westinghouse Research LaboratoriesPittsburghUSA
  2. 2.Westinghouse Electromechanical DivisionCheswickUSA

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