Journal ArticleDOI
Dynamic resistance of a high-Tc superconducting flux pump
TLDR
In this article, a mechanically rotating superconducting flux pump was used to excite an HTS double pancake coil at 77 K. This flux pump is found to possess an effective internal resistance, Reff, which varies linearly with frequency, and is two orders of magnitude larger than the measured series resistance of the soldered contacts within the circuit.Abstract:
Superconducting flux pumps enable large currents to be injected into a superconducting circuit, without the requirement for thermally conducting current leads which bridge between the cryogenic environment and room temperature. In this work, we have built and studied a mechanically rotating flux pump which employs a coated conductor high-Tc superconducting (HTS) stator. This flux pump has been used to excite an HTS double pancake coil at 77 K. Operation of the flux pump causes the current within the superconducting circuit to increase over time, before saturating at a limiting value. Interestingly, the superconducting flux pump is found to possess an effective internal resistance, Reff, which varies linearly with frequency, and is two orders of magnitude larger than the measured series resistance of the soldered contacts within the circuit. This internal resistance sets a limit for the maximum achievable output current from the flux pump, which is independent of the operating frequency. We attribute this ...read more
Citations
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Journal ArticleDOI
Mechanism of a high-Tc superconducting flux pump: Using alternating magnetic field to trigger flux flow
Jianzhao Geng,Tim Coombs +1 more
TL;DR: In this article, the authors proposed a flux pumping mechanism for high-tc superconducting (HTS) coils with an experimental verification and an analytical model, where the basic principle is that flux flow can be triggered when the superconductor carrying a direct current is subjected to a perpendicular AC magnetic field.
Journal ArticleDOI
Development of a brushless HTS exciter for a 10 kW HTS synchronous generator
Chris W. Bumby,Rodney A. Badcock,Hae-Jin Sung,Kwangmin Kim,Zhenan Jiang,A. E. Pantoja,Patrick Bernardo,Patrick Bernardo,Minwon Park,R. G. Buckley +9 more
TL;DR: In this article, a brushless HTS-PM exciter is proposed to inject a superconducting DC current into the rotor coil circuit, which can significantly alter the thermal load upon the cryogenic system by removing the need for thermally inefficient normalconducting current leads.
Journal ArticleDOI
Impact of flux gap upon dynamic resistance of a rotating HTS flux pump
TL;DR: In this article, the effect of varying the size of the flux gap between the rotor magnets and coated conductor stator from 1 to 7.5 mm was investigated and it was shown that the performance of an experimental mechanically rotating HTS flux pump ceases to maintain a measurable output at flux gaps above 7.
Journal ArticleDOI
Anomalous open-circuit voltage from a high-Tc superconducting dynamo
TL;DR: In this article, a high-Tcsuperconducting (HTS) homopolar dynamo which outputs a DC open-circuit voltage when the stator is in the superconducting state, but behaves as a conventional AC alternator when in the normal state is observed, which is attributed to screening currents in the HTS stator wire.
Journal ArticleDOI
Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K
TL;DR: In this paper, the dynamic resistance of superconducting high-T c coated conductor (CC) wires was measured in an AC perpendicular field and an analytical expression was derived for the threshold field at zero transport current.
References
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Journal ArticleDOI
Critical persistent currents in hard superconductors
TL;DR: In this paper, the authors investigated persistent currents induced in hard superconductors (HSC) by measuring the resulting magnetic effects and found that the Lorentz force plays a crucial role in determining the critical current density and the critical persistent currents in decay with a measurable rate.
Book
Applications of High Temperature Superconductors to Electric Power Equipment
TL;DR: In this paper, the authors present an overview of the properties of superconducting field windings and their application in the context of cooling and cooling of high-speed motors, as well as a discussion of the challenges involved in the design of such systems.
Journal ArticleDOI
Fully superconducting rectifiers and fluxpumps Part 1: Realized methods for pumping flux
TL;DR: In the past twenty years, a large variety of mechanically or electrically driven devices have been proposed and successfully operated and the basic principle of operation of each class of devices is shown and specific material problems and limitations are reported as mentioned in this paper.
Journal ArticleDOI
Flux Pump for HTS Magnets
C Hoffmann,D Pooke,A.D. Caplin +2 more
TL;DR: In this paper, a flux pump based on 2G HTS wire is presented, which can achieve a critical current of 49 A within 112 seconds, which is a state-of-the-art performance for superconducting devices.
BookDOI
Applications of High Temperature Superconductors to Electric Power Equipment: Kalsi/Applications of High Temperature Superconductors
TL;DR: In this article, the authors present an overview of the properties of superconducting field windings and their application in the context of cooling and cooling of high-speed motors, as well as a discussion of the challenges involved in the design of such systems.
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Mechanism of a high-Tc superconducting flux pump: Using alternating magnetic field to trigger flux flow
Jianzhao Geng,Tim Coombs +1 more