TY - JOUR
T1 - Modeling of Stator Versus Magnet Width Effects in High-Tc Superconducting Dynamos
AU - Mataira, Ratu
AU - Ainslie, Mark D.
AU - Badcock, Rod
AU - Bumby, Chris W.
N1 - Funding Information:
Manuscript received September 24, 2019; accepted February 17, 2020. Date of publication March 9, 2020; date of current version March 27, 2020. This work was supported in part by New Zealand MBIE Endeavour under Grant RTVU1707 and in part by NZ Royal Society Marsden Award under Grant MFP-VUW1806. The work of M. D. Ainslie was supported by the Engineering and Physical Sciences Research Council (EPSRC) Early Career Fellowship under Grant EP/P020313/1. (Corresponding author: Ratu Mataira.) Ratu Mataira, Rod Badcock, and Chris W. Bumby are with the Robinson Research Institute, Victoria University of Wellington, Lower Hutt 5046, New Zealand (e-mail: [email protected]; [email protected]).
Funding Information:
This work was supported in part by New Zealand MBIE Endeavour under Grant RTVU1707 and in part by NZ Royal Society Marsden Award under Grant MFPVUW1806. The work of M. D. Ainslie was supported by the Engineering and Physical Sciences Research Council (EPSRC) Early Career Fellowship under Grant EP/P020313/1.
Publisher Copyright:
© 2020 IEEE.
PY - 2020/3/9
Y1 - 2020/3/9
N2 - High-Tc superconducting (HTS) dynamos are simple devices for injecting and sustaining dc currents in superconducting coils/magnets. The simple geometry of these devices consists of a superconducting stator(s) and one or more rotor magnets arranged in identical fashion to a classical alternator. However, unlike the classical alternator, the HTS dynamo gives a self-rectified dc output. This somewhat anomalous result is caused by the non-linear resistivity of HTS materials and the large over-critical eddy currents that flow in the stator. As these over-critical currents must recirculate in the HTS stator, the stator's width becomes a key parameter in the physics of the device. In this work we explore the effect of increasing the stator width through using recent advances in modeling these systems. We find that given enough space in the stator, the total sum of circulating and transport currents do not drive the full width of the stator into the flux-flow regime. Operation of the device in this regime results in a non-linear I-V curve, a marked decrease in the internal resistance at open circuit Roc, a saturation of the open circuit voltage Voc, and a short-circuit current Isc that approaches the in-field critical current of the stator itself Ic,min. These behaviors lead to the conclusion that optimal HTS dynamo design should ensure that the stator width be sufficient to avoid current saturation of the superconductor at the target operating current.
AB - High-Tc superconducting (HTS) dynamos are simple devices for injecting and sustaining dc currents in superconducting coils/magnets. The simple geometry of these devices consists of a superconducting stator(s) and one or more rotor magnets arranged in identical fashion to a classical alternator. However, unlike the classical alternator, the HTS dynamo gives a self-rectified dc output. This somewhat anomalous result is caused by the non-linear resistivity of HTS materials and the large over-critical eddy currents that flow in the stator. As these over-critical currents must recirculate in the HTS stator, the stator's width becomes a key parameter in the physics of the device. In this work we explore the effect of increasing the stator width through using recent advances in modeling these systems. We find that given enough space in the stator, the total sum of circulating and transport currents do not drive the full width of the stator into the flux-flow regime. Operation of the device in this regime results in a non-linear I-V curve, a marked decrease in the internal resistance at open circuit Roc, a saturation of the open circuit voltage Voc, and a short-circuit current Isc that approaches the in-field critical current of the stator itself Ic,min. These behaviors lead to the conclusion that optimal HTS dynamo design should ensure that the stator width be sufficient to avoid current saturation of the superconductor at the target operating current.
KW - coated conductor
KW - current leads
KW - Flux pump
KW - HTS dynamo
KW - superconducting generator
KW - YBCO
UR - http://www.scopus.com/inward/record.url?scp=85082809475&partnerID=8YFLogxK
U2 - 10.1109/TASC.2020.2979391
DO - 10.1109/TASC.2020.2979391
M3 - Article
AN - SCOPUS:85082809475
SN - 1051-8223
VL - 30
JO - IEEE Transactions on Applied Superconductivity
JF - IEEE Transactions on Applied Superconductivity
IS - 4
M1 - 5204406
ER -