Influence of DC Offset Transport Current on AC Loss Characteristics in HTS Tapes

Ogawa, J.; Fukui, Satoshi; Oka, Tetsuo; Satô, Takao; Kojima, H.; Shibayama, Motoaki; Egawa, Mariko

doi:10.1109/tasc.2010.2088099

Cited by 11 publications

(16 citation statements)

References 8 publications

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“…When the DC transport current is over 15 A and the AC transport current is small, the total loss is higher than the AC transport current loss. In previous experiments, a single HTS tape loss with AC and DC transport current exceeded the AC transport current loss characteristic when the peak of the AC and DC transport current exceeded the critical current of HTS tape [8]. In Fig.…”

Section: A Frequency Dependency Of Ac Transport Current Loss In the mentioning

confidence: 65%

“…However, the HTS tapes in an HTS coil transport AC and DC offset current through an AC and DC magnetic field produced by the current in neighboring tapes. We previously reported our observations on the loss from HTS tape in an AC and DC mixed electro-magnetic condition which consists of the DC offset transport current, AC transport current and the AC magnetic field [8] were measured in the same segment by the electric and calorimetric methods, and we established the possibility of measuring the loss using the electric method in the AC and DC mixed electro-magnetic condition. These results confirm that DC transport current affects the loss characteristics in an AC and DC mixed electro-magnetic condition.…”

Section: Introductionmentioning

confidence: 99%

“…The AC and DC offset transport current is provided by a bipolar power supply. The AC and DC offset voltages are measured using a lock-in amplifier and digital voltmeter, respectively [8]. The voltage includes a large AC inductive voltage for the loss measurement, and the inductive voltage is canceled by the cancel coil voltage which is placed in the center of the pancake coil.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of Loss Characteristics With AC and DC Offset Transport Current in HTS Double Pancake Coil

Ogawa

Fukui

Oka

et al. 2012

IEEE Trans. Appl. Supercond.

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Many papers report the AC transport current loss characteristics in HTS coils, which occur because the HTS tapes in the coil transport a current in a magnetic field generated by the currents in adjacent tapes. We previously reported our experimental results on the loss from HTS tape in an AC and DC mixed electro-magnetic condition which consists of the DC offset transport current, AC transport current and AC magnetic field. Losses were measured in the same segment by the electric and calorimetric methods, and we established the possibility of measuring the loss using the electric method in the AC and DC mixed electro-magnetic condition. Now, we report the loss characteristics with AC and DC offset transport current in an HTS double pancake coil. We measured the AC and DC loss components by a four-terminal method. The voltage from the HTS coil includes the large AC inductive voltage, and we canceled the inductive voltage using a cancel coil placed in the center of the HTS coil. We report our findings on the loss characteristics in an HTS coil with AC and DC offset current in the HTS coil.Index Terms-AC and DC offset transport current, AC transport current loss, DC loss component, HTS double pancake coil.

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Section: A Frequency Dependency Of Ac Transport Current Loss In the mentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Investigation of Loss Characteristics With AC and DC Offset Transport Current in HTS Double Pancake Coil

Ogawa

Fukui

Oka

et al. 2012

IEEE Trans. Appl. Supercond.

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“…The main advantage of using this geometry for the numerical modelling of type-II superconductors, relies on the possibility to compare the numerical results with exact or semi-analytical approaches, what allows a direct grasp of the physics involved whilst a phenomenological benchmark for the implementation of practical applications is being developed. In fact, the simple notion of this 2D geometry, i.e., by assuming that the length of the SC wire is much greater than its radius, and the critical state theory for the macroscopic modelling of the electromagnetic properties of type-II SCs [5][6][7][8], has allowed to predict and explain multitude of experimental phenomena including but not limited to, the magnetization and demagnetization of SCs under crossed and rotating magnetic field experiments [9][10][11][12][13], the low pass filtering effect in the magnetic moment of AC SC wires [14], and strong patterns of localization of the density of power losses inside the SC materials under magnetic and electrical stress conditions [15,16].…”

Section: Introductionmentioning

confidence: 99%

Magnetic characteristics and AC losses of DC type-II superconductors under oscillating magnetic fields

Robert

2018

Supercond. Sci. Technol.

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Remarkable features on the magnetic moment of type-II superconducting wires of cylindrical shape, subjected to direct current conditions (DC) and transverse oscillating (AC) magnetic fields, are reported. We show how for relatively low amplitudes of the applied magnetic field, Ba, the superconducting wire rapidly develops a saturation state, |Mp|, characterizing the limits of magnetization loops that exhibit a Boolean-like behaviour. Regardless of the premagnetization state of the superconducting wire, we show how after two cycles of magnetic relaxation, boolean-like ±Mp states can be measured during the entire period of time from which the external magnetic field B0 ranges from 0 to ±Ba, with the signs rule defined by the sign of the slope ∆B0y(t). In addition, for the practical implementation of superconducting DC wires sharing the right of way with AC lines, we report that for relatively low values of magnetic field, Ba ≤ BP /2, being BP the analytical value for the full penetration field in absence of transport current, Itr, the use of semi-analytical approaches for the calculation of AC-losses leads to a significant underestimation of the actual contribution of the induction losses. This phenomena is particularly relevant at dimensionless fields ba < 1 − i 2/3 a , being ba = Ba/BP and, ia = Ia/Ic the amplitude of an AC or DC transport current, due to the local motion of flux front profiles being dominated by the occurrence of transport current. On the other hand, we have found that regardless of the nature of the transport current, either be DC or AC, when a transverse oscillating magnetic field greater than the classical limit ba = (1 − ia) is applied to the SC wire, the difference between the obtained AC losses in both situations results to be negligible indistinctly of the approach used, semi-analytical or numerical. Thus, the actual limits from which the estimation of the AC-losses can be used as an asset for the deployment of DC SC wires sharing the right of way with AC lines, against the sole use of SC wires for the transmission of AC transport current, are established.

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“…On the other hand, the ac ripple current, i.e., ac current with dc offset, of the dc/dc converter generates ac losses in the HTS coil. Although recent studies experimentally investigated the ac losses in HTS coils under ac currents with dc offsets [10]- [12], these losses have not been sufficiently investigated by analyses based on a physically oriented current transport model of HTS tapes. Moreover, since the spacecraft has the limitation of the HTS cooling system due to the mass limit, the ac loss can be a serious constraint to design the HTS coil system for the space applications.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on Thermal Stability of Conduction-Cooled Bi-2223/Ag Coil Under AC Ripple Current for Space Applications

Nagasaki

Nakamura

Funaki

et al. 2014

IEEE Trans. Appl. Supercond.

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This study investigated the transport ac loss in a high-temperature superconducting (HTS) coil under ac ripple currents with dc offsets for space applications of the HTS coil. We developed an analysis method to evaluate the effective ac loss in the HTS coil on the basis of the percolation depinning model. Our analysis clarified that larger dc offsets greatly increase the effective ac loss even under a smaller ac current. In addition, we investigated the effect of the ac loss with the ripple current on the thermal behavior of a conduction-cooled Bi-2223/Ag coil. As a result, the ac loss decreased the thermal stability of the conduction-cooled coil in case that HTS tapes in the coil are in the flux-flow state such as the load factor of 80%. However, at a lower load factor such as less than 60%, the ripple current did not have much effect on the thermal stability of the conduction-cooled coil because most of the ac power were consumed as a reactive power. These results suggested that, in order to apply the ac ripple current to HTS coils, the operational load factor must be properly selected. This study leads to a design of the light-weight HTS coil system for space missions.

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Influence of DC Offset Transport Current on AC Loss Characteristics in HTS Tapes

Cited by 11 publications

References 8 publications

Experimental Investigation of Loss Characteristics With AC and DC Offset Transport Current in HTS Double Pancake Coil

Experimental Investigation of Loss Characteristics With AC and DC Offset Transport Current in HTS Double Pancake Coil

Magnetic characteristics and AC losses of DC type-II superconductors under oscillating magnetic fields

Numerical Investigation on Thermal Stability of Conduction-Cooled Bi-2223/Ag Coil Under AC Ripple Current for Space Applications

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