AC Losses of YBCO Coated Conductor with Ferromagnetic Substrate in DC Field

2013 ◽  
Vol 745-746 ◽  
pp. 191-196
Author(s):  
Guo Min Zhang ◽  
Zhen Ling Xu ◽  
Hui Yu ◽  
Jin Cheng Li
Keyword(s):  
Magnetic Fields ◽  
Nickel Alloy ◽  
Loss Factor ◽  
Coated Conductors ◽  
Ac Loss ◽  
Ac Losses ◽  
Coated Conductor ◽  
Background Magnetic Field ◽  
Repressive Effect ◽  
Transport Loss

As YBCO coated conductors are usually prepared on nickel or nickel alloy substrates, additional ferromagnetic losses are generated in the substrates when the conductors are exposed to AC magnetic fields or carrying alternative currents in practical application. In this work, AC transport loss factors of YBCO tapes with Ni-W alloy substrates were studied in DC magnetic fields. The influence of ferromagnetic substrate on AC loss and the repressive effect of DC background magnetic field on ferromagnetic loss in the substrate were presented and analyzed. The results showed that the AC transport loss factor of YBCO tape with Ni-W substrate decreased gradually with the increasing background field, and the minimum value of AC loss factor appeared as the field reach to about 18 mT and 45 mT for parallel and perpendicular applied field respectively. Based on the analysis, the method to reduce AC transport current loss in coated conductor with nickel alloy substrate is proposed.

Observations from the Analyses of Magnetic Field and AC Loss Distributions in the NHMFL 32 T All-Superconducting Magnet HTS Insert

2013 ◽  
Vol 23 (3) ◽  
pp. 4300704-4300704 ◽  
Author(s):  
Andrew Gavrilin ◽  
Jun Lu ◽  
Hongyu Bai ◽  
David Hilton ◽  
W Markiewicz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Superconducting Magnet ◽  
Coated Conductors ◽  
Ac Loss ◽  
Ac Losses ◽  
Magnet System ◽  
Field Gradients ◽  
The Magnetic Field ◽  
Helium Vapor

A 17 T high-temperature superconducting two-coil magnet (insert) to be operated in a 15 T low-temperature superconducting multisection magnet (outsert) is the most demanding part of the National High Magnetic Field Laboratory all-superconducting 32 T magnet system. The HTS coils are of the pancake type and to be wound with REBCO coated conductors/tapes manufactured by SuperPower, Inc. The distribution of AC losses in the HTS windings during the magnet charging/discharging process are computed and analyzed with due regard for the AC loss density dependence on the magnetic field and the field angle. The calculations are based on the measured magnetization of a representative sample against magnetic field and field angle. The results enable determination of heat load on the magnet and its cryogenic system. Since the magnet is of the pool-cooled type, a related helium vapor bubble problem can develop owing to the high field and field gradients, and the diamagnetic susceptibility of helium.

AC Loss Characteristics of Stacks of YBCO Coated Conductors

2006 ◽  
Vol 946 ◽  
Author(s):  
Francesco Grilli ◽  
Stephen P. Ashworth ◽  
Svetlomir Stavrev
Keyword(s):  
Magnetic Field ◽  
Transport Current ◽  
Point Of View ◽  
Coated Conductors ◽  
Ac Loss ◽  
Ac Losses ◽  
Practical Applications ◽  
Superconducting Coils ◽  
Loss Characteristic ◽  
Ybco Coated Conductors

ABSTRACTPractical applications of YBCO coated conductors (CC) involving superconducting coils will utilize tapes packed together in an arrangement resembling a vertical stack. In such configuration there is an important electromagnetic interaction between the tapes, which strongly influences the loss characteristic of the device.In the presence of an external magnetic field, the losses are reduced compared to an isolated tape because of the reduced aspect ratio of the conductor and, at least for low fields, because of an effective screening of the central part of the stack. On the contrary, in the case of AC transport current, the losses tend to increase due to the enhancement of the local field caused by the interaction of the self-field produced by neighboring tapes. In practical situations the conductor is usually subjected to both transport current and magnetic field, so that there is a trade-off between the two effects.In this paper we investigate, both experimentally and by means of finite-element method calculations, the ac loss behavior of a stack composed by a finite number of tapes in different working conditions, and we compare the AC losses to the ones of non-interacting tapes in order to determine if the use of stacked tapes is advantageous from the point of view of power dissipation.

scholarly journals Numerical modelling of dynamic resistance in high-temperature superconducting coated-conductor wires

2021 ◽  
Author(s):  
MD Ainslie ◽  
Christopher Bumby ◽  
Zhenan Jiang ◽  
R Toyomoto ◽  
N Amemiya
Keyword(s):  
Magnetic Fields ◽  
Angular Dependence ◽  
Flow Resistance ◽  
Transport Current ◽  
Ac Loss ◽  
Dynamic Resistance ◽  
Coated Conductor ◽  
Superconducting Properties ◽  
Flux Flow ◽  
The Wire

The use of superconducting wire within AC power systems is complicated by the dissipative interactions that occur when a superconductor is exposed to an alternating current and/or magnetic field, giving rise to a superconducting AC loss caused by the motion of vortices within the superconducting material. When a superconductor is exposed to an alternating field whilst carrying a constant DC transport current, a DC electrical resistance can be observed, commonly referred to as ‘dynamic resistance.’ Dynamic resistance is relevant to many potential hightemperature superconducting (HTS) applications and has been identified as critical to understanding the operating mechanism of HTS flux pump devices. In this paper, a 2D numerical model based on the finite-element method and implementing the H-formulation is used to calculate the dynamic resistance and total AC loss in a coated-conductor HTS wire carrying an arbitrary DC transport current and exposed to background AC magnetic fields up to 100 mT. The measured angular dependence of the superconducting properties of the wire are used as input data, and the model is validated using experimental data for magnetic fields perpendicular to the plane of the wire, as well as at angles of 30° and 60° to this axis. The model is used to obtain insights into the characteristics of such dynamic resistance, including its relationship with the applied current and field, the wire’s superconducting properties, the threshold field above which dynamic resistance is generated and the flux-flow resistance that arises when the total driven transport current exceeds the field-dependent critical current, Ic(B), of the wire. It is shown that the dynamic resistance can be mostly determined by the perpendicular field component with subtle differences determined by the angular dependence of the superconducting properties of the wire. The dynamic resistance in parallel fields is essentially negligible until Jc is exceeded and flux-flow resistance occurs.

Transport AC Losses of YBCO Coated Conductor Coils

2007 ◽  
Vol 1001 ◽  
Author(s):  
Francesco Grilli ◽  
Stephen P. Ashworth
Keyword(s):  
Coated Conductors ◽  
Ac Losses ◽  
Coated Conductor ◽  
Superconducting Tapes ◽  
Practical Applications ◽  
Superconducting Tape ◽  
Ybco Coated Conductor ◽  
The Magnetic Field ◽  
Ybco Coated Conductors ◽  
Transport Ac Losses

AbstractCertain practical applications of YBCO coated conductors (CC) involve superconducting tapes wound in coils. In such a configuration the superconducting tape is arranged as closely packed turns, leading to an increase of the magnetic field generated by the current in the tapes and, consequently, a significant increase in the AC losses, with respect to an ‘isolated’ tape. In order to predict and reduce the refrigeration requirements of applications, it is therefore very important to be able to quantify the magnitude of such AC losses, both experimentally and by means of numerical calculations.

Concepts for HTS and MgB2 in Transformers

2006 ◽  
Vol 47 ◽  
pp. 195-203 ◽  
Author(s):  
Pascal Tixador
Keyword(s):  
Low Cost ◽  
Point Of View ◽  
Coated Conductors ◽  
Ac Loss ◽  
Mobile Systems ◽  
Ac Losses ◽  
Magnetic Flux Density ◽  
Price Performance ◽  
Substantial Progress ◽  
Lower Temperature

After the emergence of AC NbTi strands, superconducting transformers were successfully built. But the very high cost of 4 K cryogenics made these transformers economically not attractive. The high Tc superconductors (HTS), operating at much higher temperatures, change these conclusions with low cost HTS conductors. The high cost of PIT tapes and the relatively large AC losses remain issues. The second generation HTS wires, the REBCO coated conductors, are under development and achieved substantial progress recently. They operate at higher temperatures and intrinsically show lower AC losses especially for transformers. MgB2 is the third option. The magnetic flux density conditions make possible the operation at 27 K and they show low costs. This paper provides a preliminary design for an on-board 40 MVA transformer using YBCO coated conductors and MgB2 wires. Both superconducting transformers show similar volume and weight. The power density per unit mass and volume is improved by a factor about two, cryogenic included, compared to resistive systems. This makes them very attractive for on-board mobile systems. The economical point of view will be discussed based on some targets price/performance for superconductors and cryocoolers. MgB2 is penalized by its operation at lower temperature (27 K / 77 K), which makes cryogenics very expensive. The advantage of the low cost of MgB2 compared to REBCO may be lost except with very low AC loss MgB2 tapes.

scholarly journals AC losses of no-insulation high temperature superconductor (RE)Ba2Cu3Ox coils induced by ripple magnetic fields in machines

2020 ◽  
Author(s):  
Yawei Wang
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
High Temperature Superconductor ◽  
Eddy Currents ◽  
Ac Loss ◽  
Ac Losses ◽  
Induced Current ◽  
Risk Optimization ◽  
Current Flows ◽  
The Stability

<p>No-insulation high temperature superconductor (NI HTS) (RE)Ba2Cu3Ox coil technology is effective in enhancing the thermal stability of HTS coils. Applying the NI technique on the rotor windings of HTS machines can improve the stability and reliability of the machines. However, the NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through the turn-to-turn contacts. The accompanying turn-to-turn losses will considerably affect the machine efficiency. In this study, we compared experimentally the losses of NI HTS coils subjected to external AC magnetic fields with those of insulated coils. Measurement system based on calibration-free method is developed for the AC loss measurement on HTS coils exposed to external AC magnetic fields. The results show that the AC loss of NI HTS coils can be 20 times higher than that of insulated HTS coils, and lowering turn-to-turn resistivity can significantly reduce this AC loss. Modeling analysis shows that most of induced current flows in the outer turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher induced current in superconducting layers and more significant accumulation of turn-to-turn loss. This will increase quench risk. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments. </p>

Ac loss in YBCO coated conductors exposed to external magnetic fields at 50–200Hz

2007 ◽  
Vol 466 (1-2) ◽  
pp. 29-36 ◽  
Author(s):  
M.D. Sumption ◽  
S. Kawabata ◽  
E.W. Collings
Keyword(s):  
Magnetic Fields ◽  
Coated Conductors ◽  
Ac Loss ◽  
Ybco Coated Conductors

Experimental Study on AC Loss of a Quasi-Isotropic Strand Fabricated by Coated Conductors in AC Magnetic Fields

2018 ◽  
Vol 28 (3) ◽  
pp. 1-6 ◽  
Author(s):  
Yan Li ◽  
Yinshun Wang ◽  
Changtao Kan ◽  
Mingchuang Liu ◽  
Hao Chen ◽  
...  
Keyword(s):  
Experimental Study ◽  
Magnetic Fields ◽  
Coated Conductors ◽  
Ac Loss

scholarly journals Effect of Substrate Layer Thickness on the AC Losses in Stacked Superconducting Pancake Coils using Direct H-formulations

2019 ◽  
Vol 9 (1S3) ◽  
pp. 150-154
Keyword(s):  
High Speed ◽  
Volume Fraction ◽  
Substrate Material ◽  
Coated Conductors ◽  
Ac Loss ◽  
Ac Losses ◽  
2Nd Generation ◽  
Electric Aircraft ◽  
Commercial Software Package ◽  
Pancake Coils

Advanced electric aircrafts are in their design phase and superconducting machines are going to be the part of such fascinating technology. In order to diminish the losses involved due to conventional copper conductors, superconductors are proposed for the electric aircraft applications by the American research agencies like NASA and AFRL. Usually, Pancake coils are frequently used in various electric aircraft power applications including high speed motors, generators, transformers and solenoid magnets. Coils are generally bound with high temperature superconducting (HTS) tapes like BSCCO and YBCO. Mostly, 2nd generation coated conductors (YBCO) are employed in power applications due to their merits over BSCCO (1st generation tapes). A superconducting tape manufactured by SuperPower through iBAD manufacturing technique generally consist copper stabilizer, silver over-layer, YBCO layer, buffer layer, substrate material followed by copper stabilizer. The volume fraction of the substrate material and copper stabilizer is more than 90% in the proposed tape. In the present work, the thickness of the substrate material has been varied to evaluate the AC losses involved in the above mentioned applications due to time-varying magnetic fields. A current of 270 A (Ic=330 A) is flowing through a coil of 108 turns. AC loss has been evaluated for various thicknesses 30 µm to 90 µm at a frequency of 50 Hz. The simulations are done using COMSOL MultiPhysics® commercial software package.

scholarly journals AC losses of no-insulation high temperature superconductor (RE)Ba2Cu3Ox coils induced by ripple magnetic fields in machines

2020 ◽  
Author(s):  
Yawei Wang
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
High Temperature Superconductor ◽  
Eddy Currents ◽  
Ac Loss ◽  
Ac Losses ◽  
Induced Current ◽  
Risk Optimization ◽  
Current Flows ◽  
The Stability

<p>No-insulation high temperature superconductor (NI HTS) (RE)Ba2Cu3Ox coil technology is effective in enhancing the thermal stability of HTS coils. Applying the NI technique on the rotor windings of HTS machines can improve the stability and reliability of the machines. However, the NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through the turn-to-turn contacts. The accompanying turn-to-turn losses will considerably affect the machine efficiency. In this study, we compared experimentally the losses of NI HTS coils subjected to external AC magnetic fields with those of insulated coils. Measurement system based on calibration-free method is developed for the AC loss measurement on HTS coils exposed to external AC magnetic fields. The results show that the AC loss of NI HTS coils can be 20 times higher than that of insulated HTS coils, and lowering turn-to-turn resistivity can significantly reduce this AC loss. Modeling analysis shows that most of induced current flows in the outer turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher induced current in superconducting layers and more significant accumulation of turn-to-turn loss. This will increase quench risk. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments. </p>

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