AC loss properties in YBCO model coils for loss reduction

Okamoto, Hiroshi; Hayashi, H.; Tomioka, Akihiro; Konno, Masayuki; Owa, Misa; Kawagoe, A.; Sumiyoshi, F.; Iwakuma, Masataka; Suzuki, Kenji; Izumi, Teruo; Yamada, Yutaka; Shiohara, Yuh

doi:10.1016/j.physc.2008.05.185

Cited by 16 publications

(6 citation statements)

References 1 publication

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“…YBCO coils carrying AC currents with industrial frequencies can be wound with relatively wide YBCO tapes (4 to 12 mm) or the tapes can be divided into several stripes to reduce the total AC losses. However, the results presented in [5] indicate that I-V curves of coils using striated tapes show quite flat I-V curves, hence the power is also dissipated at current far below the critical current of the tape. Ishiguri and Funamoto proposed a graded coil with improved critical current [6].…”

Section: Introductionmentioning

confidence: 92%

Magnetic Field in the Winding of an YBCO Pancake Coil: Experiments and Calculations

Polák

Pardo

Mozola

et al. 2012

IEEE Trans. Appl. Supercond.

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The AC loss is an important issue for many applications containing coils of ReBCO coated conductors, specially transformers. In order to reduce the AC loss, it is necessary to understand the loss mechanisms. We measured and computed the radial magnetic field component in a pancake coil with a net transport current, as this component of the magnetic field plays a crucial role in the AC loss. For this purpose, we prepared a small pancake coil wound with 12 mm wide YBCO tape with non-magnetic substrate and measured the radial component of the magnetic field in the space between turns at both 77 K and room temperature. We measured at six radial positions inside the coil winding during the first AC cycle and the following ones. Additionally, we numerically calculated the magnetic field in all the pancake coil, taking into account the hysteretic nature of the supercurrents. The agreement of the calculated and measured profiles of radial component proves that the calculation method is correct. The radial component at room temperature, when the YBCO is not superconducting, is not hysteretic. In conclusion, the comparison of the experimental values of the radial field component at room temperature and 77 K provide information on the hysteretic currents in the superconductor. Moreover, our simulation method for the calculations is useful to predict the AC loss and the hysteretic effects of pancake coils.Index Terms-High temperature superconductors, loss measurement, magnetic field measurement, superconducting coils.

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Section: Introductionmentioning

confidence: 92%

Magnetic Field in the Winding of an YBCO Pancake Coil: Experiments and Calculations

Polák

Pardo

Mozola

et al. 2012

IEEE Trans. Appl. Supercond.

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“…For example, it has been reported that AC losses in CCs can be reduced by increasing the number of filaments [5][6][7][8]. This demonstrates the high applicability of CCs to electric power applications such as power transmission cables, transformers and superconducting magnetic energy storage.…”

Section: Introductionmentioning

confidence: 95%

Spatially-resolved measurement on time-dependent electromagnetic behavior in alternating current carrying coated conductor

Higashikawa

Honda

Inoue

et al. 2010

Physica C: Superconductivity and its Applications

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a b s t r a c tEstablishment of processing technology for multifilamentary coated conductors (CCs) is a key issue for superconducting electric power applications from the viewpoint of AC loss reduction. On the other hand, CCs sometimes have local inhomogeneity in the superconducting layers, and that will cause a current blocking in a filament or inhomogeneity of critical current among filaments in a multifilamentary CC. Therefore, we need an assessment method for local electromagnetic behavior on AC loss properties of CCs. In this study, we developed a method for visualizing time-dependent AC loss distribution in CCs by using scanning Hall probe microscopy. We succeeded in visualizing local current density, electric field and loss density simultaneously with a spatial resolution of a few hundred micrometers. The measurement system has possible scanning area of 150 Â 50 mm 2 and current capacity of 500 A. This enables us to discuss the local electromagnetic behavior on a practical scale of CCs. We believe that this visualization method will be a very powerful tool to estimate the feasibility of processing technology for multifilamentary CCs.

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“…The flow of evaporated nitrogen is translated into dissipated power by using a previously measured calibration curve. This approach is known as the boiloff method and has been applied to measure the AC losses in superconducting samples [20]; cables [21][22][23] and HTS coils under different operating conditions [19,[24][25][26][27][28]. In this work, a box-inside-a-box approach is used to surround the measurement chamber with a cryogenic environment.…”

Section: Introductionmentioning

confidence: 99%

Design and test of a setup for calorimetric measurements of AC transport losses in HTS racetrack coils

Vargas-Llanos

Krämer²,

Noë³

et al. 2023

Supercond. Sci. Technol.

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The estimation and measurement of AC losses in coils based on high-temperature superconductors (HTS) are relevant aspects of HTS applications. They influence the cooling power requirement, operating temperature and efficiency, which can be decisive in the construction and implementation of superconducting equipment, such as superconducting electrical machines. The measurement of losses due to AC transport current (without external magnetic field) is not an easy task. Several efforts have been made to measure these AC transport losses in superconducting coils with a calorimetric approach by trying to minimize the influence of the environment, improve the accuracy and ensure the reproducibility of the results. This work presents the design and construction of a setup to measure transport AC losses in high-temperature superconducting coils based on a calorimetric approach (boil-off method). The evaporated cryogen (nitrogen) related to the dissipation of energy is collected by using a 3D printed bubble collector that guides the gas into a flow sensor. A box-inside-a-box approach is used to surround the measurement chamber with a cryogenic environment. This approach allows re-directing the heat transfer from the surroundings into an intermediate zone (space between external and internal box). Since this intermediate zone operates under cryogenic temperatures, the noise and the heat transfer in the internal part of the setup are reduced. A statistical analysis of the results based on a standard load cycle, average value, and standard deviation calculations allows assessing the variability in the measurements and expressing the results as average value and uncertainty range. The calibration and reproducibility of the measurements are verified with a set of resistors under different conditions and during different weeks. Finally, the AC transport losses in a racetrack coil for an electrical machine application are measured and compared with 3D simulation results based on the homogenization of the T-A formulation.

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AC loss properties in YBCO model coils for loss reduction

Cited by 16 publications

References 1 publication

Magnetic Field in the Winding of an YBCO Pancake Coil: Experiments and Calculations

Magnetic Field in the Winding of an YBCO Pancake Coil: Experiments and Calculations

Spatially-resolved measurement on time-dependent electromagnetic behavior in alternating current carrying coated conductor

Design and test of a setup for calorimetric measurements of AC transport losses in HTS racetrack coils

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