Numerical evaluation of AC losses in HTS wires with 2D FEM formulated by self magnetic field

Komori, Kazuhiro; Hayashi, Toshihiro; Yoshida, Ryuji; Iwakuma, Masataka; Funaki, K.

doi:10.1109/tasc.2003.812415

Cited by 78 publications

(69 citation statements)

References 14 publications

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“…14,15) The width 2a and thickness 2b in the x-and y-directions of the superconducting tape with an infinite length in the z-direction are assumed to be 10 mm and 0.1 mm, respectively, and therefore, the aspect ratio of the cross section is 100. This assumption helps in carrying out efficient numerical analysis even with a limited number of computer resources and validating the proposed method.…”

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confidence: 99%

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

Komori¹,

Funaki²

2011

Supercond. Sci. Technol.

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Application of an external AC magnetic field parallel to superconducting tapes helps in eliminating the magnetization caused by the shielding current induced in the flat faces of the tapes. This method helps in realizing a magnet system with high-temperature superconducting tapes for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) applications. The effectiveness of the proposed method is validated by numerical calculations carried out using the finite-element method and experiments performed using a commercially available superconducting tape. The field uniformity expected for practical applications is estimated to be less than 1 ppm.Superconducting magnets used in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) require a highly uniform magnetic field at their center.Hence, a multifilamentary superconducting wire with a circular or rectangular cross section composed of low-temperature superconductors such as NbTi or Nb 3 Sn is wound around the magnets. These materials are usually cooled by liquid helium, which has a boiling temperature of 4.2 K at atmospheric pressure. However, because of the rapidly increasing demand for liquid helium and its limited availability, the cost of this coolant has been increasing steadily. To realize a helium-free superconducting magnet system, 1)it would be necessary to use liquid hydrogen or nitrogen, whose boiling temperatures are about 20 K and 77 K, respectively, as a coolant, or carry out conduction cooling with the help of a cryocooler. Recently, a superconducting magnet with a nominal field of 0.5 T has been wound with a MgB 2 wire and installed in a private clinic for use in MRI. 2)Nevertheless, designing a very high normal field (several tesla or several tens of tesla) magnet using the MgB 2 wire for MRI and NMR applications is very difficult because the critical current density decreases drastically when the magnetic field is on the order of a few tesla.3) High-temperature superconductor (HTS) wires such as first-generation *

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confidence: 99%

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

Komori¹,

Funaki²

2011

Supercond. Sci. Technol.

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“…We use the critical state model (CSM) or n-value model (NVM) for the electric field vs. current density property in the SC strip. The resistivity ρ as a function of the local current density J φ = ∂T r /∂z for the CSM and NVM can be expressed by [13] …”

Section: Modeling and Calculation Methodsmentioning

confidence: 99%

Numerical reproduction of screening-current-induced fields in HTS tape windings using finite element method

Okabe

Honda

Komori

2017

J. Phys.: Conf. Ser.

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Abstract. The screening-current-induced fields in one of the high temperature superconducting (HTS) coils fabricated previously with coated conductors are evaluated numerically by using a one-dimensional finite element method, in which only the perpendicular component of a current vector potential is considered due to a very thin superconductor layer in the coated conductor. It is assumed that the voltagecurrent characteristics in the superconductor layer can be expressed by the critical state or n-value model, in which the field-dependent critical current density is also taken into account. The numerically calculated results of the screening-current-induced fields are compared with the experimental results carried out previously.

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“…2, where only a half part is taken into account because of its symmetric configuration. In this case, the governing equation formulated with a magnetic field H due to a current induced in the analysis region excluding the iron core is expressed by [23] …”

Section: Ac Loss Evaluation Of Stator Windingmentioning

confidence: 99%

“…Equation (5) is discretized with the Galerkin and backward difference methods for two-dimensional space and time, respectively, and the derived simultaneous equations are solved iteratively at each time step [23], [24]. By using the obtained distribution of magnetic field, the AC loss power P per unit length is numerically estimated with [23] …”

Section: Ac Loss Evaluation Of Stator Windingmentioning

confidence: 99%

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Proposal of a Fully Superconducting Motor for Liquid Hydrogen Pump With MgB<formula formulatype="inline"><tex Notation="TeX">$_{2}$</tex> </formula> Wire

Komori

Nakamura

2009

IEEE Trans. Appl. Supercond.

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Abstract-The outline design of a fully superconducting motor for liquid hydrogen pump with a magnesium-diboride (MgB2) superconducting wire is carried out to present various advantages arising from its prospective performances. The squirrel-cage rotor winding composed of superconducting loops with the MgB2 wire enables us to operate the motor not only in a slip mode but also in a synchronous rotation mode, and consequently the rotor winding loss can be suppressed drastically. Furthermore, it would be expected that the stator winding loss becomes smaller by using the MgB2 wire compared with familiar normal metals as typified by a copper. The time evolution of magnetic field distribution around the stator winding is obtained by means of a finite element analysis in order to estimate the AC loss and the primary circuit resistance.

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Numerical evaluation of AC losses in HTS wires with 2D FEM formulated by self magnetic field

Cited by 78 publications

References 14 publications

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

Numerical reproduction of screening-current-induced fields in HTS tape windings using finite element method

Proposal of a Fully Superconducting Motor for Liquid Hydrogen Pump With MgB<formula formulatype="inline"><tex Notation="TeX">$_{2}$</tex> </formula> Wire

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