Flux Deflection on Rotating Field Pole Magnets for HTS Machines

Tsuzuki, K.; Miki, M.; Felder, B.; Watasaki, Masahiro; Kase, Shintaro; Sato, Ryo; Izumi, Mitsuru

doi:10.1109/tasc.2013.2238973

Cited by 12 publications

(5 citation statements)

References 16 publications

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“…Ferromagnets can also increase the force in levitation systems [16,17] and close the magnetic circuit, which improves the available flux produced by bulk superconductors [18]. Similarly, ferromagnetic materials are used as sheaths around multifilament wires and tapes [19,20] or as magnetic flux diverters to modify the flux distribution around tapes and superconducting coil magnets [21][22][23][24][25][26][27][28]; thereby improving their electrical properties (i.e. increasing the critical current and reducing ac losses).…”

Section: Introductionmentioning

confidence: 99%

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Philippe

Ainslie

Wera

et al. 2015

Supercond. Sci. Technol.

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Bulk, high temperature superconductors have significant potential for use as powerful permanent magnets in a variety of practical applications due to their ability to trap record magnetic fields. In this paper, soft ferromagnetic sections are combined with a bulk, large grain Y-Ba-Cu-O (YBCO) high temperature superconductor to form superconductor/ferromagnet (SC/FM) hybrid structures. We study how the ferromagnetic sections influence the shape of the profile of the trapped magnetic induction at the surface of each structure and report the surface magnetic flux density measured by Hall probe mapping. These configurations have been modelled using a 2D axisymmetric finite element method based on the H-formulation and the results show excellent qualitative and quantitative agreement with the experimental measurements. The model has also been used to study the magnetic flux distribution and predict the behaviour for other constitutive laws and geometries. The results show that the ferromagnetic material acts as a magnetic shield, but the flux density and its gradient are enhanced on the face opposite to the ferromagnet. The thickness and saturation magnetization of the ferromagnetic material are important and a characteristic ferromagnet thickness d* is derived: below d*, saturation of the ferromagnet occurs, and above d*, a weak thicknessdependence is observed. The influence of the ferromagnet is observed even if its saturation magnetization is lower than the trapped flux density of the superconductor. Conversely, thin ferromagnetic discs can be driven to full saturation even though the outer magnetic field is much smaller than their saturation magnetization. [5,6]) is well beyond the saturation magnetization of conventional ferromagnets. This makes them extremely promising as a competing technology for traditional permanent magnets in various applications [7][8][9][10]. The combination of ferromagnetic and superconducting materials can enhance the performance of the superconductor [11,12] and even lead to new applications [13]. Large grain, bulk superconductors are often used in applications that incorporate ferromagnetic materials, such as in motors and generators [14,15]. Ferromagnets can also increase the force in levitation systems [16,17] and close the magnetic circuit, which improves the available flux produced by bulk superconductors [18]. Similarly, ferromagnetic materials are used as sheaths around multifilament wires and tapes [19,20] or as magnetic flux diverters to modify the flux distribution around tapes and superconducting coil magnets [21][22][23][24][25][26][27][28]; thereby improving their electrical properties (i.e. increasing the critical current and reducing AC losses).

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Section: Introductionmentioning

confidence: 99%

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Philippe

Ainslie

Wera

et al. 2015

Supercond. Sci. Technol.

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“…Experiments to evaluate the effect of flux deflection technique with prototype HTS field pole for application in a large scale rotating machine has been conducted. The results obtained from the evaluation showed significant effect to reduce heat generation in operating temperature such as both of 30 K and 77 K [12].…”

Section: Introductionmentioning

confidence: 94%

Improvement of Flux Deflection With Light-Weight Magnetic Material

Tsuzuki

Kase

Miki

et al. 2015

IEEE Trans. Appl. Supercond.

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Intensified magnetic flux generated by hightemperature superconducting (HTS) field-pole magnet has been studied for the key to improve the machine efficiency of industrial application. An increase of the critical current density allows a further improvement of the operating current in HTS ship propulsion motors. In our previous work, an effect of flux deflection to the critical current of HTS magnet was evaluated. Magnetic flux deflection is a technique to control perpendicular flux to the a-b plane of the HTS tape by magnetic material. Thanks to the magnetic properties of the material, heat loss reduction was confirmed. In this paper, the outcome of the verification experiment with a lightweight magnetic material FINEMET adopted as magnetic flux deflector will be described. In response to the results which increase of the total weight of HTS winding by mounting a magnetic material, weight reduction of the magnetic flux deflector is necessary for practical employment. Compared with the carbon steel, FINEMET has higher saturation magnetic flux density and higher permeability. I-V curve was measured while a pair of the magnetic flux deflectors were installed on the prototype HTS coil connected to the DC current source. In the case of adopting light-weight magnetic material, the reduction of heat generation was confirmed to be 27% which is equivalent to the previous material. At the same time, a weight reduction of 73% was achieved. Results show that FINEMET is effective to improve flux deflection. It is one of feasible material which can be adapted to the field-pole magnet of practical HTS propulsion motor.Index Terms-Bi2223 tape amorphous magnetic alloy, heat generation, HTS rotating machine, HTS winding, magnetic vector.

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“…We have developed 3 MW HTS motor for ship propulsion [14][15][16][17][18][19][20][21][22][23][24]. The quench protection circuit was tested using one field pole of a rotor as shown in figure 3.…”

Section: Test Of a Quench Protection Circuit 31 Field Pole Of A 3 Mw ...mentioning

confidence: 99%

“…The electromagnetic energy stored in the HTS coils is absorbed in the dispersed parts and the dump resistors can be made smaller and easier to install on a HTS ship propulsion motor. We have fabricated a quench protection circuit for the HTS field pole of a 3 MW HTS motor developed by Kawasaki Heavy Industries [14][15][16][17][18][19][20][21][22][23][24]. The fabricated quench protection circuit was tested successfully and demonstrated to be effective in quench protection.…”

Section: Introductionmentioning

confidence: 99%

Design and test results of a novel quench protection circuit for a HTS ship propulsion motor

Murase¹,

Izumi²,

Umemoto³

et al. 2021

Eng. Res. Express

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This paper describes a novel configuration of a quench protection circuit for a high-temperature superconducting (HTS) ship propulsion motor that can protect the HTS coils from an unexpected outage in its cryogenic cooling system. The quench protection circuit consists of conductor parts placed adjacent to the HTS coils and dump resistors and diodes placed in the cryogenic-temperature and normal-temperature areas, respectively. The conductor parts are shaped and arranged such that the magnetic coupling with the HTS coil is extremely large. Thereby, the current of the HTS coils can be instantaneously attenuated immediately after the quench protection is activated. With this configuration, the electromagnetic energy of the HTS coils can be absorbed in the dispersed parts. This can make the dump resistors smaller and make it easier to install them on a HTS ship propulsion motor. By analysing the equivalent electric circuit model of the protection circuit, we derived the conditions under which instantaneous current attenuation of the HTS coil occurs. In accordance with the conditions, we have fabricated a quench protection circuit that protects one HTS field pole of the 3 MW HTS motor developed by Kawasaki Heavy Industries. The fabricated circuit was empirically evaluated and proved to be highly effective in quench protection. The present quench protection circuit technology contributes to the practical application of HTS ship propulsion motors.

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Flux Deflection on Rotating Field Pole Magnets for HTS Machines

Cited by 12 publications

References 16 publications

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Improvement of Flux Deflection With Light-Weight Magnetic Material

Design and test results of a novel quench protection circuit for a HTS ship propulsion motor

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