• 한국초전도ㆍ저온공학회논문지
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• 제7권4호
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• pp.10-13
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• 2005

Transport current and magnetic field which is generated by transport current make AC current - AC mag-netic field condition(AC-AC condition) in AC power application system using HTS tape. Therefore, characteristics of AC loss under the AC-AC condition are necessary to estimate AC loss of power device with accuracy such as HTS transformer. In this paper, we researched transport current loss, magnetization loss by perpendicular magnetic field and total loss which is represented as summation of both losses under the AC-AC condition in single HTS tape. As a result, magnetization loss showed increasing behavior under 65mT and decreasing behavior upper 65mT by influence of transport current. Transport current loss was increased continuously through out whole measurement ranges in the AC-AC condition. Total loss in HTS tape was dominated entirely by magnetization loss.

• Journal of Magnetics
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• 제16권4호
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• pp.417-422
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• 2011

This paper presents the characteristics of PM eddy current loss and harmonic iron loss for PM step-skewed Interior Permanent Magnet Synchronous Motor (IPMSM) with concentrated windings and multi-layered PM under the running condition of maximum torque per ampere (MTPA) and flux-weakening control. In particular, PM eddy current loss and harmonic iron loss in IPMSM have been numerically computed with three-dimensional Finite Element Analysis (3D FEA), whereby IPMSM with concentrated windings and multi-layered PM has been designed to identify the optimized skew angle contributing to the reduced PM eddy current loss and torque ripples, while maintaining the required average torque. Furthermore, numerical investigation on PM eddy current loss and iron loss at MTPA and flux-weakening control has been carried-out in terms of PM step-skew.

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.55-60
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• 2002

$100 A/mm^2$ class Bi-2223 tapes have recently become commercially available. Some important characteristics of the tapes, e .g. critical current, ac loss, characteristics at joint, fault current characteristics, are required for an application such as a power cable or a power transformer. In this paper they have been investigated experimentally. The results indicate that the self-field loss of the high current density tapes is not negligible, compared to resistive loss in a copper wire for the same currents. In a cable, the self-field loss for relatively large currents is much larger than the magnetization loss due to an external field. But in a transformer, the magnetization loss is dominant, compared to the self-field loss. Finally the fault current characteristics show that the high current density tapes are never safe from burn-out even for fault currents with a few cycles.

• 한국전기전자재료학회논문지
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• 제16권5호
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• pp.418-423
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• 2003

AC loss is an important issue in the design of high-T$\sub$c/ superconducting power cables which consist of a number of Bi-2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. These make loss measurements considerably complex, especially for short samples of laboratory size. So special cautions are required in the positioning of voltage leads for measuring the true loss voltage. In this work we have prepared a conductor composed of three Bi-2223 tapes with different critical currents. The critical current and AC loss characteristics in the conductor have experimentally investigated. The results show that for uniform current distributions the conductor's critical current is proportional to the critical current of the Bi-2223 tape to which a voltage lead is attached. However it depends on the current non-uniformity parameter in the conductor rather than the tape's critical currents for nonuniform current distributions. The loss tests indicate that the AC loss is dependent on arrangements of voltage leads but not on their contact positions. The measured losses in the conductor also agree well with the sum of the transport losses measured in each Bi-2223 tape.

• 한국전기전자재료학회논문지
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• 제18권4호
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• pp.370-374
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• 2005

AC loss of a superconducting conductor has a strong influence on the economic viability of a superconducting fault current limiter, which offers an attractive means to limit short circuit current in power systems. Therefore, the AC loss characteristics in several fault current limiting elements of a coil type have been investigated experimentally. The test result shows that AC losses measured in the fault current limiting elements depend on arrangement of a voltage lead. The AC loss of a bifilar coil is smallest among the fault current limiting elements of the coil type. The measured AC loss of the bifilar coil is much smaller than that calculated from Norris's elliptical model. However, the loss measured in a meander, which is frequently used in a resistive fault current limiter, agrees well to the theoretical one.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.129-138
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• 2011

Performance changes of an anode-supported tubular SOFC including current collectors are analyzed at different current collecting methods using numerical simulation. From the two dimensional numerical model of the solid oxide fuel cell with nickel felts as anodic current collectors and silver wires as cathodic ones, the performance curves and the distributions of temperature, concentration, current density are obtained. Also, the voltage loss of the cell is divided into three parts: activation loss, concentration loss and ohmic loss. The results show that the performance change of the cell is dominantly influenced by the ohmic loss. Although the temperature and concentration distributions are different, the total activation loss and concentration loss are nearly same. And the ohmic loss is divided into each parts of the cell components. The ohmic loss of the anodic current collectorreaches about 60~80% of the cell's total ohmic loss. Therefore, the reduction of the ohmic loss of the anodic current collector is very important for stack power enhancement. It is also recommended that the load should be connected to the both ends of the anodic current collector.

• 자원리싸이클링
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• 제11권5호
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• pp.34-38
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• 2002

최근 전자기기의 경박단소화로 페라이트 코아의 사용주파수가 고주파화 되고 있다. Mn-Zn ferrites에서 전력손실은 hysteresis loss, eddy current loss, residual loss로 구성되어 있으며, 500 KHz 이상의 주파수 영역에서는 residual loss가 주도적인 손실을 나타낸다. Induction level이 50 mT 이하인 경우 전력손실은 주파수의 3승 이상에 비례하여 증가한다. 작은 grain과 치밀한 미세구조는 고주파 대역에서 eddy current loss를 감소시킬 뿐만 아니라 자속밀도를 증가시켜 Residual loss역시 억제한다. Resonance frequency와 static permeability를 곱한 값이 큰 시편일수록 고주파 영역에서 낮은 전력손실을 보인다.

• 전기학회논문지
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• 제66권6호
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• pp.911-915
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• 2017

Recently, there has been an increasing interest in the non-contact power transmission method of magnetic gears. Since there is no mechanical contact, noise caused by friction can be reduced, and even if a sudden large force is applied, the impact of the gear is close to zero. Further, since the power is transmitted by the magnetic flux, it has high reliability. However, there is a problem that a loss due to a magnetic field due to use of a magnetic flux. The loss caused by the magnetic field of the magnetic gear is a joule loss called eddy current loss. In addition, the eddy current loss in the magnetic gear largely occurs in the permanent magnet, but it is a fatal loss to the permanent magnet which is vulnerable to heat. Particularly, magnetic gears requiring high torque density use NdFeB series permanent magnets, and this permanent magnets have a characteristic in which the magnetic force decreases as temperature increases. Therefore, in this paper, the eddy current loss of the permanent magnet according to the permanent magnet attaching method is analyzed in order to reduce the eddy current loss of the permanent magnet. We have proposed a structure that can reduce the eddy current loss through the analysis and show the effect of reducing the loss of the proposed structure.

• 한국초전도ㆍ저온공학회논문지
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• 제7권3호
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• pp.17-20
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• 2005

AC loss of a high $T_c$ superconducting conductor has a strong influence on the economic viability of a superconducting fault current limiter, which offers an attractive means to limit short circuit current in the power systems. Therefore, several samples of the fault current limiting coils have been fabricated and the effect of conductor's arrangement and current direction on AC loss characteristics investigated experimentally The test result shows that the AC losses measured in the fault current limiting coils depend significantly on the conductor's arrangement. Futhermore, they are also considerably influenced by the conductor's current direction. The AC loss measured in the face-to-face arrangement is smallest among the fault current limiting coil samples.

• 한국초전도ㆍ저온공학회논문지
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• 제13권2호
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• pp.13-16
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• 2011

This paper describes the reduction method of eddy current loss generated into a retaining ring installed in wound-field superconducting machine. In order to suggest the reduction method of eddy current loss of the retaining ring, this paper is divided into three parts. Firstly, eddy current loss of prototype model is calculated. Secondly, eddy current loss versus material and shape of the retaining ring is compared. Finally, the material and the shape of the retaining ring to reduce coupling loss generated by a time-varying magnetic field are proposed. In this paper, eddy current loss is calculated by 3-dimensional transient analysis.