• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권3호
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• pp.110-116
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• 1999

This paper describes the effect of eddy currents in the rotor steel shell of exterior-rotor permanent magnet BLDC motor of which rotor is revolving at a high speed. A two-dimensional time-stepping finite element method is used for analyzing electromagnetic field and computing performances of the motor. As a result the effect of the eddy currents in the rotor steel shell is shown by comparing the analysis results from both the proposed method and the conventional one.

• 대한전기학회논문지
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• 제41권1호
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• pp.18-23
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• 1992

Magnet core and rail of a magnetically levitated vehicle are usually made of highly conductive materials. Accordingly, eddy currents are induced in those members. Eddy currents often lead to a decrement of levitation and guidance force. This paper has calculated the decrement of both forces due to eddy current generated by magnet's vertical and lateral motion. U-shaped electromagnet and rail were chosen as amodel of 2D finite element analysis. Calculated results proved that both forces dropped significantly at high speed. Consequently, effects of eddy current should be considered in designing the magnet and control system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.118.4-118
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• 2002

$\textbullet$ Magnetic floor hinge $\textbullet$ Recovering torque $\textbullet$ Eddy Currents $\textbullet$ Magnetic damper $\textbullet$ Optimal design $\textbullet$ Cost optimization

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.551-552
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• 2011

In this study new evaluation method of eddy currents in conductive shielding sheets are introduced. This method is based on the magnetic flux linkage in rectangular cells. According to this method the allocated amount of memory and the calculation time can be reduced. In this method calculation of magnetic field in any space can be performed by summing contributions of source currents and eddy currents in conductive shielding sheets. This method is applicable to the design of magnetic field-shield.

• Investigative Magnetic Resonance Imaging
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• 제18권3호
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• pp.244-252
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• 2014

목적 : 멀티 생체신호를 이용한 지능형 실시간 심장과 호흡에 동기화 하는 시스템을 사용하여 심장자기공명영상을 수행하였다. 또한 멀티 생체신호를 측정하는 과정에서 유기될 수 있는 eddy current의 특성을 분석하였다. 대상 및 방법 : 멀티 생체신호 동기화 시스템에서는 심전도 신호와 호흡신호 외에 추가로 $SPO_2$ 정보를 수집하여 심장의 움직임에 동기화 하였다. 심장운동의 동기화는 심전도와 함께 $SPO_2$의 이차미분 신호를 이용할 수 있음을 보였다. 심장 동기화 과정에서 피검자의 움직임과 부정맥에 의해 발생할 수 있는 잘못된 동기신호를 평균 R-R 시간을 이용하여 제거하였다. 심장 영상화를 위한 시퀀스에서 경사자계의 스위칭에 의해 유기될 수 있는 eddy current의 특성을 분석하여 하드웨어 및 소프트웨어 필터로 차단하였다. 결과 : 제안된 동기화 시스템을 이용하여 심장과 호흡 운동에 동기화된 심장자기공명영상을 얻었다. 심전도 신호에서 피검자의 움직임과 부정맥에 의해 발생할 수 있는 동기신호를 차단하였고, 심장 영상화 과정에서 유기될 수 있는 eddy current를 제거하였다. 또한 심전도 신호를 보완하여 $SPO_2$의 이차미분신호를 이용하여 심장 영상이 가능함을 보였다. 결론 : 본 논문에서 제안한 멀티 생체신호 동기화 시스템은 심장자기공명영상을 위해 여러 생체신호 (심전도, $SPO_2$, 호흡)를 이용하여 실시간으로 심장과 호흡 동기화를 수행한다. 심전도에서 피검사자의 움직임과 부정맥에 의해 발생할 수 있는 동기 신호를 차단하였다. 경사자계의 스위칭에 의해 생체신호에 유기될 수 있는 eddy current를 분석하였고, 심장과 호흡 동기를 병행하여 피검사자가 자유롭게 호흡하면서 심장 영상을 얻을 수 있었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.258-261
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• 1998

Induction heating is commonly used in process heating prior to metal working and in heat treationg, welding, and melting. For an analysis of induction heating system, it is necessary to calculate eddy currents in conductors induced by a source current. This study examines the use of the Impedance Boundary Condition for the reduction of the field problem encountered in the computation of eddy currents in non-magnetic and magnetic conductors with small penetration depths to a simpler exterior problem. The electric field intensities on the conductor surfaces computed by using the IBC are compared with the values obtained from the full region solution (i.e. without the use of IBC) and those agree well with the latter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.651-652
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• 2006

This research presents a topology optimization for manipulating the main heat flow in coupled magneto-thermal systems. The heat generated by eddy currents is considered in the design domain assuming an adiabatic boundary. For a practical optimization, the convection condition is considered in the topological process of the thermal field. Topology design sensitivity is derived by employing the discrete system equations combined with the adjoint variable method. As numerical examples, a simple iron and a C-core design heated-up by eddy currents demonstrate the strength of the proposed approach to solve the coupled problem.

• Journal of Power Electronics
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• 제18권5호
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• pp.1577-1584
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• 2018

The content of harmonic current increases with an increase in the number of power electronic devices in power grid. When a generator is directly connected to the power grid through a step-up transformer, the influence of the harmonic currents on the generator is inevitable. To study the influences of harmonics on generators, a 24-MW bulb tubular turbine generator is taken as an example in this paper. A 2-D transient electromagnetic field model is established. Through a comparative analysis of the data of experiments and simulations, the correctness of the model is verified. The values of the air gap magnetic density, torque and losses of the generator under various conditions are calculated using the finite element method. Taking the rated condition as a reference, the influence of the harmonic currents on the magnetic flux density is analyzed. It is confirmed that the time harmonic is a key factor affecting the generator performance. At the same time, the effects of harmonic currents on the torque ripple, average torque and eddy current loss of the generator are studied, and the mechanism of the variation of the eddy current loss is also discussed.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권10호
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• pp.483-493
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• 2001

The 3-phase induction is used for the MCP(main coolant pump) and the pure water is used for lubrication of bearing because of the difficulty of repair. Therefore the type of motor is the canned-motor that is welded by sealed can to prevent the stator and rotor from the lubricating water. A lot of Eddy currents are produced in the can because of the conductivity of material. And these eddy currents in the can are the most important cause that decrease the efficiency of induction motor. Therefore we have to find the method to decrease these eddy currents in the can for the improvement of efficiency of motor. In this paper, we proposed the method of design and analysis of canned-motor using equivalent circuit with consideration of can loss for the improvement of efficiency of motor.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1336-1343
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• 2005

The detection mechanism of the flaw for the nondestructive testing using eddy current is related to the interaction of the induced eddy currents in the test specimen with flaws and the coupling of these interaction effects with the moving test probe. In this study, the two-dimensional electromagnetic finite element analysis(FEM) fur the eddy current signals of the aluminum plate with different depth of surface cracks is described and the comparison is also made between experimental and predicted signals analyzed by FEM. In addition, the characteristics of attenuation of the eddy current density due to the variation of the depth of a conductor are evaluated. The effective parameters for the application of eddy current technique to evaluate surface cracks are discussed by analyzing the characteristics of the eddy current signals due to the variation of crack depths.