• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1139-1146
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• 2000

The frequencies of principal noise in interior permanent motor originate form two sources. One is torque ripple that is composed of cogging torque, magnetic torque ripple and reluctance torque ripple. The other is induced by natural frequencies. In this paper, the torque ripple and its influence on noise was examined by theoretical analysis. Understanding relation of dynamic characteristics and noise, natural frequencies and mode shapes were obtained by experimentation and operational deflection shape was observed. Finally, the method of predicting frequencies of principal noise was proposed.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2411-2418
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• 2017

This study focuses on the effects of using open stator slots in an interior permanent magnet traction motor with a magnetic slot wedge design in order to increase the power density at its base speed. In addition, such a configuration reduces the torque ripple under field-weakening conditions. Five different wedge models were selected, each of which was evaluated using a finite element analysis (FEA). Based on the initial model, we designed magnetic slot wedges for maximum back-EMF and minimum cogging torque. In addition, the d-q axis inductance was slightly altered due to the magnetic slot wedges. Finally, we analyzed the performance of a traction machine under field weakening control. Moreover, we have outlined the requirements for an ideal magnetic slot wedge design.

• 한국전자통신학회논문지
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• 제16권2호
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• pp.355-362
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• 2021

동축 마그네틱 기어는 비접촉 동력전달을 사용하기 때문에 기존 기계식 기어의 동력전달과정에서 발생하는 마찰, 마모, 소음, 발열을 최소화할 수 있다. 현재 다양한 산업에 적용하기 위한 연구가 활발히 진행되고 있으나 동축 마그네틱 기어가 갖는 특징 중, 높은 기어비에서 토크밀도가 급격히 감소하는 문제가 거론되었다. 본 논문은 높은 토크밀도를 갖는 저 기어비 동축 마그네틱 기어를 이용하여, 이들을 다중으로 결합하는 방향을 제시하였다. 해당 방법의 유효성을 확인하기 위해 단일형태의 고 기어비 모델과 토크밀도를 비교하고 다중 동축 마그네틱 기어의 기어비 조합을 분석함으로써 가장 우수한 조합을 선정하는 설계 방향을 나타내었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권6호
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• pp.728-732
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• 2014

Macro-model of magnetic tunnel junction (MTJ) for spin transfer torque magnetic random access memory (STT-MRAM) has been developed. The macro-model can describe the dynamic behavior such as the state change of MTJ as a function of the pulse width of driving current and voltage. The statistical behavior has been included in the model to represent the variation of the MTJ characteristic due to process variation. The macro-model has been developed in Verilog-A.

• 한국전자통신학회논문지
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• 제12권6호
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• pp.1065-1070
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• 2017

마그네틱 기어는 기계적인 접촉 없이 회전 기계의 입력측과 출력측이 자기적으로 결합되어 동력을 전달한다. 마그네틱 기어는 내측회전자, 외측회전자, 폴피스로 구성되어 있으며, 동력전달 시 두 회전체와 폴피스 사이의 자기저항 차이로 토크리플이 발생하게 된다. 이러한 토크리플은 회전기계의 소음과 진동의 원인이 되기 때문에 최소화하는 방안이 필요하다. 본 논문에서는 토크리플 저감 방안으로 폴피스의 각진 모서리를 깎아 필렛을 적용한 형상을 제안하였다. 2D 유한요소해석법을 활용하여 필렛 파라미터 변화에 따른 마그네틱 기어의 토크리플을 비교 및 분석하고 토크리플이 우수한 폴피스 형상을 모색하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.709-710
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• 2008

In this paper, we calculated permanent magnetic linkage flux ${\psi}_{\alpha}$ and Ld, Lq parameters of IPMSM and compared two model which has different barrier width. IPMSM has two kinds of torque that reluctance torque and magnetic torque. In constant torque region, using the Maxwell stress tensor method, we calculated the torque and current phase angle ${\beta}$ which has appeared maximum torque. In weakening flux region, we calculated the current phase angle ${\beta}$ which flux ${\psi}_o$ lower than limited flux ${\psi}_{omax}$. From the current phase angle ${\beta}$, we calculated torque by torque equation and compared two model characteristic.

• KEPCO Journal on Electric Power and Energy
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• 제5권3호
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• pp.229-233
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• 2019

Large-scale High Temperature Superconducting (HTS) wind power generators suffer from high electromagnetic force and high torque due to their high current density and low rotational speed. Therefore, the torque and Lorentz force of HTS wind power generators should be carefully investigated. In this paper, we proposed a Performance Evaluation System (PES) to physically test the structural stability of HTS coils with high torque before fabricating the generator. The PES is composed of the part of a pole-pair of the HTS generator for estimating the characteristic of the HTS coil. The 10 MW HTS generator and PES were analyzed using a 3D finite element method software. The performance of the HTS coil was evaluated by comparing the magnetic field distributions, the output power, and torque values of the 10 MW HTS generator and the PES. The magnetic flux densities, output power, and torque values of the HTS coils in the PES were the same as a pole-pair of the 10 MW HTS generator. Therefore, the PES-based evaluation method proposed in this paper can be used to estimate the critical characteristics of the HTS generator under high magnetic field and high torque before manufacturing the HTS wind turbines. These results will be used effectively to research and manufacture large-scale HTS wind turbine generators.

• 대한기계학회논문집A
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• 제21권1호
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• pp.53-61
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• 1997

The performance characteristics of magnetic fluid seals are studied numerically as a function of working gap, pole width, angle of pole sharpening, and shaft speed. The temperature distribution of a magnetic fluid seal with multiple tooth is investigated as a function of the contact fraction of magnetic fluids at the periphery of pole tooth using a finite element method. The most significant design parameter of a magnetic fluid seal is the working gap between the pole pieces and the rotating shaft. The result shows that with increasing the working gap, the friction torque decreases radically. The practical working gap for the pole pieces with triangular tooth zone profile is 0.2-0.4mm. The FEM results indicate that the optimal filling of a magnetic fluid between the pole pieces and the shaft is very important due to the accumulations of nonuniform friction heating within the pole pieces, which may interfere the magnetic circuit flow.

• 전기학회논문지
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• 제64권4호
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• pp.545-551
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• 2015

This paper deals with torque analysis of magnetic spur gear with radial magnetized permanent magnets based on analytical method. The analysis is implemented in three parts: First, on the basis of magnetic vector potential and a two-dimensional (2D) polar-coordinate system, the magnetic field solution due to permanent magnet of source gear are obtained. And by using derived magnetic field solutions, the analytical solutions for external magnetic field distribution which affects load gear are obtained. Second, by using coordinate conversion, external magnetic field which is on the primary coordinate system is converted to the secondary coordinate system. Finally, the load gear is reduced to equivalent current densities, and the torque is computed on these currents in the external field of the source magnet. These analytical results are validated by comparing with the 2-D finite element analysis (FEA).

• 한국전자통신학회논문지
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• 제15권2호
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• pp.259-266
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• 2020

자기 기어는 기계식 기어와 동일하게 기어의 특성을 나타내면서 각 회전자가 접촉하지 않아 마찰에 의한 소음 및 발열, 유지보수문제에서 기계식 기어보다 유리하다. 또한 권선계자를 사용하는 회전자를 적용할 경우 기어의 출력조절은 물론, 기어비 및 위급상황에서 자체적인 구동차단까지 가능하여 자기 기어의 활용가능성은 무한하다. 하지만 권선계자를 사용할 경우 영구자석과 철심간의 흡인력에 의한 코깅토크가 나타나게 되고 이는 회전자의 진동을 유발하는 토크 리플성분의 증가로 이어진다. 따라서 본 논문에서는 권선계자를 사용하는 회전자의 토크 리플을 저감하기 위해 회전자의 다양한 형상을 분석하였으며, 자기 기어의 토크 리플을 저감하기 위한 최적의 형상을 제시하였다.