• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.834-836
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• 2001

This paper deals with analysis for demagnetization characteristic of a ferrite magnet line start motor using FEM. Maximum start and clock currents are calculated by transient state voltage and dynamic equation, and then, these currents are applied to FE analysis. The characteristics of motor according to partial demagnetization are analyzed from FE analytic results, and rotor shape is designed for improvement of demagnetization characteristic.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권2호
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• pp.129-136
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• 2005

This paper presents a design strategy of SPOKE type BLDC motors considering an irreversible demagnetization of a permanent magnet (PM). So the irreversible demagnetization characteristic of the motor is analyzed by rotor structure. The instantaneous currents in either starting or lock rotor condition, which are calculated from the current dynamic analysis, are applied to the analysis of the irreversible demagnetization field by FEM. In irreversible demagnetization analysis by FEM, the variation of residual flux density in PM is analyzed using the non-linearity of magnetic core on B-H plan. The analysis results are compared to several rotor structures and used for optimize the rotor structure.

• 전기학회논문지
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• 제60권8호
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• pp.1502-1509
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• 2011

This Paper presents characteristic analysis in terms of interior permanent magnet synchronous motor for electric vehicle propulsion using numerical analysis. Torque ripple analysis, thermal analysis, demagnetization analysis of permanent magnet and mechanical stress analysis with variable operating condition are presented. According to these characteristic analysis, both the performance of motor and possible problems during the operation are examined thoroughly in advance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.113-115
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• 2008

At the high speed operation, the high demagnetization voltage can reduce the negative torque, so the output power and efficiency can be improved. In this paper, a novel power converter for single phase SRM with high demagnetization voltage is proposed. A simple passive capacitor circuit is added in the front-end, which consists of three diodes and one capacitor. Based on this passive network, the two capacitors can be connected in series and parallel, so the phase winding of SRM obtains general do-link voltage in excitation mode and the double dc-link voltage in demagnetization mode. The operation modes of the proposed converter are analyzed in detail. Some computer simulation results is done to verify the performance of proposed converter.

• 조명전기설비학회논문지
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• 제20권1호
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• pp.100-110
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• 2006

자속 역전식 전동기(Flux Reversal Motor: FRM)는 고정자 치 표면에 영구자석을 갖는 구조이며 회전자가 돌극 형태이므로 관성이 적고 기계적으로 강인한 특성을 지녀서 고속기로의 적용이 가능하다. 그러나 단상 FRM은 구조적 특징으로 인하여 영구자석의 감자가 쉽게 일어나며, 고속 구동시 스위칭 주파수가 커짐에 따라 철손이 크게 상승하게 된다는 한계점을 지닌다. 본 논문에서는 유한요소법을 이용하여 단상 FRM의 설계 파라미터가 전동기의 감자특성에 주는 영향을 고찰해보았고 그 해결 방안을 제시하였으며 철손 특성을 분석하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.863_864
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• 2009

Design and drive characteristics of SR drive for hydraulic pump system using passive converter is presented in this paper. In oder to get the high performance, a simple passive circuit is added in the front-end of a conventional asymmetric converter, which consists of three diodes and one capacitor. This passive converter has the high demagnetization voltage, to reduce the demagnetization time. Futhermore optimal turn-off angle for the proposed passive converter is proposed. According to motor speed and current, an optimal turn-off angle can be achieved by look-up table to reduce torque ripple. The characteristic of proposed hydraulic pump system using passive converter is verified by simulation and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.74-76
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• 2004

This paper deals with the analytical method to calculate the high temperature demagnetization characteristics of a high-speed machine with diametrically magnetized permanent magnet rotor. The equivalent magnetic circuit model is used to analyze the magnet operating point on high temperature condition. Agreements have been obtained between the results of the analytical model and finite-element analysis on prototype high-speed motors.

• 한국철도학회논문집
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• 제12권3호
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• pp.335-341
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• 2009

차세대 고속 전철용 매입형 영구자석 전동기의 효율 및 매입된 자석의 감자를 방지하기 위해서 정확한 철손해석과 철손특성을 이해하는 것은 전동기 설계단계에서 매우 중요하다. 본 논문에서는 견인전동기의 약계자 제어 및 최대토크 제어와 같은 구동상황을 고려하여 운전영역별 철손해석을 수행하고 특성을 분석하고자 한다.

• 자원환경지질
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• 제26권4호
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• pp.507-518
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• 1993

Paleomagnetic investigations have been carried out on the Tertiary sedimentary formations (Yeonil Group) in Pohang basin, southeastern Korea. A total of 215 samples were collected from 26 sites. Progressive thermal demagnetization indicates that many samples have unstable magnetization and do not reveal a characteristic direction. However, some samples from the lower and upper Duho Formation show a characteristic direction $D/I=7.8^{\circ}/48.3^{\circ}$ (${\alpha}_{95}=3.7^{\circ}$, k=174.1). Stepwise thermal demagnetization data show that some samples from the Hagjeon and middle Duho Formations reveal great-circle distributions moving from the present to a reversed direction of geomagnetic field. The mean of intersection points of the great-circles is nearly antipodal to the characteristic normal direction of the lower and upper Duho Formation. We infer that the Hagjeon Formation was formed during the reversed polarity chron C5B (16.2~14.7 Ma) and the Duho Formation 14.7~11.6 Ma based on our results and previous paleontologic and age dating data. Paleomagnetic direction for the Middle Miocene of Korea, analysed from the combined results of stable endpoints and great circles, is $D/I=8.7^{\circ}/53.9^{\circ}$ (${\alpha}_{95}=4.2^{\circ}$, k=74.8), and the corresponding paleopole is Lat./Long.=$82.7^{\circ}/230.2^{\circ}$ (${\delta}p=2.8^{\circ}$, ${\delta}m=5.9^{\circ}$). On the basis of this, we interpret that the opening of the East sea (Japan sea) or the synchronous clockwise rotation of the Southwest Japan exerted no structural influence on the Yeonil Group in the Middle Miocene.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.890-891
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• 2015

본 논문에서는 속도 제어를 위한 가변자속 메모리 모터(Variable Flux Memory Motor)의 특성과 감자전류 산정에 대하여 다루었다. 서론에서는 VFMM에 대한 특징 및 설계를 위한 분석 방안을 제시하였으며, 메모리모터의 동작 원리와, 정밀한 해석 방법은 본론을 통하여 자세히 다루었다. 감자전류는 프라이자흐 모델을 이용하여 초기 자석의 자화량을 비선형 적으로 구한 후 인가된 d축 전류에 따른 변화된 자화량 및 기전력 값들을 반복적인 연산을 통하여 신뢰성 있는 감자전류를 산정하였다.