• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.702_703
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• 2009

Electric Power Steering(EPS) system is superior to conventional Hydraulic Power Steering(HPS) system in aspect of fuel economy and environmental concerns. The EPS system consists of torque sensor, electric motor, ECU(Electric Control Unit), gears and etc. Among the elements, the torque sensor is one of the core technologies of which output signal is used for main input of EPS controller. Usually, the torque sensor has used torsion bar to transform torsion angle into torque. The torsion angle of both ends of a torsion bar is measured by a contact variable resistor. In this paper, the sensor is accurately analyzed using 3D finite element method and its characteristics with respect to four different shapes of the stator teeth are compared. The four shapes are rectangular, triangular, trapezoidal and circular type.

• Journal of Magnetics
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• 제17권4호
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• pp.285-290
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• 2012

Electric Power Steering (EPS) system is superior to conventional Hydraulic Power Steering (HPS) system in aspect of fuel economy and environmental concerns. The EPS system consists of torque sensor, electric motor, ECU (Electric Control Unit), gears and etc. Among the elements, the torque sensor is one of the core technologies of which output signal is used for main input of EPS controller. Usually, the torque sensor has used torsion bar to transform torsion angle into torque and needs linear characteristic in terms of flux variation with respect to rotation angle of permanent magnet. The torsion angle of both ends of a torsion bar is measured by a contact variable resistor. In this paper, the sensor is accurately analyzed using 3D finite element method and its characteristics with respect to four different shapes of the stator teeth are compared. The four shapes are rectangular, triangular, trapezoidal and circular type.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.104-106
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• 2003

In this paper, we study about the stator winding magnetization method and the magnetizing fixture magnetization method in post-assembly magnetization. Most of small electrical machine use the stator winding magnetization method but it is impossible to magnetize the permanent magnet by the stator winding magnetization method when the capacity of machine increases and the coercive force of magnet increases. And the eddy current disturbs the magnetization seriously in case of LSPM(Line Start Permanent magnet Motor) that have conductor bar in rotor. Hence, the magnetization fixture is required. So, in this paper we study about the post-assembly magnetization method that can use the stator winding magnetization method or must use the magnetization fixture magnetization method.

• 한국정보통신학회논문지
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• 제6권6호
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• pp.873-878
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• 2002

고정자 전류 스펙트럼(stator current spectrum)은 유도전동기의 고장 검출에 널리 사용되어왔다. 본 논문에서는 고정자 전류 스펙트럼 중에서 회전자 고장에 의해서 큰 영향을 받는 주파수 성분들로 특징벡터(feature vector)를 구성하고, 특징벡터와 기준벡터(reference vector)와의 평균 절대치 차이(mean absolute difference)를 구함으로써, 회전자 고장을 검출하는 방법을 제안한다. 제안한 방법에서는 전류 스펙트럼 중에서 추출된 매우 작은 크기(dimension)의 특징 벡터에 대한 평균 절대치 차이를 이용하기 때문에 신경회로망에 의한 고장 검출 알고리즘 둥에 비해서 훨씬 적은 계산량만으로 모터의 고장을 효율적으로 검출할 수 있다

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권12호
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• pp.797-806
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• 2000

In this paper, the torque characteristics and the bar loss distribution are analyzed when a general cage induction motor with skewed slots is fed by a 6-step inverter. For the electromagnetic analysis, time-stepping finite element method is used. And the multi-slice technique and sliding surface technique are respectively utilized to consider the skew effect and the rotation of the rotor. As a result, the effects of skewed rotor bar and the inverter output voltage on the characteristics of the torque and bar loss in the rotor are investigated. The simulation results are verified by measurement of flux density distribution axially in the stator teeth.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.475-480
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• 2006

In this paper, a new approach for detecting broken rotor bars in a squirrel-cage induction motor is proposed. The air-gap flux variation analysis was done using search coils inserted in stator slots when broken rotor bar occurs. An accurate modeling and analysis of air-gap flux variation in the induction motor are developed using finite-element (FE) software packages, and measurement of the flux are made using search coils. The simulation was done for the induction motor with 380 [V], 5 [HP], 4 Poles, 1,742 [rpm] ratings using the commercial FE analysis tool. The simulation and experiment results can be useful for detecting the broken rotor bar of an induction motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.975-976
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• 2007

Thermal and mechanical stresses, caused by repetitive start and stop and load fluctuation during long time operation, on winding stator bars are one of the main causes for electrical degradation of insulating materials. To understand the degradation process, we manufactured bar specimens with the same processes that make generator winding stator bars and the specimens were subjected to various degrees of thermal cycling. Measurements of the insulation properties, such as dissipation factor, tip-up and partial discharge, for un-aged specimens and for specimens aged by thermal cycling at 50, 100, 250, 500 and 1000 thermal cycles were performed. Finally all specimens were tested to obtain electrical breakdown voltages. In this paper we present the data and electrical degradation analysis results obtained during this program.

• 전기학회논문지P
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• 제56권1호
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• pp.51-55
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• 2007

In this paper, a portable rotor bar fault diagnosis system for small 3 phase induction motors is suggested. For portable real-tine diagnosis system, an USB-DAQ board for collecting the 3 phase current data, three current probes, and a notebook computer are used. The LabVIEW graphical language is used for filtering, analysis, storing, and monitoring the current data. The three phase stator current are filtered and transformed to frequency level by FIT. An analysis window programed by LabVIEW is located in front panel to show the FIT results and this suggested window has a zooming function to detect the fault feature more easily near the feature frequency range which is varying by the slip frequency. To show the possibility of portable rotor bar diagnosis system, three types(healthy, one rotor bar fault, two rotor bar fault) of rotor bar are intentionally prepared and compared by the suggested window of front panel. Experimental results are shown that a suggested diagnosis system is applicable to portable diagnosis system and the rotor bar fault is detected by the frequency window in front panel programed in LabVIEW graphical language.

• 조명전기설비학회논문지
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• 제28권7호
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• pp.41-47
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• 2014

The on-line partial discharge (PD) in stator windings of air-cooled gas turbine (GT) generator (119.2MVA, 13.8kV) is measured and analyzed in this paper. This generator was designed by global vacuum pressure impregnation (VPI). The generator failed two times at top bar (16T) of phase B in the stator slot. Six epoxy-mica capacitors were installed in three phases of GT generator. On-line PD test was performed on GT generator using turbine generator analyzer (TGA). TGA showed that the normalized quantity number (NQN) and the PD magnitude($Q_m$) were high in phase B. Internal discharges were generated in phases A, B and C. The trend analysis of NQN and $Q_m$ value are obtained in order to monitor the insulation condition in GT generator stator windings. Phases A and C were in good condition. But phase B had deteriorated significantly

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.827-828
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• 2006

This paper proposes a new method for detecting broken rotor bars in a squirrel-cage induction motor. The air-gap flux variation analysis was done using search coils inserted in stator slots when broken rotor bar occurs. An accurate modeling and analysis of air-gap flux variation in the induction motor are developed using finite-element(FE) software packages, and measurement of the flux are made using search coils. The simulation was done for the induction motor with 380 [V]. 7.5 [kW], 4 Poles, 1,760 [rpm] ratings using the commercial FE analysis tool. The simulation and experiment results can be useful for detecting the broken rotor bar of an induction motor.