• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.288-294
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• 2013

The diagnosis of motor failures using an on-line method has been the aim of many researchers and studies. Several spectral analysis techniques have been developed and are used to facilitate on-line diagnosis methods in industry. This paper discusses the first application of a motor flux spectral analysis to the identification of broken rotor bar (BRB) faults in induction motors using a multiple signal classification (MUSIC) technique as an on-line diagnosis method. The proposed method measures the leakage flux in the radial direction using a radial flux sensor which is designed as a search coil and is installed between stator slots. The MUSIC technique, which requires fewer number of data samples and has a higher detection accuracy than the traditional fast Fourier transform (FFT) method, then calculates the motor load condition and extracts any abnormal signals related to motor failures in order to identify BRB faults. Experimental results clearly demonstrate that the proposed method is a promising candidate for an on-line diagnosis method to detect motor failures.

• 정보저장시스템학회논문집
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• 제3권4호
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• pp.191-195
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• 2007

The optical disc drive has used a high NA objective lens and a shorter wavelength laser diode for high recording density. But high NA and shorter wavelength cause several margins to become short. Focusing and tracking servo has to be more accurate and active tilt compensation mechanism is also needed for coma aberration compensation. In this paper, we proposed 3-axis moving magnet type actuator. For 3-DOF motion, moving coil actuator has to be equipped with 6 wires for supplying 3 independent signals. However, moving magnet type actuator doesn't need to change the configuration of wires because coils are in stator. So, we added a tilt mechanism to the 2-axis moving magnet actuator which is designed in previous research. Addition of the tilt mechanism cuts down the focus sensitivity. So, maximization the tilting sensitivity and securing the focusing sensitivity are objectivities of this research. DOE (design of experiments) procedures of electromagnetic circuit are performed for parameter study and the optimization is also performed to maximize the tilt sensitivity. And then the final design is suggested and its performance is verified by FE simulation.

• 전력전자학회논문지
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• 제9권5호
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• pp.448-456
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• 2004

본 논문에서는 스위치드 릴럭턴스 모터의 새로운 회전자 위치 검출법을 제안한다. 기존의 위치센서의 약점을 보완하기 위해 위치 검출 방법의 저 비용과 강인성에 초점을 두고, 시변 쇄교자속에 의해 TSRM(Toroidal Switched Reluctance Motor) 돌극의 홈에 장착된 서치코일에 유기되는 전압 파형을 이용하여 위치 검출을 시도하였다. 회전자의 위치정보를 포함하고 있는 서치코일에서 유기되는 전압 파형을 이용해 회전자의 특정위치를 검출하고 적절한 상을 여자시킴으로써 SRM을 구동할 수 있게 된다. 실험을 통하여 서치코일만을 이용하여 토로이달 SRM을 구동시킨 결과와 엔코더를 사용하여 구동시킨 결과와 비교함으로써 본 논문에서 제시한 방법의 타당성을 검증하였다.

• Journal of Magnetics
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• 제20권1호
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• pp.79-85
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• 2015

This paper presents a comparative study of a Tubular Linear Machine (TLM) with an Axially Magnetized Single-sided Permanent Magnet (AMSPM) and an Axially Magnetized Double-sided Permanent Magnet (AMDPM) based on analytical field calculations. Using a two-dimensional (2-D) polar coordinate system and a magnetic vector potential, analytical solutions for the flux density produced by the stator windings are derived. This technique is significant for the design and control implementation of electromagnetic machines. The field solution is obtained by solving Maxwell's equations in the simplified boundary value problem consisting of the air gap and coil. These analytical solutions are then used to estimate the self and mutual inductances. Two different types of machine are used to verify the validity of these model simplifications, and the analytical results are compared to results obtained using the finite element method (FEM) and experimental measurement.

• 대한기계학회논문집A
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• 제37권7호
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• pp.899-903
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• 2013

셀프베어링 모터는 하나의 자기 구동기(magnetic actuator)로 회전 구동과 자기부상을 동시에 구현한 전동기로 베어링리스모터 혹은 베어링 내장 모터로 불리기도 한다. 셀프베어링 모터에서 자기부상제어를 구현하기 위해 부상력과 제어전류 간의 모델을 역변환하여야 하는데, 힘-전류 간의 모델을 결정하는 변환행렬이 정방행렬이 아니며, 의사역행렬(pseudo-inverse) 또한 회전자의 각도에 따라 특이점을 가지게 된다. 본 논문에서는 힘-전류 모델에 제한조건을 추가하여 연속적 역변환이 가능한 새로운 방법을 제시하고, 역변환 행렬을 해석적으로 구하였다. 연속적 역변환을 이용한 부상제어기를 구현하여 안정적 부상제어가 이루어짐을 확인하였다. 힘-전류 모델에 추가한 제한조건으로 상전류의 총합이 0 을 유지하여 전류에 의한 고정자 자속밀도를 제거함으로써, 이전 연구에서의 자기포화 문제를 근본적으로 해결하였다.

• 한국자기학회지
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• 제25권2호
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• pp.58-65
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• 2015

본 논문은 양측식 슬롯리스 고정자 할박 배열 영구자석 선형 발전기의 발전특성해석을 하였다. 자기 벡터자위와 맥스웰 방정식 이용하여 지배방정식을 도출하고, 특히 영구자석 자화와 고정자 권선의 전류밀도 분포는 무한 푸리에 급수을 이용하여 모델링 하였다. 도출된 지배방정식으로부터, 영구자석 및 고정자 권선에 의한 자계 특성식과 역기전력, 저항, 인덕턴스와 같은 회로정수를 도출 하였다. 발전 특성 해석 결과는 유한요소 해석법과 비교하여 매우 잘 부합함을 확인함으로 그 타당성이 검증되었다.

• 조명전기설비학회논문지
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• 제14권4호
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• pp.31-38
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• 2000

본 논문에서는 동기속도 이상의 풍속 영역에서 계풍연계된 DFTG(Doubly-Fed Induction Generaior) 시스템올 이용하여 발전기의 속도, 출력, 역률 제어에 대한 연구를 하였다. 이를 위하여 회전자 권선을 통하여 회전자 여자 주파수와 전압을 인가하였고,DBG의 전력소류와 등가회로의 정상상태 식을 해석하였다. 발전기의 속도와 고점차 일정출력제어는 회전자 여자주파수에 의해 이루어지고, 발전기의 정상적인 동작은 회전자 여자전류가 정격값올 넘어서는 안된다. 따라서 회전자 여자주파수에 의한 일정 출력운전상태에서 회전자 여자전류를 정격값이 되도록 회집자 여자전압을 제어여, 고정자 역률이 최적이 되도 DFIG를 운전하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.95-99
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• 2005

This paper presents a general proposal to design and calculate the performance of a tubular permanent magnet linear generator treated here on the basis of the Finite Element Method. Optimizing the linear generator dimensions reduces the cogging force, which occurs due to the interaction between stator teeth and the permanent magnets. The generated AC voltage is analyzed and evaluated for both no load and load cases to take the armature reaction effects on the air gap flux density. A repetitive routine is followed to calculate the output AC voltage from the change of flux and the speed of the single-phase linear generator. The AC output voltage is calculated for different resistive loads, and hence, the linear generator load characteristic is obtained. The designed linear generator is capable to generate an output power of 5.3kW with AC output voltage of 222V with an efficiency of 96.8% at full load of 23.8A. The full load current is chosen based on the thermal properties of the coil wire insulations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.187-190
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• 2002

In contrast to conventional electromagnetic motor, USM(Ultrasonic Motor), as piezoelectric ceramic applying ultrasonic mechanical vibration and as frictional-movement type motor, get rotational torque by elastic friction between stator and rotator, The USM, which is small motor without iron cores and coil as a simple structure, has little load weight, has character of high torque at low speed, and can apply a direct drive type without deceleration gear as low speed type. A response of USM from control input is satisfactory, and also generates much torque in low speed driving, and holding torque is much without supplying power. In this study, I designed and made Ultrasonic motor-digital multi controller(USM- DMC) using FPGA chip, A54SX72A made in Actel Corporation. By the minute, USM-DMC can control frequency, duty ratio, and phase difference of USM by llbit digital input from Pc. Therefore, when we use this controller, we can apply to typical parameter, frequency, phase difference, and voltage parameter, to control as well as we can do mixing control like phase-frequency, phase-voltage, frequency-voltage, frequency-phase-voltage, What is more, the strongest point is that it can trace frequency based on optimized frequency because we can input optimized resonant frequency while in motoring.