• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1141-1145
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• 2014

3상유도전동기의 고정자 권선에 이상이 발생하면 직류 여자로 인한 권선 간 상호유도 응답에도 변화를 일으키므로 해당 특성을 전동기의 상태진단에 활용하는 것이 가능하다. 3상 평형 관계에 있는 고정자 권선 하나에 직류 전류를 흘릴 때 나머지 권선에서 유도되는 기전력은 항상 일치된 형태로 나타나며 이들 응답의 불일치 정도는 역으로 전동기의 이상 상태를 나타내는 척도가 된다. 과도 시 유도 기전력 간 불평형은 3상권선의 극성 결선에 오류가 있을 때 특히 크므로 기전력의 차동신호는 권선의 극성 판단 방법으로 활용하기에 적합하다. 본 연구에서는 직류 여자 신호와 이로 인한 나머지 권선에서의 유도전압 간 응답 관계를 전달함수로 나타내는 한편, 응답의 불일치 정도를 가리키는 차동 신호 전압을 멀티테스터로 측정하는 실험을 통해 권선 극성의 이상여부를 현장에서 용이하게 판단할 수 있는지를 확인하는 한편 교류여자의 경우도 함께 살펴보기로 한다.

• 센서학회지
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• 제11권2호
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• pp.67-76
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• 2002

본 연구에서는 페라이트 링 코어를 이용한 2차원 fluxgate 센서를 제안하였으며, 본 fluxgate 센서 시스템은 2차원 자장을 측정할 수 있는 센서와 그 센서를 구동하기 위한 구동회로, 그리고 신호처리회로 등으로 구성하였다. 신호 검출 방법으로는 우수고조파 성분 검출을 위해 PSD(phase sensitivity detector) 회로를 사용하였으며, 기존의 제 2고조파 검출법과 비교하기 위해서 pick-up 코일 출력전압의 제 2고조파 성분을 FFT 스펙트럼 분석기를 사용하여 측정하였고, 이렇게 측정된 제 2고조파 성분의 전압과 PSD 단의 출력전압을 비교하였다. 그 결과 여자전류의 증가에 따라 센서의 출력전압도 증가하였으며, 구동주파수에 따른 PSD 단의 출력전압은 주파수가 1.5[kHz]일 때까지는 증가하였지만, 그 이상의 주파수에서는 감소함을 보였다. 그리고 pick-up 코일의 제 2고조파 성분의 전압은 계속 증가함을 보였다. 센서의 최대감도는 구동주파수 1.5 [kHz], 구동전류 2 [App]에서 최대값을 보였으며 감도는 약 1580 [V/T]였다. 센서의 비선형계수는 3 [G] 이내에서 제 2고조파 성분의 전압인 경우 약 1 [%]이내였으며, PSD 단 이후는 약 2.3 [%]이내였다. 그리고 각도오차는 약 ${\pm}2$ [%/FS]이내였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.706-708
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• 2002

Vibration, giving rise to acoustical noise, is an important index of motor performance. The unbalance force due to rotor eccentricity caused by manufacturing imprecision or bearing defects is one possible source of excitation to vibration. With the advent of new high-energy magnetic material together with high precision motor applications, magnetic sources of vibration are becoming more serious. This paper introduces two types of high-speed slotless permanent magnet (PM) machine for electro-mechanical battery and investigates unbalance force due to static eccentricity with finite element method.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.294-296
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• 2002

Considering the application of high temperature superconductor to MRI, the loss at conductor joint would be very important. Therefore, we have carried out a measurement of joint resistance of Bi-2223/Ag tapes at 77 K. A pancake coil was wound by Bi-2223/Ag tape. Both ends the tape were overlapped and soldered to each other. The DC current is induced in the pancake coil by energizing the excitation coil wound by copper wire closely located to the pancake coil. The decay behaviour of the current in coils was clearly separated in two regimes, and initial fast decay of the order of minutes followed by a slow logarithmic-like decay, From this data, the resistance of the joint was evaluated as 2.74 n$\Omega$.

• 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.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.51-54
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• 2005

Generator efficiency optimization is important for economic saving and environmental pollution reduction. In general, the machine loss can be reduced by the decreasing the flux level, resulting in the significant reduction of the core loss. This paper proposesan model-based controller is used to decrement the excitation current component on the basis of measured stator current and machine parameters and the q-axis current component controls the generator torque, by which the speed of the induction generator iscontrolled according to the variation of the wind speed in order to produce the maximum output power. The generator reference speed is adjusted according to the optimum tip-speed ratio. The generated power flows into the utility grid through the back-to-back PWM converter. The grid-side converter controls the dc link voltage and the line-side power factor by the q-axis and the d-axis current control, respectively. Experimental results are shown to verify the validity of the proposed scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.338-340
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• 2003

This paper proposes a stand-alone adjustable speed wind Power generation system using a cage-type induction generator. Indirect vector control is used, where the q-axis current controls the generator speed and the d-axis current controls the excitation level. The generator speed is adjusted according to the wind speed so as to produce the maximum output power. The generated power is charged in the battery bank through ac/dc PWM converter. The proposed scheme has been verified by the experimental results.

• Journal of Power Electronics
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• 제16권4호
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• pp.1612-1620
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• 2016

This paper presents the dynamic excitation control of a siphon-turbine coupled pico-hydro powered cage rotor induction generator and load matching for off-grid electricity generation. Through the proposed dual-role of the current-controlled voltage source converter (VSC), acting as static synchronous compensator and load controller, real and reactive power are dynamically controlled in a decoupled manner with a self supported DC-bus. The proposed scheme entails minimal computation for ensuring the rated (set) capacity of real power. The scheme also exhibits fault immunity for protection, thus enabling the effective handling of constant power electrical loads presented by base telecom station towers in remote locations. The performance of the system is evaluated under MATLAB/Simulink and is experimented through a developed hardware prototype. Simulation and experimental results show close conformity and validate the effectiveness of the proposed scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.100-102
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• 2007

In this paper, a modified multi-level convert for low cost high speed switched reluctance (SR) drive is proposed The proposed multi-level converter has reduced number of power switches and diodes than that of a conventional asymmetric converter for SRM, and lower voltage rating of the dump capacitor comparing with energy efficient c-dump converter. It can supply five operating modes that is boosted, DC-link, zero, negative bias and negative boosted voltage. The proposed multi-level converter has fast excitation and demagnetization modes of phase current, so dynamic response can be achieved. The proposed multi-level converter is verified by computer simulation and experimental results.

• 전기학회논문지
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• 제56권7호
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• pp.1231-1235
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• 2007

This paper presents the dynamic characteristics of a linear brushless dc (BLDC) motor with permanent magnet excitation for the precision conveyor according to the load condition. Dynamic performance of the linear BLDC motor driven with 6 step inverter such as thrust force and speed is simulated by finite element method coupling with external circuit and measured for the prototype motor. The results of finite element analysis are compared to the experimental results and verify reliability.