• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.207-210
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• 1995

In this paper, two representative schemes for vector control of induction motor without speed sensor are studied. First, the two sensorless systems which are implemented by voltage and current source are presented with new ideas and interpretations. Then a linear model around an operating point is proposed. Finally, the stability improvement of these systems are studied and evaluated by computing the trajectories of poles and zeros.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2354-2363
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• 2018

This paper proposed a novel double closed control strategy for single-phase voltage source pulse width modulation (PWM) rectifier based on active disturbance rejection control (ADRC) and dq current decoupling control. First, the mathematical model of the single-phase PWM rectifier in the d-q axis synchronous rotating reference frame is established by constructing a virtual component using a second-order generalized integrator (SOGI). Then, the mathematical model is simplified according to the active power conservation, and the first-order equation of single-phase PWM rectifier voltage outer loop is acquired. A linear auto-disturbance rejection controller is used to design the voltage outer loop according to the first-order equation. Finally, the proposed control strategy and the traditional PI control are compared and verified by simulation and physical experiments. Both simulation and experimental results confirm that the proposed control strategy has excellent dynamic performance and strong rejection ability to disturbances.

• 대한전기학회논문지
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• 제39권5호
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• pp.453-461
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• 1990

In this paper, a short primary-short secondary single-sided linear induction motor which is used as the driving source for an automatic conveyor system, is selected as an analysis model. The finite element method in which the current vector potential is introduced is adopted to analyze the eddy current distribution and thrust force which are produced according to the relative position of the primary and the secondary. Also, the analysis results are compared with experimental ones, to show the propriety of this model.

• 전자공학회논문지
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• 제52권12호
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• pp.109-117
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• 2015

본 논문에서는 DSP(Digital Signal Processor)를 이용하여 LED(Light Emitting Diode)에 전류 또는 전압을 공급하고, 이에 따라 나타나는 전압 또는 전류 특성을 분석하는 시스템에서, 전원 공급 또는 측정하는 회로의 비선형 오차 및 임의로 발생하는 오차를 감소시키는 방법을 제안하였다. 임의 오차를 줄이기 위해서는 재귀 평균 방법을 이용하였으며, 비선형 오차를 줄이기 위해서는 보정과정에서 획득한 데이터들을 2차 다항 회귀분석 방법을 이용하여 보정계수를 구하였으며, 이를 이용하여 LED를 생산 시 측정하는 항목인 역방향전류(IR), 역방향 전압(VR), 순방향전압(VF1, VF2, VF3)에 적용하여 오차를 교정하였다. 실험 결과에서는 오차율이 0.017 ~ 0.043 %로 관찰되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.44-45
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• 2007

This paper deals with error compensation in current transformers. Since the exciting current can be considered as the main error source, its evaluation can allow the compensation of its detrimental effects to be obtained. The exciting current required by the transformer in every king of steady state operation can be determined by simply acquiring the secondary current, provided that the examined CT has been preliminarily identified. This paper also proposed a new approach to the model of the exciting branch. The exciting branch can be divided into a non-linear core loss resistor, and a non-linear magnetizing inductor whose flux and current characteristic is not the same as the characteristic shown by the joined tips of the first quadrant of a family of hysteresis loops. The performance of the proposed algorithm was validated under various conditions using EMTP generated data. Test result show, in all cases an improvement in primary current reproduction accuracy, compared with that achieved using CT's ratio.

• 조명전기설비학회논문지
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• 제24권11호
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• pp.9-16
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• 2010

This paper examines the temperature characteristics of an Optical CT (optical current transformer) using the Faraday effect for measuring high current in a super high voltage-power apparatus. It is performed as follows by the sensor for embodying Faraday effect. $\cdot$ A single-mode optical fiber capable of maintaining a polarization state is used. $\cdot$ A light source is applied at 1310[nm] to a Laser Diode. $\cdot$ The Linear of Faraday effect to a large current is evaluated and $\cdot$ A possible application using an Optical CT was shown. An Influence of Faraday effect to the surrounding temperature measured -40~50[$^{\circ}C$], and the characteristic of the current sensitivity was reported. An application using the results of the temperature compensation system was used in order to compensate for surrounding temperatures. A possibility of applying Optical CT for electric power apparatus was advanced further. We were able to confirm that this temperature calibration method can minimize the fluctuation of the output signal depending on the temperature conditions.

• 조명전기설비학회논문지
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• 제27권3호
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• pp.55-64
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• 2013

In this paper, a new topology which can add a small reactor in series to a condenser-bank type reactive power compensator to limit current is proposed. And also the proposed topology can add or remove a power condenser safely without any addition of inrush-current suppression resistance. The proposed method tests variable resistance of the drain source of a switching device which is controlled by gate voltage in a two-way switch with a diode rectifier and FET switch. In other words, the proposed method is a inrush-current suppression method with the structure of variable resistance. In particular, the proposed method creates smooth current without any resonance in inrush-current as well as is not limited by the time of switch on and off.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.75-82
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• 2015

This paper presents a new technique for enhancing power quality by reducing harmonics in the neutral conductor. Three-Phase Four-Wire (3P4W) system is commonly used where single and three phase loads are connected to Point of Common Coupling (PCC). Due to unbalance loads, the 3P4W distribution system becomes unbalance and current flows in the neutral conductor. If loads are non-linear, then the harmonic content of current will flow in neutral conductor. The neutral current that may flow towards transformer neutral point is compensated by using a series active filter. In order to reduce the harmonic content, the series active filter is connected in series with the neutral conductor by which neutral and phase current harmonics are reduced significantly. In this paper, solar PV based inverter circuit is proposed for compensating neutral current harmonics. The simulation is carried out in MATLAB/SIMULINK and also an experimental setup is developed to verify the effectiveness of the proposed method.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.682-684
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• 2004

Random Telegraph Signal(RTS)에 의한 1/f 잡음이 CMOS Ring Oscillator의 Phase Noise와 Jitter에 미치는 영향을 조사한다. 7단 Ring Oscillator의 각 노드에 병렬 연결된 10개의 Piece-Wise-Linear 전류원이 RTS 신호를 모델링 한다. RTS 전류원의 진폭과 Time Constant를 변화시키면서 Ring Oscillator 출력의 FFT 및 전력 스팩트럼 밀도, Jitter를 관찰한다. RTS 전류원의 진폭은 Phase Noise의 폭을 증가시키고 결과적으로 Jitter의 크기도 증가 시키는 것이 확인 되었다. 그리고 RTS Time Constant가 짧아질수록 출력 신호의 FFT peak의 폭이 커지고 Cycle to Cycle Jitter 값이 증가하였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.172-178
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• 2003

As a typoon gets into harbour, a moored ships shows erratic motions and even mooring line failures is occurred. Such troubles may be caused by harbour resonance phenomena, result in large motion amplitudes at law frequency, which is closed to the natural frequency of the moored ship. The nonlinear motions of a moored ship beside quay are simulated under external forces due to wave, current including mooring forces in time domain. The forces due to waves are obtained from source and dipole distribution method in the frequency domain. The current forces are calculated by using slow motion maneuvering equation in the horizontal plane. The wind forces are calculated from emperical formula of ABS and the mooring forces of ropes and fenders are modeled as linear spring.