• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.588-590
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• 1996

An AC induction motor or constant speed characteristics has been widely used as power source because of simple structure and low maintenance cost in industrial field. The variable frequency AC source with a conventional inverter which is composed or power semi-conductors and drive systems contains much noises in sine wave current due to high speed switching or direct current. In this paper, the low pass LC filter for a variable speed induction motor driven by a full bridge inverter is introduced to solve EMI problem originated by much noise current. The modified LC filter based on the 3rd order Butterworth LC filter is used for the computer simulations and real experiments. The characteristics or proposed LC filter are investigated through FET analysis.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.163-167
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• 2000

This paper presents the digital control of single-phase power factor correction(PFC) converter which has the variable gain according to the condition of inner control loop error. Generally the gain of inner current control loop in single-stage PFC converter has a constant magnitude. This has a bad influence on the power factor because current loop doesn't operate smoothly in the condition that input voltage is low In particular a digital controller has more time delay than an analog controller and degrades This drops the phase margin of the total digital PFC system,. It causes the problem that the gain of current control loop isn't increased enough. In addition the oscillation happens in the peak value of the input voltage open loop PFC system gain changes according to ac input voltage. These aspects make the design of the digital PFC controller difficult The digital PFC controller presented in this paper has a variable gain of current control loop according to input voltage. The 1kW converter was used to verify the efficiency of the digital PFC controller.

• 한국조명전기설비학회지:조명전기설비
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• 제8권3호
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• pp.36-43
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• 1994

본 연구는 교류전원측에서 콘버터에 의해 출력전압조정과 동시에 입력전류가 전압과 동상에 가까운 정현파가 되도록 하기 위해 고주파 스위칭에 의한 단상 부스터 콘버터의 제어방식을 분석하고 가변밴드폭 제어방식에 의해 1[kW]부하에 대하여 각 파라메타를 산정하며 실험장치를 구성하여 주파수 스팩트럼 분석기에 의한 분석을 토대로 고역률 동작을 확인하고자 한다.

• 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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• 제13권4호
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• pp.1558-1565
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• 2018

Three-phase current is reconstructed from the dc-link current in an AC machine drive with a single current sensor. Switching pattern modification methods, in which the magnitude of the effective voltage vector is secured over its minimum, are investigated to accurately reconstruct the three-phase current. However, the existing methods that modify the switching pattern cause voltage and current distortions that degrade sensorless performance. This paper proposes a variable-magnitude voltage signal injection method based on a high frequency voltage signal injection. The proposed method generates a voltage reference vector that ensures the minimum magnitude of the effective voltage vector by varying the magnitude of the injection signal. This method can realize high quality current reconstruction without switching pattern modification. The proposed method is verified by experiments in a 600W Interior permanent magnet synchronous machine (IPMSM) drive system.

• 조명전기설비학회논문지
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• 제20권10호
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• pp.35-40
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• 2006

이 논문에서는 주파수 가변형 무선 personal area network(PAN) 통신시스템 및 단말에 적용이 가능한 응용 회로로써, 탭계수(tap coefficient) 회로를 가변시련 수 있는 전류모드 아날로그 finite impulse response (FIR) 필터를 제안한다. 가변되는 7-tap FIR 필터의 동작은 컴퓨터 모의실험으로부터 확인하였고, $0.8[{\mu}m]$ CMOS 공정기술을 사용하여 0.0625-step 탭계수 회로가 제작되었다. 제안된 FIR 필터는 탭계수의 길이와 계수를 가변시킬 수 있기 때문에 주파수 가변형 무선 PAN통신 시스템 및 단말기에 적용 가능한 유용한 특성을 갖는다.

• 한국산업정보학회논문지
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• 제18권5호
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• pp.1-8
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• 2013

본 논문은 수동소자를 사용하지 않고 선형성 향상을 얻는 가변이득증폭기(VGA, variable gain amplifier) 설계에 관련된 것이다. 이 제안된 VGA는 전류 귀환 증폭기 구조를 이용하고, 이득은 입력단과 귀환부의 트랜스컨덕턴스(GM) 비로 얻어진다. 선형성과 높은 이득을 얻기 위하여 귀환 트랜스컨덕턴스에 전류 분할 기법과 소스 축퇴(degeneration) 기법을 사용하였다. 이득의 변화는 가변 정류기로 입력 트랜스컨덕턴스의 바이어스 전류를 변화시켜 얻을 수 있다. 이 VGA는 $0.35{\mu}m$ CMOS공정을 사용하여 설계하였고, 저 전력을 위해 sub-threshold 영역에서 동작시키게 하였다. 가변 이득은 23dB~43dB의 결과를 얻도록 하였고, 소모 전류는 3.3V에서 $2.82{\mu}A{\sim}3{\mu}A$ 이다. 이 VGA가 차지하는 칩 면적은 $120{\mu}m{\times}100{\mu}m$이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.550-553
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• 2002

A source meter is a basic instrument to perform a measurement of DC characteristic of semiconductor devices. the source meter can be used as variable voltage source, variable current source, voltage meter, or current meter. The accuracy of the low current measurement can be improved with the compensation of leakage current and charge and discharge current. In the low current measurement, the RC time constant is extremely big, so the measurement speed is very low. In this thesis, the analysis of the behavior of the measurement current according to the RC time constant and output capacitance and the method to accelerate the measurement speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.525-527
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• 1996

Hysteresis current control is one of the simplest techniques used to control currents for high speed drive systems, because of its simplicity of implementation, fast current control response, and inherent peak current limiting capability. However the conventional fixed-band hysteresis control has a variable switching frequency throughout the fundamental period, and consequently the load current harmonics spreaded on the wide frequency range. In this paper, a simple, novel alterative approach is proposed for a variable-hysteresis band current controller which uses feedback techniques to achieve constant switching frequency with good dynamic response. The method is easily implemented in hardware, the resultant controller is easily tuned to a particular load, and has good immunity to variation in PV parameter and dc supply voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.116-118
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• 1995

A comprehensive analytical study of total-intake current waveforms is described. In particular, the characteristics of the modulation envelope of the waveforms are the subject of detailed investigation. It is shown that the lower modulation envelope of the total intake current is capable of providing a signal suitable for use in stabilising a variable-reluctance stepping motor.