• 한국통신학회논문지
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• 제27권10C호
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• pp.993-998
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• 2002

전력증폭기에서는 특유의 비선형 특성에 의해 출력에 왜곡이 발생하므로 이를 보상할 수 있는 방안을 강구하여야 한다. 본 논문에서는 쇼트키 다이오드를 직렬로 삽입한 전력증폭기용 프리디스토터의 특성에 관하여 연구하였다. 이를 통해 쇼트키 다이오드의 비선형 특성을 이용한 프리디스토터를 전력증폭기 전단에 삽입하면 전력증폭기를 선형화 시킬 수 있음을 확인하였다. 즉, 입력 신호 레벨이 낮으면 입력된 신호는 전력증폭기로 그대로 들어가지만 입력 신호레벨이 높으면 프리디스토터에서 감쇄되어 전달된다. 그러므로 전력증폭기는 항상 saturation 영역에서만 동작하게 된다. Serenade 8.0을 이용하여 모의 실험을 통해 약 3% 가량의 효율이 개선됨을 확인할 수 있었다. 또한 500MHz에서 2.2㎓까지의 대역 중 1.8㎓ 대역에서 가장 확실한 비선형특성을 얻을 수 있음을 확인하였다.

• 전력전자학회논문지
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• 제7권1호
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• pp.18-29
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• 2002

기존의 역률 개선 컨버터는 경 부하에서 높은 직류 링크 전압을 갖는다. 특히 라인 전압이 높고 부하가 작을 경우, 직류 링크 전압은 매우 높은 전압을 갖게 되어 실용상 문제가 존재한다. 본 논문에서 역률 개선 부로 벅 토폴로지를 갖는 새로운 단일 전력 단 역률 개선 컨버터를 제안하였다. 또한 제안된 컨버터의 타당성을 증명하기 위해 제안된 회로의 설계 예를 보였으며, 설계 시 고려되어야 할 사항들과 관련 설계 식을 유도하였다. 유도된 설계 식으로부터 정해진 회로 정수 값을 이용하여 실험을 실시하였고, IEC1000-3-2의 역률 규제를 만족함을 입증하였다. 본 논문에서 제안된 컨버터를 통하여 기존의 단일 전력 단 컨버터의 문제점인 경 부하 시 높은 직류 링크 전압 문제를 해결할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.401-406
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• 2004

In this paper, a new time-domain adaptive predistortion scheme is proposed to compensate for the nonlinearity of high power amplifiers (HPA) in OFDM systems. A complex Wiener-Hammerstein model (WHM) is adopted to describe the input-output relationship of unknown HPA with linear dynamics, and a power series model with memory (PSMWM) is used to approximate the HPA expressed by WHM. By using the PSMWM, the compensation input to HPA is calculated in a real-time manner so that the linearization from the predistorter input to the HPA output can be attained even if the nonlinear input-output relation of HPA is uncertain and changeable. In numerical example, the effectiveness of the proposed method is confirmed and compared with the identification method based on PSMWM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.359-360
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• 2016

This paper presents a new predictive current control (PCC) method to achieve the coordinate control of power and current of the matrix converter under unbalanced input voltages. In order to control the power fluctuation in the input side, the flexible source current reference is generated based on the positive-negative sequence components of the input voltage. The optimal switching state to adjust source and load currents is selected by minimization the cost function which is obtained from the sum of the absolute errors between the current references and their predictive values. Simulation results are given to validate the effectiveness of the proposed PCC method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.243-246
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• 1997

In this paper, soft switching high power factor buck converter is proposed. This converter is composed of diode rectifier, a input capacitor can be small enough to filter input capacitor can be small enough to filter input current, buck converter with loss less snubber circuit. Converter is operated in discontinous conduction mode, turn of of the switching device is a zero current switching(ZCS) and high power factor input is obtained. In addition, zero voltage switching(ZVS) at turn of is achieved and switching loss is reduced using loss less snubber circuit. The capacitor used in the snubber circuit raised output voltage. Therefore, proposed converter has higher output voltage and higher efficiency than conventional buck type converter at same duty factor in discontious conduction mode operation.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.126-128
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• 1993

Rectifiers of power conversion system are widely used condenser at input to be cheap and to be simple construction. But this method is produced harmonics of pulse at peak value of input AC voltage. The main circuit which make input current of a sinusoidal wave and improve power-factor is almost taken step-up converter. This paper is able to obtain high power-factor and efficiency because the input current is made sinusoidal wave in single phase alternating current(AC) source. Also the proposed converter is able to minimize switching loss by ZVCS(zero voltage switching and zero current switching).

• 전자공학회논문지S
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• 제34S권6호
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• pp.77-84
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• 1997

buck type converter doesn't appear when an input voltag eis lower than an output voltage. This is the main reason the buck converter has not been used for high power factor converters. In this paper, soft switching high power factor buck converter is proposed. This converter is composed of diode rectifier, input capacitor can be small enough to filter input current, buck converter with loss less snubber circuit. Converter is operated in discontinous conduction mode, turn on of the switching device is a zero current switching (ZCS) and high powr factor input is obtianed. In addition, zero voltage switching (ZVS) at trun off is achieved and switching loss is reduced using loss less snubber circuit. The capacitor used in the snubber circuit raised output voltage. Therefore, proposed converter has higher output voltage and higher efficiency than conventional buck type converter at same duty factor in discontinous conduction mode operation. High power factro, efficiency, soft switching operation of proposed converter is veified by simulation using Pspice and experimental results.

• 한국안전학회지
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• 제15권2호
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• pp.92-96
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• 2000

In this experiment, we studied about concentration characteristics of $NO_x$ and generation of ozone in the reactor of corona discharge type by using mixed gas of $NO/N_2$ and $N_2/O_2$. In the case of the initial NO concentration increased, decrease rate of NO concentration was weakened and discharge input power of minimum NO concentration became high. When NO concentration was high, NO decomposition limit was appeared. And NO reduction rate was decreased, when initial NO concentration and discharge input power increased. When discharge input power was 5W, we could know the most proper energy value for treatment of NO. When the concentration of initial NO increased, generation of ozone decreased and in the case of same concentration of NO, according to discharge input power increase, generation of ozone increased.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.107-111
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• 2001

This paper presents a detailed analysis method of the universal input forward converter with LC input filter operating in discontinuous capacitor voltage mode(DCVM) for wind power generation. In this analysis, condition for DCVM operation and conversion ratio for rectified sinusoidal input are made clear. To verify the validity of the analysis, simulation is carried out for the universal input ranging from 90 $V_{rms} to 260 V_{rms}$