• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2549-2552
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• 1999

The fictitious power theory in time domain is very easy to understand, but power analyzing time of active power is increased, because power is analyzed using signal techniques based on the correlation between voltage and current waveforms. Also, conventional methods in time/frequency domain to evaluate the compensation performance of active power filters are not provided easy solutions. So, the authors have previously proposed 3-D current coordinates which is composed into active component, fundamental reactive component and distorted component of nonlinear loads current. This method has excellent performance, but can not evaluate the characteristics of nonlinear load current whether inductive or capacitive. Therefore, To overcome problems mentioned previously, this paper deals with the simple instantaneous power theory and the modified 3-D current coordinates for evaluating the compensation performance of active power filters. To confirm the validity, active power filters simulator is developed using C-language. From the simulation, results are discussed their utility.

• 대한전자공학회논문지TE
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• 제42권3호
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• pp.39-44
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• 2005

본 논문에서는 견실한 전력선 통신을 위한 5-ary 주파수 편이 키잉 방식을 사용하였다. 5-ary 캐리어중 3 캐리어는 데이터를 송신하기 위해서 사용하는 주파수이며, 115kHz, 120kHz, 125kHz으로, 각각 0.33ms의 송신시간을 할당해 총 영교차점을 기준으로 하여 1ms를 송신을 한다. 수신측에서는 채널 상태를 파악할 수 있는 더미 캐리어를 50kHz, 350kHz를 각각 0.5ms 씩 총 1ms를 추가하였다. 실험 결과 칩 방식과 비교해 볼 때 영 교차점에서의 주파수 천이 키잉 방식이 용량성 부하에 대해 적은 송신 전력으로 더 나은 성능을 가진다.

• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.566-570
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• 2008

Vertical nanowire SGFETs(Surrounding Gate Field Effect Transistors) provide full gate control over the channel to eliminate short channel effects. This paper presents design and characterization of a differential pair amplifier using NMOS and PMOS SGFETs with a 10nm channel length and a 2nm channel radius. The amplifier dissipates $5{\mu}W$ power and provides 5THz bandwidth with a voltage gain of 16, a linear output voltage swing of 0.5V, and a distortion better than 3% from a 1.8V power supply and a 20aF capacitive load. The 2nd and 3rd order harmonic distortions of the amplifier are -40dBm and -52dBm, respectively, and the 3rd order intermodulation is -24dBm for a two-tone input signal with 10mV amplitude and 10GHz frequency spacing. All these parameters indicate that vertical nanowire surrounding gate transistors are promising candidates for the next generation high speed analog and VLSI technologies.

• Journal of Electrical Engineering and Technology
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• 제5권4호
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• pp.552-560
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• 2010

This paper presents an application of layered Artificial Neural Network controller to study load frequency control problem in power system. The objective of control scheme guarantees that steady state error of frequencies and inadvertent interchange of tie-lines are maintained in a given tolerance limitation. The proposed controller has been designed for a two-area interconnected power system. Only one artificial neural network controller (ANN), which controls the inputs of each area in the power system together, is considered. In this study, back propagation-through time algorithm is used as neural network learning rule. The performance of the power system is simulated by using conventional integral controller and ANN controller, separately. For the first time comparative study has been carried out between SMES and CES unit, all of the areas are included with SMES and CES unit separately. By comparing the results for both cases, the performance of ANN controller with CES unit is found to be better than conventional controllers with SMES, CES and ANN with SMES.

• 조명전기설비학회논문지
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• 제12권2호
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• pp.21-28
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• 1998

본 연구는 산업계에서 많이 사용되고 잇는 3상 브리지 다이오드 정류기에서 입력측에 발생하는 고조파 문제를 개선하고자 한다. 다이오드 방식은 제어기가 필요치 않기 때문에 간단하고 높은 신뢰성을 갖지만 입력단 전류의 불연속성으로 인하여 전류파형의 왜곡이 생긴다. 본 연구에서는 기존의 3상 브리지 다이오드 정류기에 부가적으로 부착 가능한 3개의 스위치를 제안하여 매순간 3상의 전류 중에서 다이오드 정류기로 흐르지 못한 한 상의 전류를 제안한 스위치를 통하여 흐르게 하여 전류가 연속적으로 흐르게 하였다. 연속적인 전류의 흐름은 고조파 성분을 감소시키며 역률 또한 개선시키는 것을 모의 실험과 실험을 통하여 입증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.26-28
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• 2005

Induction generator is the most common generator in wind energy systems because of its simplicity, ruggedness, little maintenance, price and etc. But the main drawbacks in induction generator is its need of reactive power means to build up the terminal voltage. This drawback is not an obstacle today where PWM inverters can accurately supplies the induction generator with its need from reactive power. For a insurance of three-phase induction generator requires capacitive reactance of the terminal. Most of previous work uses numerical iterative method to determine this minimum capacitor. But the numerical iteration takes long time and divergence may be occurs. In this paper is presented the design methods of the minimum self-excited capacitor required for induction generator operation. And a new formula from the equivalent circuit for stable generation operation of self-excited induction generator calculates the proper capacity to obtain the terminal voltage of the load stage. The validity of proposed design methods is confirmed by experimental and computed results.

• Journal of Power Electronics
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• 제19권3호
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• pp.637-644
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• 2019

Wireless power transfer (WPT) technology with various transfer mechanisms such as inductive coupling, magnetic resonance and capacitive coupling is being widely researched. Until now, power transfer efficiency (PTE) and power transfer capability (PTC) have been the primary concerns for designing and developing WPT systems. Therefore, a lot of studies have been documented to improve PTE and PTC. However, power consumption in the standby mode, also defined as the no-load mode, has been rarely studied. Recently, since the number of WPT products has been gradually increasing, it is necessary to develop techniques for reducing the standby power consumption of WPT systems. This paper investigates the standby power consumption of commercial WPT products. Moreover, a standby power reduction technique for WPT systems via magnetic resonance coupling (MRC) with a parallel resonance type resonator is proposed. To achieve a further standby power reduction, the voltage control of an AC/DC travel adapter is also adopted. The operational principles and characteristics are described and verified with simulation and experimental results. The proposed method greatly reduces the standby power consumption of a WPT system via MRC from 2.03 W to 0.19 W.

• Journal of Advanced Marine Engineering and Technology
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• 제39권9호
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• pp.940-946
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• 2015

본 논문에서는 300kHz 이상의 주파수를 사용하는 고전압펄스의 출력이득을 증폭시키는 방법에 대하여 고찰하였다. 종래의 파워스테이지의 전압을 상승시켜 펄스진폭(Pulse-amplitude)을 증폭하는 방식 대신에, 부하의 용량성분과 회로의 기생성분간의 공진을 이용하여 출력이득을 증폭하는 방식으로 연구가 진행되었다. 특히 브릿지형 대신에 Flyback Topology를 적용을 통하여 회로구성을 간소화하고, 출력펄스파형에 출력전극의 용량성분을 부여함에 따라 부하에 가해지는 출력전압의 이득을 증폭시킴으로써, 하드스위칭을 통한 출력회로 내에서의 과부하 및 발열에 따른 손상을 막을 수 있는 장점이 있다. 해당연구는 의료 및 산업용가열분야에 적용되는 유전가열 방식의 접촉형 가열기기의 공간적, 전기적 효율을 제고할 수 있는 한 방법을 제시한다.

• Journal of Power Electronics
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• 제15권5호
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• pp.1305-1317
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• 2015

Distributed generation systems (DGSs) have been getting more and more attention in terms of renewable energy use and new generation technologies in the past decades. The self-excited induction generator (SEIG) occupies an important role in the area of energy conversion due to its low cost, robustness and simple control. Unlike synchronous generators, the SEIG has to absorb capacitive reactive power from the outer device aiming to stabilize the terminal voltage at load changes. This paper presents a novel static VAR compensator (SVC) called a magnetic energy recovery switch (MERS) to serve as a voltage controller in SEIG powered DGSs. In addition, many small scale SEIGs, instead of a single large one, are applied and devoted to promote the generation efficiency. To begin with, an expandable mathematic model based on a d-q equivalent circuit is created for parallel SEIGs. The control method of the MERS is further improved with the objective of broadening its operating range and restraining current harmonics by parameter optimization. A hybrid control strategy is developed by taking both of the stand-alone and grid-connected modes into consideration. Then simulation and experiments are carried out in the case of single and double SEIG(s) generation. Finally, the measurement results verify that the proposed DGS with SVC-MERS achieves a better stability and higher feasibility. The major advantages of the mentioned variable reactive power supplier, when compared to the STATCOM, include the adoption of a small DC capacitor, line frequency switching, simple control and less loss.

• 조명전기설비학회논문지
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• 제13권3호
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• pp.64-72
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• 1999

종랭의 시간영역에서의 가상전력이론은 기본파 무효전력성분의 계산시, 전압과 전류의 상호상관함수 알고리즘이 이용되며, 이는 많은 시간과 기억용량이 필요하게 되므로 DSP(Digral Signal Process)에 의해서만 비로소 실시간 전력분석 및 제어가 가능하게 된다.또한 3차원 전퓨 좌표계에 의한 종래의 능동전력필터의 보상성능 평가법은 평가대상의 부하전류가 유도성인지 용량성 인지 평가할 수 없는 단점이 있었다. 따라서 본 연구에서는 종래의 시간영역에서의 가상전력이론에 비하여 비교적 전력을 간단히 분석할 수 있는 평균전력이론을 제안하고, 유도성 부하 및 용량성 부하에도 모두 적용 가능한 능동전력필터의 수정된 보상성능 평가법을 제시하였다. 종래의 시간영역에서의 가상전력이론과 비교하여 제안된 방법이 동일한 결과를 얻으면서 DSP등이 필요치 않는 간단한 알고리즘을 C-언어에 의한 시뮬레이터로 그 가능성을 확인하였다.