• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.484-488
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• 2000

본 논문에서는 형광등용 인버터에서 발생하는 고조파를 억제할 수 있는 2단 평활랑 콘덴서를 이용한 고효율 고조파 저감회로를 제안한다. 형광등용 인버터에 직류전원으로서 사용되는 전파 전류의 파형은 전압 평활 콘덴서가 충전될 때 입력전압의 최대치 부근에서 펄스형태를 가지는 돌입전류의 발생으로 인해 많은 고조파들을 함유하게 된다. 따라서 이 고조파의 원인이 되는 돌입전류를 억제하기 위하여 본 논문에서는 전단 평활용 콘덴서의 충전전압을 이용하여 입력에서의 갑작스러운 충전전류를 억제하는 방법을 제안하였다. 그 결과 공급전류에서의 고조파의 발생을 억제하여 역율을 개선하게된다. 이에 대한 타당성을 시뮬레이션을 통하여 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.345-353
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• 2013

This paper discusses the experimental results in an effort to understand the tracking and erosion resistance of the micro and nano size $Al_2O_3$ filled silicone rubber (SIR) material which has been studied under the AC voltages, with ammonium chloride as a contaminant, as per IEC 60587 test procedures. The characteristic changes in the tracking resistance of the micro and nano size filled specimens were analyzed through leakage current measurement and the eroded masses were used to evaluate the relative erosion and tracking resistance of the composites. The fundamental, third and fifth harmonic of the leakage current during the tracking study were analyzed using moving average current technique. It was observed that the harmonic components of leakage current show good correlation with the tracking and erosion resistance of the material. The thermogravimetry-derivative thermo gravimetric (TG-DTG) studies were performed to understand the thermal degradation of the composites. The physical and chemical studies were carried out by using scanning electron microscope (SEM), Energy Dispersive X-ray analysis (EDAX) and Fourier Transform Infra-red (FTIR) Spectroscopy. The obtained result indicated that the performance of nano filled SIR was better than the micro filled SIR material when the % wt. of filler increased.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.420-421
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• 2011

In generally, the small harmonic current has not influence on the power system because of offset effect. But the bulk harmonic current has not an offset effect, so that influences on the other customer. This paper describes the measurement power quality in the industrial area, and data analysis result. Also this effect has verified by PACAD/EMTDC simulation tool.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.362-365
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• 1999

In this paper, the method of reducing harmonics and correcting of power factor in single PWM converter associated with diode rectifier and boos converter is studied. The ac-dc converter in which the harmonic distortion in the input current is reduced using a third harmonic injected PWM is proposed. A lower switching power loss and easy configuration o control circuit are obtained by adopting discontinuous current mode. Simulation and experimental results of ac-dc converter with 5[KHz] switching frequency are presented and correction of power factor and reduction of total harmonic distortion was established.

• Journal of electromagnetic engineering and science
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• 제8권3호
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• pp.134-137
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• 2008

This paper proposes a novel quadrature VCO(QVCO) based on direct back-gate second harmonic coupling. The QVCO directly couples the current sources of the conventional LC VCOs through the back-gate instead of front-gate to generate quadrature signals. By the second harmonic injection locking, the two LC VCOs can generate quadrature signals without using on-chip transformer, or stability problem that is inherent in the direct front-gate second harmonic coupling. The proposed QVCO is implemented in $0.18{\mu}m$ CMOS technology operating at 2 GHz with 5.0 mA core current consumption from 1.8 V power supply. The measured phase noise of the proposed QVCO is - 63 dBc/Hz at 10 kHz offset, -95 dBc/Hz at 100 kHz offset, and -116 dBc/Hz at 1 MHz offset from the 2 GHz output frequency, respectively. The calculated figure of merit(FOM) is about -174 dBc/Hz at 1 MHz offset. The measured image band rejection is 46 dB which corresponds to the phase error of $0.6^{\circ}$.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.239-244
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• 2011

Industrial power distribution system includes many kinds of non-linear loads, which produce the harmonics during energy conversion transition. The single-tuned passive filter is widely used to absorb the harmonics and attenuate its undesirable effect in the distribution system. However, the passive filter might be severely stressed, and sometimes even damaged, due to the absorption of harmonics. There is voltage rise on the capacitor when the single-turned harmonic filter is applied. When the capacitor voltage rose above the allowable limit, the expected life of the capacitor will considerably deteriorate. On the other hand, the reactor can experience the spike voltage even if the voltage and current of the capacitor are within the allowable limit, and this accumulated voltage stress of the reactor causes its premature fault. In this paper, we analyzed and compared the harmonic voltage and current of the reactor and capacitor in a single-tuned harmonic filter through the EMTP software and verified them with the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.147-148
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• 2006

Recently, due to increasing the application of power electronic equipment, harmonics generated from the non-liner load are fairly produced. Harmonics can cause a variety of problems such as the overheating of distribution transformer, the breakdown of device and communication interference. Interest about power quality decline of power system is very increased. In this paper, we are measured the harmonic voltage and current o( power system to analyze harmonic characteristics, and it is analyzed Total Harmonic Distortion(THD). Also, we Ere modeled power system using PSCAD/EMTDC. And it is analyzed harmonic voltage and current in steady-state. The study results have been indicated the utility about harmonics analysis and modelling for power system.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.358-365
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• 2012

A new third harmonic injection circuit for light-emitting diode (LED) drivers is proposed to eliminate electrolytic capacitors and thereby extend the lifetime of LED drivers. When a third harmonic current is injected to the input current of the LED driver, the required capacitance of the driver can be reduced. The proposed circuit can control an injection ratio and has simple circuitry. The synchronous third harmonic is generated by a phase locked loop (PLL), a 1/3 counter, and op-amps and applied to a power factor correction circuit. Thus, the storage capacitor can install film capacitors instead of the electrolytic capacitor. The value of storage capacitance can be reduced to 78% compared to an input power factor of 100%. The proposed circuit is applied to the 80W prototype LED driver to experimentally verify the performances.

• Journal of Power Electronics
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• 제12권5호
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• pp.830-841
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• 2012

Active power filters (APF) can be employed for harmonic compensation in power systems. In this paper, a fuzzy based method is proposed for identification of probable APF nodes of a radial distribution system. The modified adaptive particle swarm optimization (MAPSO) technique is used for final selection of the APFs size. A combination of Fuzzy-MAPSO method is implemented to determine the optimal allocation and size of APFs. New fuzzy membership functions are formulated where the harmonic current membership is an exponential function of the nodal injecting harmonic current. Harmonic voltage membership has been formulated as a function of the node harmonic voltage. The product operator shows better performance than the AND operator because all harmonics are considered in computing membership function. For evaluating the proposed method, it has been applied to the 5-bus and 18-bus test systems, respectively, which the results appear satisfactorily. The proposed membership functions are new at the APF placement problem so that weighting factors can be changed proportional to objective function.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.351-352
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• 2015

This paper proposed a new control strategy for voltage source inverter (VSI) of effective fifth and seventh harmonic reduction in the point of common coupling (PCC) in islanded microgrid under nonlinear load without any additional hardware devices. The non-linear load regularly causes such harmonic distortion, which harmfully affect the performance of other loads or other distributed generation (DG) sources connect to the PCC. In order to improve the quality of delivered output voltage, these harmonic must be rejected. The proposed control strategy is developed based on the current controller formed by resonant controller parallel with a proportional integral controller, which perform on the fundamental reference frame. The reference current is estimated based on the voltage harmonic and the injecting power. The simulation and experimental results are shown to verify the effectiveness of proposed control method.