• 전력전자학회논문지
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• 제5권4호
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• pp.335-342
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• 2000

단상 능동전력필터에 있어서 비선형 부하전류를 직접 검출하지 않고 능통전력필터의 직류측 커패시터 전압을 이용해 추정하여 제어하는 방법을 제안한다. 이는 부하전류와 능동전택필터의 직류측 커패시터 전압을 봉사에 검출하는 기존의 방식에 비해 부하전류 검출단을 제거할 수 있음으로써 설치가 간편할 뿐만 아니라 가격을 낮출 수 있으면서도 동일한 성능의 능동전력필터의 구현을 가능하게 한다. 또한 직류측 커패시터 전압제어를 위해 샘플-흘드와 비례제어빙식을 사용하므로 기존의 저역통괴필터와 PI 제어시 적분기로 인한 지연을 없앨 수 있어 빠르고 우수한 과도응답특성을 나타낸다. 전원전압과 보상전류, 스위치 상태에 따라 8개의 모드로 나누어 능동전력필터의 동작을 설명하였으며, 제안한 방법의 성능을 실험을 통해 확인하였다.

• Journal of Power Electronics
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• 제14권2호
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• pp.383-391
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• 2014

For the digital control of systems such as grid-connected inverters, measuring inverter output currents accurately is essential. However, current measurement offsets are inevitably generated by current measurement paths and cause DC current components in real inverter output currents. Real inverter output currents with DC components cause the DC-link capacitor voltage to oscillate at the frequency of a utility voltage. For these reasons, current measurement offsets deteriorate the overall system performance. A compensation strategy to eliminate the effect of current measurement offsets in grid-connected inverters is proposed in this study. The validity of the proposed compensation strategy is verified through simulations and experiments. Results show that the proposed compensation strategy improves the performance of grid-connected inverters.

• 전기학회논문지P
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• 제67권3호
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• pp.155-159
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• 2018

Recently, the expansion or establishment of facilities for the logistics system is increasing. Conveyor facilities play a major role in sorting and transporting logistics. Induction motors are widely used for the operation of these conveyor systems. In the logistics system, a large number of induction motors are used. These motors have a considerable distance from the power source side and have a low power factor. The installation position for the power factor compensation of the induction motor is very important. Since the voltage drop depends on the length of the line, it is an important parameter in capacitor capacity determination for power factor compensation. The capacity of the capacitors installed to compensate the power factor of the inductive load should be designed to the extent that self-excitation does not occur. In this study, we analyze the method of compensating the proper power factor considering the voltage drop and the installation position of the induction motor in the logistics system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1027-1029
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• 2003

STATCOM which is connected the load parrallel with capacitor. is the reactive power compensation device. In this paper. appling the PSIM(POWERSIM) software to STATCOM system. it is simulated the reactive power compensation of balancing load. And, setting a thoroughly going over it's results. we confirmed the function propriety of developed STATCOM system. So, it will be applied the reactive power compensation experimentation of the developing 30kVA STATCOM at our laboratory.

• ETRI Journal
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• 제45권4호
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• pp.690-703
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• 2023

Multistage amplifiers have become appropriate choices for high-speed electronics and data conversion. Because of the large number of high-impedance nodes, frequency compensation has become the biggest challenge in the design of multistage amplifiers. The new compensation technique in this study uses two differential stages to organize feedforward and feedback paths. Five Miller loops and a 500-pF load capacitor are driven by just two tiny compensating capacitors, each with a capacitance of less than 10 pF. The symbolic transfer function is calculated to estimate the circuit dynamics and HSPICE and TSMC 0.18 ㎛. CMOS technology is used to simulate the proposed five-stage amplifier. A straightforward iterative approach is also used to optimize the circuit parameters given a known cost function. According to simulation and mathematical results, the proposed structure has a DC gain of 190 dB, a gain bandwidth product of 15 MHz, a phase margin of 89°, and a power dissipation of 590 ㎼.

• 한국전자통신학회논문지
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• 제11권11호
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• pp.1053-1060
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• 2016

본 논문은 디지털 능동형 가변 축전기를 사용한 적응형 이퀄라이저를 제안하고 있다. Equalizing amplifier는 주 증폭기와 source degeneration RC 필터로 구성되어 있으며, RC필터를 디지털 능동형 가변 축전기로 구현함으로써 면적 효율을 높이고 선형적인 손실 보상 영역을 확보했다. 능동형 가변 축전기는 miller effect에 의한 임피던스 증가 효과를 사용하였으며, 증폭기 이득 조정을 통해 capacitance의 가변성을 가질 수 있도록 하였다. 시뮬레이션 결과, 능동형 축전기의 선형적 가변 특성을 통해 입력 데이터의 고주파 손실을 보상하여 2Gb/s 전송속도에 대해 0.31 UI의 입력 eye 너비를 0.64 UI로 약 2배 증가시켰다. 적응형 이퀄라이저는 $0.13-{\mu}m\;CMOS$ 공정 값을 사용하여 설계 되었으며, 0.412 mm2 의 레이아웃 면적을 사용한다.

• 전기학회논문지
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• 제65권7호
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• pp.1311-1315
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• 2016

Induction motor requires a rotating magnetic field for rotation. Current required to generate the rotating magnetic field is immediately magnetizing current. This magnetizing current is associated with the reactive power. Induction motor is always required reactive power. If reactive power is supplied only to the power supply side, the power factor is low. Therefore, it is to compensate the power factor by connecting capacitors in parallel to the motor terminal. If the capacitor current is greater than the magnetizing current of the motor, there is a possibility that the self-excitation occurs. High voltage generated by the self-excitation leads to insulation failure on the motor. So it is necessary to calculate the power factor correction capacitor capacity the most suitable to the extent that the magnetizing current does not exceed the capacitor current. In this study, we first computed the magnetization current and the reactive power of the induction motor and then calculates a limit of the maximum power factor by comparing the magnetizing current and the capacitor current installed in order to achieve the target power factor.

• 전기학회논문지P
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• 제58권4호
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• pp.391-396
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• 2009

In this paper, a control algorithm for DC-Link voltage unbalancing compensation of a four-switch inverter for a three-phase BLDC motor drive is proposed. Compared with a conventional six-switch inverter, the split source of the four-switch inverter can be obtained by splitting DC-link capacitor into two capacitors to drive the three phase BLDC motor. The voltages across each of two capacitors are not always equal in steady state because of the unbalance in the impedance of the DC-link capacitors $C_1$ and $C_2$ or the variable current flowed into the capacitor's neutral point in motor control. Despite the unbalance, if the BLDC motor may be run for a long time the voltage across one of the capacitors is more increased. So the unbalance in the capacitors voltages will be accelerated. As a result, The current ripple and torque ripple is increased due to the fluctuation of input current which flows into 3-phase BLDC motor. According to that, the vibration of motor will be increased and the whole system will be instable. This paper presents a control algorithm for DC-Link voltage unbalancing compensation. The sampling from the voltages across each of two capacitors is used to perform the voltage control of DC-Link by using the feedforward controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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• pp.18-20
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• 2007

A coupling capacitor voltage transformer (CCVT) is used in an extra high voltage power system to obtain the standard low voltage signal for protection and measurement. To suppress the effects of ferro-resonance more effectively, a three winding CCVT is used. This paper proposes an algorithm for compensating the secondary voltage of the three winding CCVT. With the secondary voltage of the three winding CCVT, the secondary and tertiary currents are obtained; the primary winding current is obtained by considering non-linear characteristics of the core; the voltage across the capacitor and the inductor are calculated and then added to the measured voltage to compensate the secondary voltage. Test results indicate that the algorithm can reduce the errors of the three winding CCVT significantly.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.58-63
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• 2012

The Test Signal Method is adopted to analyze the impact of thyristor controlled series capacitor (TCSC) on sub-synchronous oscillation. The results show that the simulation system takes the risk of Sub-synchronous Oscillation (SSO) while the TCSC is operating in the capacitive region. A supplementary excitation damping controller (SEDC) is used to mitigate SSO caused by the TCSC. A new optimization method which is aimed for optimal phase compensation is proposed. This method is realized by using the particle swarm optimization (PSO) algorithm. The simulation results show that the SEDC designed by this method has superior suitability, and that the secure operation scope of the TCSC is greatly increased.