• 전기의세계
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• 제31권3호
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• pp.226-234
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• 1982

DC choppers are usually used to control the DC motor by varying the average value of DC input voltage to the DC motors. In this paper, a chopper circuit is suggested and reconstructed by replacing the free-wheeling diode with the parallel capacitor in the conventional ones. It is demonstrated that this chopper circuit with capacitor can reduce the ripples of the output voltage and current in contrast to those of the chopper with diode, and it can be controlled the output waveforms smoothly at high power demand.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.33-35
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• 2003

Capacitor switching is essential for the economic operation, and proper voltage control of KOREA electric utility distribution system. Voltage transients produced by capacitor switching (around 2.0 per unit at substation and 2.5 or less per unit at customer site, and lasting less then 1ms) do not have the magnitude or duration to interfere with the operation of computers, but they do disrupt the operation of adjustable speed drivers. The result of our research, ASD manufacturers should team from the computer industry and design products that will operate satisfactory in the electrical envelopment in which they will be placed. In this case history, the inductors on the input to ADSs in order to prevent nuisance tripping from capacitor switching(and other causes within the apartment) proved to be an effective, low-cost solution.

• Journal of Power Electronics
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• 제19권5호
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• pp.1171-1181
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• 2019

Modular Multilevel Converter (MMC)-based HVDC power transmission using a real-time simulator is one of the key technologies in power electronics research. This paper introduces the design methodology of a physical MMC-HVDC control system based on a Field-Programmable Gate Array (FPGA), which has the advantage of high-speed parallel operation, and validates the accuracy of MMC-HVDC control when operated with a Real-Time Digital Simulator (RTDS). Finally, this paper compares and analyzes the characteristics of capacitor voltage balancing methods such as Nearest Level Control (NLC), NLC with a reduced switching frequency, and tolerance band modulation implemented on physical control system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.316-317
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• 2018

This paper propse the DC link capacitor voltage balancing control for three level neutral point clamped converter with harmonic component injection method. The injcetion voltage consists of harmonic component and DC link capacitor voltage difference. Theoretical analysis is provided to balance the DC link voltage, and it shows that harmonic component compensates the unbalanced condition between the capacitors. Both simulations and experiments are carried out to show that the voltage unbalance have been decreased by the proposed method.

• 전기전자학회논문지
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• 제11권4호
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• pp.315-321
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• 2007

The fast charging photoflash capacitor charger with wide range current limiter is presented. By using proposed control logic block and wide range current limiter, the photoflash capacitor charger can reduce charging time and control life of battery for user convenience. The proposed photoflash capacitor charger has 3s charging time at 3.3V battery voltage, 1.2A current limit condition. It is well-suited for portable device application like digital camera, digital video camera, and mobile phone with camera.

• 대한전자공학회논문지SD
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• 제49권1호
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• pp.15-24
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• 2012

본 논문에서는 Switched-Capacitor 지연 기법의 새로운 고해상도 DPWM 발생기를 사용한 Dynamic-Response-Free SMPS를 제안한다. 제안된 회로는 Switched-Capacitor 지연 기법을 이용한 DPWM 발생기의 내부 커패시터 전압 기울기를 제어하는 방식으로 DPWM의 duty ratio를 결정한다. 제안된 회로는 컨버터의 피드백 전압과 기준전압을 비교하여 DPWM 발생기의 내부 캐패시터에 충방전되는 전류량을 제어하는 방식으로 출력전압 tracking이 가능하다. 따라서 제안된 회로는 기존 closed loop 제어 방식의 SMPS들에서 문제점이 되고 있는 동적 응답특성을 고려할 필요가 없으며, 출력 전압에 overshoot/undershoot로 인한 ringing 현상이 발생하지 않는다는 큰 장점을 가진다. 제안된 회로는 1MHz~10MHz까지 스위칭주파수를 사용자가 선택할 수 있으며, 100MHz의 내부 제어 동작 주파수로 10MHz 최대 스위칭 주파수(DPWM) 발생이 가능하다. 100MHz의 내부 제어 동작 주파수를 사용하여 10MHz 스위칭 주파수 발생시 소모되는 내부 회로의 최대 전류는 2.7mA이며, 출력 버퍼를 포함한 전체 시스템의 전류 소모는 15mA이다. 제안된 회로는 0.125%의 DPWM duty ratio 해상도를 가지고 부하에 최대 1A까지 전류공급이 가능하며, 최대 리플 전압은 8mV이다. 동부하이텍 BCD $0.35{\mu}m$ 공정 파라미터를 이용해 시뮬레이션을 수행하여 제안된 회로의 동작을 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.242-243
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• 2013

This paper presents a voltage and frequency regulation of a Micro-grid using a Battery energy storage system (BESS) and super-capacitor (SPC). The control methods for the both BESS and SPC are proposed to improve the regulation performance and battery life span. The simulation results using the PSCAD/EMTDC are provided to show the effectiveness of the proposed control.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.259-261
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• 2000

UPFC(Unified Power Flow Controller) consists of two voltage sourced converter(VSC)s inserted into AC system through series and parallel coupling transformer, where two VSCs are linked by capacitor at DC-side. Since VSC acts as an AC voltage source behind a reactance, where both magnitude and phase angle of the source are controllable, UPFC can be represented by the equation related to input-output relation of two VSCs. Voltage control of DC-link capacitor provides the path of real power flow between two VSCs. While UPFC is controlled for maintaining the given reference value in steady state, it should be controlled for damping power oscillation in dynamics. For such a control objective, the control strategy based on the energy function was proposed and has been shown to be effect and robust for damping power oscillation of power system. In this paper, UPFC model based on the VSC was analysed and applied to power-flow control and stability analysis. The control strategy based on the energy function is adopted for damping power oscillation of power system. The effectiveness of proposed control strategy was verified by simulation study

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 학술대회 논문집 전문대학교육위원
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• pp.21-25
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• 1999

This paper proposes a novel control strategy of SVC(Static var compensator) using cascade multilevel inverter. To control the reactive power instantaneously, the dq-dynamic system model is described and analyzed. A single pulse pattern based on the SHE(Selective Harmonic Elimination) technique is determined from the look-up table to reduce the line current harmonics and a rotating fundamental frequency switching scheme is applied to adjust the DC capacitor voltage at the scheme level. From the simulation, it is verified that this proposed control scheme make the dynamic control response of SVC fast, the current harmonics low, and the DC capacitor voltage balanced.

• 전력전자학회논문지
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• 제16권4호
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• pp.366-373
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• 2011

펄스파워에서 주로 사용되는 자기스위치는 반복률, 신뢰성, 소자수명에서 우수한 특성을 가진다. 그러나 자기스위치는 현재 대부분 수동으로 조작하여 스위칭 동작을 최적화하고 있으며, 부하가 변동될 경우 스위칭 상태를 자동으로 최적화할 수 없다. 본 논문은 CCPS(capacitor charging power supply)를 이용한 고압펄스 압축용 전원장치의 펄스압축을 위해 사용되는 자기스위치(magnetic switch)의 자동제어 방법을 제안하였다. 자기스위치를 부하변동에 따라 자동으로 제어함으로써 시스템의 에너지 효율을 최적화 할 수 있다. 제안된 방법은 실험을 통하여 검증하였다.