• 조명전기설비학회논문지
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• 제25권4호
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• pp.57-64
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• 2011

Most of the user has been used linear load and non-linear load. The former is usually inductive load which is needed power factor compensation, the latter is power conversion system device. Actually two kinds of load is used together in the customer application. Generally capacitor is used for power-factor compensation of inductive load and reduction harmonics of non linear load with reactor. Non-linear load generates harmonic current for its energy conversion process. If harmonic current pass along the low impedance side of distribution system, the magnification of voltage and current is appeared by the series and parallel resonance. As a result, condenser has received a bitter electrical stress by the harmonic component. In this paper, we analyzed that how resonance is changed by the 5-th harmonic current pattern and proposed an alternative plan for non-magnification.

• 전기의세계
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• 제29권12호
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• pp.791-797
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• 1980

This paper is concerned with the study of improving the faults of phase control scheme and suggesting a new approach to the control of load circuit with AC source. AC current control can restrict the magnitude of current within the given upper and lower current and make current continuous during every cycle. Also the harmonic contents of current can be greatly reduced using this control scheme. Analog computer and digital computer simulations reveal that the current control scheme is superior to the phase control scheme in controlling the power supply to the load R-L. Experimintal results demonstrate the feasibility and verify the operation of current controlled system.

• Journal of Power Electronics
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• 제4권2호
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• pp.87-95
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• 2004

A new fast-response high-current clamp DC-DC converter circuit design is presented that will meet the requirements and features of the new generation of microprocessors and digital systems. The clamp in the proposed converter amplifies the current in case of severe load changes and is able to produce high slew rate of output current and capability to keep constant the output voltage. This proposed high-current clamp technique is theoretically loss less, low cost and easy to implement with simple control scheme. This is modified from a basic buck topology by replacing the output inductor with two magnetically coupled inductors. Inductors are difference in inductance, one has large inductance and other has small inductance. The inductor with small inductance will take over the output inductor during fast load transient. It speedup the output current slew rate and reduce the output voltage drop in the case of heavy burden load changes.

• 한국초전도ㆍ저온공학회논문지
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• 제19권3호
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• pp.44-48
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• 2017

Current lead is a device that connects the power supply and superconducting magnets. High temperature superconductor (HTS) has lower thermal conductivity and higher current density than normal metal. For these reasons, the heat load can be reduced by replacing the normal metal of the current lead with the HTS. Conventional HTS current lead has same cross-sectional area in the axial direction. However, this is over-designed at the cold-end (4.2 K) in terms of current. The heat load can be reduced by reducing this part because the heat load is proportional to the cross-sectional area. Therefore, in this paper, heat load was calculated from the heat diffusion equation of HTS current leads with uniform and non-uniform cross-sectional areas. The cross-sectional area of the warm-end (65K) is designed considering burnout time when cooling system failure occurs. In cold-end, Joule heat and heat load due to current conduction occurs at the same time, so the cross-sectional area where the sum of the two heat is minimum is obtained. As a result of simulation, current leads for KSTAR TF coils with uniform and non-uniform cross-sectional areas were designed, and it was confirmed that the non-uniform cross-sectional areas could further reduce the heat load.

• 전력전자학회논문지
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• 제14권5호
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• pp.379-386
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• 2009

ITER 핵융합 장치에 사용되는 Vertical Stabilization(VS) 컨버터는 4상한 운전 모드의 대용량 부하에 전력을 공급하기 위해서 4개의 직렬구조 12펄스 컨버터를 역병렬 연결하여 구성한다. 스위칭 소자로 싸이리스터를 사용하는 VS 컨버터는 정역 운전모드 변환과정에서 컨버터의 안전운전을 위해 Dead Time 구간을 필요로하며, 이 과정에서 유도성 부하에 영(Zero)전류 불연속 구간이 발생하는 단점이 있다. VS 컨버터의 출력 전류제어에 순환전류를 이용할 경우에는 빠른 정역 운전모드 변환이 가능하며, 부하에 발생하는 영전류 불연속 구간을 제거할 수 있다. 본 논문은 ITER VS 컨버터에서 출력전류의 정역 운전을 위해 순환전류를 이용하는 부하 전류제어 알고리즘을 제안하고, PSIM 시뮬레이션을 통해 결과를 검증하였다.

• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.989-998
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• 2020

Recently, demands for large-capacity electronic loads are increasing in various industries such as a reliability test for the performance of a DC power supply device or a dummy-load for improving the stability of an independent microgrid to be actively built in the future. The electronic load required in these various fields requires an operation such as a continuously variable resistance load while minimizing the switching harmonic component generated in the electric load current in order to reduce the influence of interference from the load peripheral device. Electronic loads require a system that minimizes switching current ripple for load control. Therefore, in this paper, we propose a three-level module converter structure to reduce the current ripple of an electronic load, and a multilevel interleaved power converter topology to reduce the current ripple. The validity of the proposed electronic load, 3-level 6 interleaver converter, was verified by simulation and experiment. In addition, the user's convenience was provided by applying the emotional command curve interface method.

• 한국컴퓨터정보학회논문지
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• 제29권6호
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• pp.143-151
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• 2024

본 논문은 부스트 PFC (Power Factor Correction) 컨버터의 경부하시, 컨버터의 인덕터 전류 왜곡을 수학적으로 분석하고 원인을 정의한다. 경부하시 평균 전류 모드제어에서 인덕터 전류가 불연속적으로 도통하게 되어 부정확한 인덕터 전류 평균값이 전류 제어에 반영된다. 예측 전류 모드제어에서는 인덕터 전류에 비해 전류 리플이 상대적으로 커져 전류 왜곡이 심해진다. 또한 모델 예측 전류제어의 경우 인덕터 전류의 첨두치 부근에서 스위치가 OFF된다. 인덕터 전류 왜곡은 total harmonic distortion 증가와 역률 감소를 유발하기 때문에 반드시 해결되어야 한다. 본 논문은 수학적 분석을 기반으로 부스트 PFC 컨버터의 경부하시 전류 왜곡을 완화할 수 있는 설계 절차를 선정한다. 마지막으로 hardware-in-the-loop simulation을 사용하여 경부하시 제어 방법들을 비교분석했다.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.178-181
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• 2003

Intermediate cooling for current lead is used of thermal link in conduction cooling and cooled of itself in liquid cooling because it is put in liquid. If a existing formula for cooling load and optimal diameter-length of current lead is applied, it generate some more cooling load. Therefore, variation of thermal link height and holding depth in liquid is considered. This result is used of reducing cooling load of current lead occupying most of superconducting system load and applying liquid/conduction cooling systems.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.155-158
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• 2001

In this paper, the Load Current Observer Design for 3-phase Voltage Type PWM Converter with DC Meter Load. The sinusoidal input current and unity input power factor are realised based on the estimated source voltage performed by the Load Current Observer using actual currents and DC link voltage.

• 한국통신학회논문지
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• 제16권4호
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• pp.335-341
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• 1991

구형 혼안테나에 의한 EMI문제를 해결하기 위하여 근거리 영역에 대한 복사 전자계식을 세운다. 전자계 해석 방법과 전송선이론을 적용하여 인접한 전송선 부하에 흐르는 EMI 부하전류를 계산한다. 거리와 주파수 및 송, 수전단 임피던스에 따른 부하전류 전달함수로 부터 EMI의 최소화조건을 찾아낸다. 송전단 임피던스가 작아질수록 EMI 부하전류는 커지고 송전단 임피던스가 커질수록 EMI 부하전류는 작아진다.