• 대한전기학회논문지
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• 제45권1호
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• pp.30-41
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• 1996

Current Source(CS) PWM converter is appropriate for the magnet power supply system which requests high power and high precision current control. Input and output filters should be installed to eliminate the current or voltage harmonics caused by the PWM switching for the CS PWM converter. But the input/output filters limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicated. In this paper, systematic and simple filter design method which considers not only the harmonic attenuation but also the total system good transfer function characteristics in the dc filter. The simulated and experimental results verify the proposed theory. (author). refs., figs., tabs.

• 한국컴퓨터정보학회논문지
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• 제23권12호
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• pp.179-184
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• 2018

In this paper, we have proposed the development of DC-DC converter for LRT power supply. First of all, we have studied converter technology, main functions and characteristics were determined. In also, the converter design was carried out to meet the system design conditions. Based on this design, converter simulation is performed to enable stable charging and discharging of the vehicle system. We have performed the Light-load test according to charge mode, discharge mode. As a result, the manufactured converter performance was verified through the load test, and it's stability was confirmed.

• 대한전기학회논문지:전력기술부문A
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• 제54권9호
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• pp.427-433
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• 2005

In DC tracking power supply system, ground faults are currently detected by the potential relay, 64P. Though 64P relay detects ground fault, it cannot Identify the faulted region which causes long traffic delays and safety problem to passengers. Two new ground fault protective relay schemes that can identify the faulted region are presented in this paper. One is bus differential protective relay and the other is ground overcurrent protective relay. Both type of relays is similar in principle to the ordinary bus differential protective relay and the ground overcurrent relay used in other power system. In DC traction power supply system, since it is ungrounded, ground fault current is not big enough to operate those relays. To solve the problem, a current control device, called device 'X', is newly introduced in both system, which enables large amount of ground fault current flow upon the positive line to ground fault. Algorithms for these relays are developed and their validity are verified by EMTP simulation.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1967-1977
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• 2014

In this paper, for the development of a safe and reliable DC home appliance suitable for DC home power supply system, we classified a number of inherent problems with help of the comparative analysis of existing AC and new DC home appliance. Several new technical problems of DC home appliances are mainly linked to the DC transient state. Among them, this paper concentrates on start-up inrush current problem, uni-polarity problem, and heavy DC load control problem. And to address these problems, we herein present an implementation of robust safety circuits for DC home appliances. Specifically, we investigate several multi-circuit countermeasures and select the best among them through comparative evaluation, based on theoretical, simulational, and experimental results.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권7호
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• pp.430-436
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• 2004

This paper presents an advanced control technique for power density maximization of the Brushless DC (BLDC) generator by using the linear tracking method. In a generator of given rating, the weight and size of the system affect the fuel consumption directly. Therefore, power density is one of the most important issues in a stand-alone generator. BLDC generator has high power density in the machine point of view and additional increases of power density by control means can be expected. Conventional rectification methods cannot achieve the maximum power possible because of hon-optimal current waveforms. The optimal current waveform to maximize power density and minimize machine size and weight in a nonsinusoidal power supply system has been derived, incorporated in a control system, and verified by simulation and experimental work. A new simple algebraic method has been proposed to accomplish the proposed control without an FFT which is time consuming and complicated.

• 조명전기설비학회논문지
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• 제24권6호
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• pp.160-168
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• 2010

본 논문은 직류전기철도 급전시스템에서 누설전류와 변전소로부터 공급되는 전류의 분포에 대하여 다루었다. 일반적으로 직류전기철도 급전시스템에서는 운행용 레일을 귀로 전류(부극성)의 도체로 사용하고 있으며, 이러한 조건은 추가적인 도체의 설치를 필요로 하지 않기 때문에 경제성을 고려한 것이다. 그러나 운행용 레일과 대지 사이의 저항이 작은 경우에는 대지로 흐르는 누설전류가 문제가 된다. 이 누설전류는 레일 주변에 설치된 지하 매설물에 영향을 미치며, 인체의 안전과도 관련이 있다. 따라서 직류전기철도 급전시스템에서 누설전류를 억제하는 것은 차량의 운전이나 안전 측면에서 중요한 문제이다. 본 논문에서는 직류전기철도 급전시스템에 대하여 CDEGS의 SPLIT 프로그램을 이용하여 레일의 전류분포를 시뮬레이션하였고, 레일의 누설저항 크기에 따른 누설전류 변동치를 도출하였다.

• Journal of Power Electronics
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• 제17권2호
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• pp.490-500
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• 2017

Fuel cell (FC) is a promising power supply in electric vehicles (EV); however, it has poor dynamic performance and short service life. To address these shortcomings, a super capacitor (SC) is adopted as an auxiliary power supply. In this study, the frequency decoupling control method is used in electric vehicle energy system. High-frequency and low-frequency demand power is provided by SC and FC, respectively, which makes full use of two power supplies. Simultaneously, the energy system still has rapidity and reliability. The distributed power system (DPS) of EV requires DC-DC converters to achieve the desired voltage. The stability of cascaded converters must be assessed. Impedance-based methods are effective in the stability analysis of DPS. In this study, closed-loop impedances of interleaved half-bridge DC-DC converter and phase-shifted full-bridge DC-DC converter based on the frequency decoupling control method are derived. The closed-loop impedance of an inverter for permanent magnet synchronous motor based on space vector modulation control method is also derived. An improved Middlebrook criterion is used to assess and adjust the stability of the energy system. A theoretical analysis and simulation test are provided to demonstrate the feasibility of the energy management system and the control method.

• 전기학회논문지
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• 제65권11호
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• pp.1913-1918
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• 2016

In order to analyze the power consumption pattern of the DC urban rail system, the method to obtain a solution establishing the current equation according to fixed position of the substation and varying position of the train is used. The proposed analysis method using the network analysis is to model the transfer function of the component constituting a direct current power supply system (dc substation, train, catenary) to the voltage and current. By multiplying the model formula consecutive, it can calculate the voltage and current of each element of power supply circuit and shows a simple case analysis.

• 한국에너지공학회:학술대회논문집
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• 한국태양에너지학회, 한국에너지공학회 1993년도 춘계 공동학술발표회 초록집
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• pp.47-52
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• 1993

Recently, as exactly clean source, the research of photovoltaic power generation is undertaken actively and widely. In this paper, an auxiliary power supply system which is composed of photovoltaic generation and DC-DC boost chopper is described. This system in mainly for Air-conditioner appliances is which AC source is formed through rectifying circuit and without electrical storage battery. There exist two operating modes depending on the power quantity of the solar cells and the load. The control algorithm is discussed.

• 조명전기설비학회논문지
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• 제20권4호
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• pp.86-97
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• 2006

전기철도 급전시스템의 설계와 평가에 관련하여 어려운 점은 고려해야 할 요소들이 많고, 시스템적 접근이 요구되나 단편적인 논문과 엔지니어링 측면의 접근이 대부분이다. 본 논문에서는 전기철도 시스템 중 국내외에서 최근 활발히 추진되고 있는 경량전철을 위한 직류 급전시스템의 설계 및 그의 적정성을 평가하는 기법을 체계화하였다. 먼저, 급전 시스템의 구성요소인 급전 변전소와 부하인 차량과 그리고 전력선을 포함한 전체 시스템의 특성파악하고 분석하였다. 실제 계통과 동일하게 모델링하기 위하여 축약 및 등가화를 하였으며, 등가화한 시스템을 해석하기 위한 방안으로 노드방정식과 반복접근법을 적용하였으며, 이를 체계화하여 모의절차, 평가 및 설계방법을 제시하였다. 제시한 알고리즘 및 설계절차에 따라 프로그램을 개발하였으며 사례연구를 통하여 그 유효성을 입증하였다.