• 전력전자학회논문지
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• 제25권5호
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• pp.333-342
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• 2020

Power exchanges between the grid and the battery through a bidirectional DC-DC converter are essential for DC microgrid systems. In general, the battery is charged when the grid is connected, and the system is powered by the battery when the grid is disconnected. In this mode transition, the saturation of the voltage controller slows down output response and produces large transient errors in DC link voltage. To solve this problem, a novel anti-windup design is proposed to improve anti-windup performance further. The proposed method stabilizes DC bus voltage through a wider range of battery voltage with faster transition compared with that of conventional methods. The proposed method is verified through an experimental setup composed of a 125 W laboratory-scale DC microgrid system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.126-131
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• 2001

This paper deals with implementation of inverter systems for DC power regeneration, which can regenerate the excessive DC power from DC bus line to AC supply in substations for traction systems. From the viewpoint of both power capacity and switching losses, a three-phase square-wave inverter system is adopted. To control the regenerated power, the magnitude and phase of fundamental output voltages should be appropriately controlled in spite of the variation of input DC voltage. Inverters are operated with modified a-conduction mode to fix the potential of each arm. The overall system consists of the line-to-line voltage and line current sensors, an actual power calculator using d-q transformation method, a complex power controller with PI control scheme, a gating signal generator for modified $\alpha-conduction\;mode\;with\;\delta\;and\;\alpha$, a DPLL for frequency followup, and power circuit.

• 한국통신학회논문지
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• 제32권3A호
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• pp.319-323
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• 2007

본 논문에서는 50-1000 MHz의 주파수 범위에서 전력과 임피던스의 표준을 이용하여 RF전압을 자동으로 정밀 측정을 하였다. RF-DC차를 결정하기 위하여 동축형 미소열량계와 자동 회로망 분석기가 이용되었으며, 총불확도는 약 1 % 이다. 써미스터 마운트의 실효효율과 열전압 변환기의 RF-DC차를 측정하기 위하여 HP 컴퓨터와 Commodore 컴퓨터, 그리고 IEEE-488 인터페이스 버스를 이용하고, 측정하는 전체과정이 자체 개발한 프로그램에 의해 자동으로 수행되었다.

• 전력전자학회논문지
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• 제25권2호
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• pp.103-110
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• 2020

In this study, the design and operating strategy of DC home grid with PV, battery, and ultracapacitor have been discussed, The proposed sizing method can find the optimum size of the battery and PV which can reduce yearly utility energy consumption, whereas the control scheme can maintain the DC-bus voltage level of the DC home grid under different operating conditions, where day or night time operation, load and PV power levels, and the maximum current and state-of-charge of batter are considered. In addition, a supervisory power management strategy has been suggested, and its validity has been verified by HILS (hardware in-the-loop simulation) results.

• Journal of Power Electronics
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• 제17권4호
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• pp.1071-1087
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• 2017

This paper introduces a DC/AC converter, which can be connected in parallel with a diode rectifier for regenerative applications. The DC/AC converter is supposed to transmit regenerative energy to the power grid when a motor is braking. Isolation transformers are not needed in the topology, which can reduce the size and cost. An analysis of the zero-order current existing in the system is carried out. In addition, algorithms to minimize the zero-order current, control the power factor and keep the DC bus voltage stable are discussed. A 55kW industrial prototype is built to verify the proposed analysis and control strategies.

• 전력전자학회논문지
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• 제24권3호
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• pp.191-200
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• 2019

This study proposes a hardware-in-the-loop simulation (HILS) system based on National Instruments' PXI platform to test power management and operation strategies for DC microgrids (MGs). The HILS system is developed based on the controller HIL prototype, which involves testing the controller board in hardware with a real-time simulation model of the plant in a real-time digital simulator. The system provides an economical and effective testing function for research on MG systems. The decentralized power management strategy based on the DC bus signaling method for DC MGs has been developed and implemented on the HILS platform. HILS results are determined to be similar to those of the off-line simulation in PSIM software.

• 대한교통학회지
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• 제23권2호
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• pp.151-160
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• 2005

버스와 같은 대중교통의 경우에는 서비스수준을 평가하는 효과철도에 확률의 개념이 사용되어, 확률값의 선형비례적인 수치를 기준으로 A~F의 서비스수준의 등급을 구분하기도 한다.(TCQSM: Transit Capacity and Quality of Service Manual-2nd Edition, TRB, Washington DC., 2003) 이 경우 운전자나 승객이 느끼는 정도와 확률값이 선형비례 관계에 있지 않을 수 있는데 이는 서비스수준을 적절하게 반영한다고 볼 수 있다. 본 연구에서는 TCQSM에서 제시하고 있는 버스 운행의 정시성 평가 사례를 통해 확률값의 선형비례적인 수치를 기준으로 서비스수준의 등급을 구분할 때 발생하는 문제점을 분석하고, 이러한 문제점을 보완하는 적절한 서비스수준 기준을 산정하는 방법론을 제시하였다. 본 연구에서 제시한 차두간격 분산계수 분포의 확률밀도를 기준으로 서비스수준의 기준을 산정하는 방법은 승객의 평균 대기시간을 적절하게 반영하고, 실제 버스 운행 자료를 사용하여 적용한 결과, TCQSM에서 제시한 방법보다 더 적절하게 버스의 운행 신뢰성을 평가하는 것으로 나타났다. 그러나 효용함수를 이용하여 서비스수준의 기준을 산정하는 방법은 이용자가 느끼는 서비스수준과 효용차이의 관계에 대한 추가적인 연구가 필요한 것으로 본 연구의 한계로 남는다.

• Journal of Power Electronics
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• 제18권5호
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• pp.1303-1314
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• 2018

To match the dynamic lower voltage of a fuel cell stack and the required constant higher voltage (400V) of a DC bus, an H-type structural Boost three-level DC-DC converter with a wide voltage-gain range (HS-BTL) is presented in this paper. When compared with the traditional flying-capacitor Boost three-level DC-DC converter, the proposed converter can obtain a higher voltage-gain and does not require a complicate control for the flying-capacitor voltage balance. Moreover, the proposed converter, which can draw a continuous and low-rippled current from an input source, has the advantages of a wide voltage-gain range and low voltage stress for power semiconductors. The operating principle, parameters design and a comparison with other converters are presented and analyzed. Experimental results are also given to verify the aforementioned characteristics and theoretical analysis. The proposed converter is suitable for application of fuel cell systems.

• 대한전기학회논문지:전력기술부문A
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• 제55권8호
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• pp.334-340
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• 2006

Copper is widely used in electric wire, cable, conductor in electric devices. As the demand for electric power is increasing rapidly, electric power devices are getting amazingly bigger and complicated. The using of light-weight conductor can reduce the size and making cost of the electric devices. In high-frequency application, Electric current in a conductor tends to shift to the surface of the conductor, resulting in an uneven current distribution in the inner conductor. In the extreme case the current may essentially concentrate in the 'skin' of the inner conductor as a surface current. In high frequency application, therefore, inner area of copper conductor may replace with aluminum conductor, which reduces the weight of conductor. This paper describes the manufacture and evaluation of composite conductors made of copper and aluminum. The optimum extruding ratio was 16 at $300^{\circ}C$. The electrical resistance of manufactured composite bus bar was $57{\mu}{\Omega}$ at DC and $49.5{\mu}\{Omega}$ at 300Hz.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2000년도 봄 학술발표논문집 Vol.27 No.1 (A)
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• pp.45-47
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• 2000

본 연구는 심볼릭 모델 체커 중의 하나인 SMV(Symbolic Model Verifier)를 이용하여 한국전자통신연구원(ETRI)에서 개발한 CCA(Cache Coherent Agent) 보드를 위한 I-Link Bus(Inside Bus)의 몇 가지 특성(property)들을 검증하여 I-Link Bus의 요구사항(requirement)이 만족됨을 보인다. 이 검증에서는 I-Link Bus의 모델을 SMV 입력 언어로 명세하며, 검증할 특성들을 시제 논리(temporal logic)를 이용하여 나타낸다. 검증을 통해서 I-Link Bus와 PIF(Processor Interface), DC(Directory Controller), RC(Remote access cache Controller)모듈들이 중재기 우선 순위, send 우선 순위, 중재 요청 신호의 관리, liveness등의 특성들을 만족한다라는 것을 검증하였다.