• 전력전자학회논문지
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• 제23권3호
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• pp.182-189
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• 2018

LLC resonant converters or phase-shift full-bridge converters have been widely used as DC - DC converters for rapid charging of electric vehicles (EVs). However, these converters present critical disadvantages, including a large circulating current, which can hinder efficiency and miniaturization in EV battery charger applications. In this paper, a new DC - DC converter topology is proposed for EV rapid chargers. The proposed converter can operate at high frequency despite a high rated power capacity of over 20kW, and the problem of circulating current can be minimized during the entire battery charging time. Owing to these advantages, the proposed converter can achieve a high conversion efficiency of over 97% for EV rapid charger applications. The performance of the proposed converter is verified with 20kW prototypes in this study.

• 대한토목학회논문집
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• 제38권6호
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• pp.887-894
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• 2018

전 세계적으로 자동차 시장은 전기차, 수소차와 같은 친환경 차량의 도입이 추진되고 있다. 그러나 내연기관 차량 대비 고가의 차량가격, 제한적인 주행거리 등의 단점은 친환경 차량 확대에 장애요인이 되고 있다. 이에 본 연구에서는 친환경 차량인 전기차 구매에 미치는 영향요인을 분석하기 위해 이항 로지스틱 회귀 모형을 구축하였다. 모형의 종속변수는 구매의사 여부, 독립변수는 사회 경제적 변수와 전기차 구매에 영향을 미치는 특성변수로 설정하였으며, 다중공선성 문제를 해결하기 위해 독립변수 간 상관관계를 분석하여 상관계수가 높은 변수들을 제외하였다. 분석결과, 사회경제적변수인 차량보유대수, 성별, 나이는 유의한 영향을 미치지 않는 것으로 나타났다. 반면, 차량가격에 영향을 미치는 변수와 전기차 충전과 관련된 변수, 전기차 정책 및 시승정보 제공 부족 변수는 전기차 구매에 유의한 영향을 미치는 것으로 나타났다. 이를 통해 향후 전기차 보급과 관련된 정책 입안 시 전기차의 가격 결정과 찾아가는 전기차 충전 서비스 운영 등 충전 불편 해소 방안, 전기차에 대한 정보 제공 및 시승기회 확대 등의 정책을 추진하는 것이 바람직할 것으로 보인다. 본 연구 결과는 지자체 전기차 보급 활성화 및 정책 수립에 도움이 될 것으로 기대된다.

• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.67-71
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• 2015

The concept known as Vehicle-to-Grid (V2G) is to provide power to help balance loads by charging at night when demand is low and sending power to the grid when demand is high. Therefore, it is important to model the cost-benefit characteristics of Electric vehicle(EV)'s operation considering the negawatt market in real time. This paper proposes a methodology to formulate the various costs and economic benefits for sending the EV's power back to the grid, including a concept of inconvenience costs caused by operating the EV as a battery. This paper also introduces the general decision-making process based on the cost-benefit analysis in order to simulate the reasonable participation of V2G service. In the case study, it is confirmed by two-case simulations that the proposed approach is useful to help EV owners' decision-making. In the future, it is expected that the proposed methodology can be used as a decision-making guideline to help prepare the EV' power transmission.

• 한국수소및신에너지학회논문집
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• 제30권4호
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• pp.356-361
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• 2019

Since the government announced the roadmap to revitalize the hydrogen economy, we are constantly making the effort to expand the use of fuel cell electric vehicles (FCEV) and hydrogen charging stations. There is however a significant issue to build and operate the hydrogen charging station due to the lack of the profit model. Many researchers believe that the supply of FCEV will be increased in the near future and finally ensure the economy of hydrogen charging stations. This study shows that the sales changes of hydrogen gas and consumption patterns by the operation of the hydrogen charging station in Changwon City. The results will be used as the evidence to support for operating the hydrogen charging station by private businesses and the validity of additional establishment of hydrogen charging stations.

• 한국초전도ㆍ저온공학회논문지
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• 제20권1호
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• pp.23-27
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• 2018

As the wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air, there are advantages compared with the wired counterparts, such as convenient, safety and fearless transmission of power. From this reason, the WPT systems have started to be applied to the wireless charging for various power applications such as train, underwater ship, electric vehicle. This study aims for the effect and characteristics of different inserted resonance coil between Tx and Rx coils for charging system of superconducting magnetic levitation (MAGLEV) train. The transfer efficiency and effect are evaluated with helix type, rectangular type copper resonance coil, and HTS resonance coil under bulb and HTS magnet load, respectively. The input power is adapted with radio frequency (RF) power of 370 kHz below 500 W.

• 한국정보전자통신기술학회논문지
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• 제14권1호
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• pp.91-97
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• 2021

전기자동차를 이용하여 계통에 전력을 공급하는 Vehicle to Grid(V2G)의 구현을 위한 통신표준으로 ISO/IEC 15118이 적용되고 있다. 통신 프로토콜에 기반을 두는 전기자동차의 충방전 제어 시에 필연적으로 충방전 실행까지의 시간지연이 발생하게 되는데, 이러한 시간지연은 전력 유연성 공급 측면에서 제한의 요인이 된다. 본 연구에서는 ISO/IEC 15118 기반 V2G 에뮬레이터를 구현하고 전기 자동차 충방전 제어에 따른 반응성을 확인하였다. 실험결과 시간지연은 0.12ms로 나타났으며, 이를 기반으로 현 표준 하에서 참여 가능한 전력 유연성 시장에 대하여 검토하였다.

• 전기학회논문지
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• 제65권2호
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• pp.264-268
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• 2016

Recently, various energy efficiency optimization activities are ongoing globally by integrating conventional grids with ICT (Information and Communication Technology). In this sense, various smart grid projects, which power suppliers and consumers exchange useful informations bilaterally in real time, have been being carried out. The electric vehicle diffusion program is one of the projects and it has been spotlighted because it could resolve green gas problem, fuel economy and tightening environmental regulations. In this paper, the economics of V2G system which consists of electric vehicles and the charging infrastructure is evaluated comparing electric vehicles for V2G with common electric vehicles. Additional benefits of V2G are analyzed in the viewpoint of load leveling, frequency regulation and operation reserve. To find this benefit, electricity sales is modeled mathematically considering depth of discharge, maximum capacity reduction, etc. Benefit and cost analysis methods with the modeling are proposed to decide whether the introduction of V2G systems. Additionally, the methods will contribute to derive the future production and the unit cost of electric vehicle and battery and to get the technical and economic analysis.

• 전력전자학회논문지
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• 제20권5호
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• pp.479-490
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• 2015

The conventional phase-shifted full-bridge (PSFB) converter with an LC filter has been widely used for high-power applications of over 1.0 kW. However, the PSFB converter cannot obtain optimal power conversion efficiency during the battery charging in electric vehicle (EV) on-board battery charger applications because of its unique drawbacks, such as a large circulating current and very high voltage stress in the rectifier diodes. As a result, the converters with a capacitive filter, such as LLC resonant converters, replace the PSFB converter in the EV chargers. This study analyzes the problems of the PSFB converter for EV on-board charger applications in detail. Moreover, the newest converters based on the conventional PSFB converter are reviewed. On the basis of the reviews, new PSFB converter topologies are proposed for EV charger applications. The new topologies are formed by connecting the rectifier stage in the PSFB converter with the output of an LLC resonant converter in series. Many problems of the conventional PSFB converter for EV charger applications can be solved and the performance can be more improved because of this structure; this idea is confirmed by an experiment consisting of prototype battery chargers under the output voltage range of 250-450 Vdc at 3.3 kW.

• 한국융합학회논문지
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• 제5권3호
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• pp.23-27
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• 2014

최근에 스마트폰과 디바이스의 무선충전에 대한 관심이 높아지고 있으며, 많은 기업들이 무선충전을 개발하고 있다. 무선충전은 앞으로 모바일기기뿐만 아니라 노트북 청소기 등 거의 모든 전자제품으로 적용 범위가 확대될 것이다. 무선충전 전기자동차도 올해 본격적으로 선을 보일 예정이다. 이렇듯 무선충전은 연관시장이 무궁무진하다. 세계 10대 유망기술에 포함되어 있는 무선충전은 매년 100% 이상 급성장할 전망이라고 한다. 하지만 그에 따라 존재하는 기술적 한계점과 인체 유해성에 대한 보안위협을 분석해 안전한 환경에서 사용할 수 있도록 해야 하고 각종 제도적 보안도 마련해야 한다. 무선충전에 대한 표준화와 보안대책요구사항은 체계적이지 않다. 본 논문은 모바일기기에서 자기공진방식의 무선충전의 보안 위협과 보안요구사항을 정의해 분석하고자 한다.

• 산업경영시스템학회지
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• 제41권4호
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• pp.9-21
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• 2018

In South Korea, Jeju Island has a role as a test bed for electric vehicles (EVs). All conventional cars on the island are supposed to be replaced with EVs by 2030. Accordingly, how to effectively set up EV charging stations (EVCSs) that can charge EVs is an urgent research issue. In this paper, we present a case study on planning the locations of EVCS for Jeju Island, South Korea. The objective is to determine where EVCSs to be installed so as to balance the load of EVCSs while satisfying demands. For a public service with EVCSs by some government or non-profit organization, load balancing between EVCS locations may be one of major measures to evaluate or publicize the associated service network. Nevertheless, this measure has not been receiving much attention in the related literature. Thus, we consider the measure as a constraint and an objective in a mixed integer programming model. The model also considers the maximum allowed distance that drivers would detour to recharge their EV instead of using the shortest path to their destination. To solve the problem effectively, we develop a heuristic algorithm. With the proposed heuristic algorithm, a variety of numerical analysis is conducted to identify effects of the maximum allowed detour distance and the tightness of budget for installing EVCSs. From the analysis, we discuss the effects and draw practical implications.