다수 및 소수캐리어 소자에 적용 가능한 영전압영전류 스위칭 컨버터

안희욱,김학성,Ahn Hee-Wook,Kim Hack-Sung 전력전자학회 2005 전력전자학회 논문지 Vol.10 No.5

제안된 회로는 하나의 보조스위치를 이용하여 주 스위치와 정류용 다이오드가 턴-온/턴-오프 시 동시에 영전압과 영전류 조건을 만족시킨다. 그리고 이 회로에 사용되는 주 스위치는 다수 캐리어 소자뿐만 아니라 소수 캐리어 반도체 소자까지 사용할 수 있는 장점을 가지고 모든 PWM 컨버터에 적용 가능하다. 그리고 제안된 보조 스위치와 공진회로가 주 전력 경로에 존재하지 않으므로 주 스위치와 다이오드에 더 이상의 전압/전류 스트레스가 없게 된다. 제안된 컨버터의 유효성을 이론적 분석과 실험을 통하여 입증하였다. The paper proposes a novel ZVZCS PWM converter. It enables the main switch to be turned on/off with both zero voltage and zero current, the auxiliary switch to be turned on/off with ZCS, the rectifier diode to be turned on/off with ZVS. Moreover, this proposed soft switching technique is suitable for not only minority carrier device but also majority carrier semiconductor device. Since auxiliary resonant circuit of the proposed boost converter is placed out of the main power path, therefore, there are no voltage and current stresses on the main switch and diode. The operation of the proposed boost converter is explained and analyzed theoretical and experimentally, from a prototype operating at 100KHz.

태양광 PV 스트링에서의 모듈 부정합 손실의 분석 및 개선 기법 타당성 연구

안희욱(Ahn Hee-Wook) 한국태양에너지학회 2009 한국태양에너지학회 논문집 Vol.29 No.1

In this paper, the power loss due to PV module mismatch in PV string is analyzed and a mismatch compensation method is proposed to improve the efficiency of PV system. The analysis of mismatch loss using PV model simulation reveals that the mismatch module may decrease the total efficiency because the MPPT function of power conditioner make the PV system operate at the local maximum point. The mismatch loss can be severe if the maximum power point current of mismatch module is less than that of string. The proposed compensation method which is simply implemented with a buck type conveter shows the possibility to remove the mismatch loss. The effectiveness of the analysis and compensation method is verified by a prototype experiment.

직렬공진출력단을 가진 벅형컨버터를 위한 새로운 제어기설계방법

安熙旭(Hee-Wook Ahn),高政鎬(Jung-Ho Ko),尹明重(Myung-Joong Youn) 대한전기학회 1991 전기학회논문지 Vol.40 No.10

태양광 모듈의 전압 및 전류 파형을 이용한 부정합 진단 기법

안희욱(Ahn Hee-Wook),박기엽(Park Gi-Yob) 한국태양에너지학회 2011 한국태양에너지학회 논문집 Vol.31 No.3

Techniques for mismatch loss minimization to increase the PV system efficiency are under development recently. In this paper, a method to make diagnosis of PV module mismatch is presented, which uses a concept of operating point factor. The method is based on the fact that the ratio of the incremental conductance of a PV module to instantaneous conductance is 1 when the module is operating at its maximum power point. The variations of module voltage and current are taking place by the maximum power point tracker in the power conditioning units of PV system. The effectiveness of the method is verified through an application to a real PV system.

태양광 시스템의 부정합 손실 저감을 위한 모듈 전류 보상 기법

안희욱(Ahn Hee-Wook),박기엽(Park Gi-Yob) 한국태양에너지학회 2012 한국태양에너지학회 논문집 Vol.32 No.3

A current compensation method to reduce the mismatch loss in PV systems is proposed as a way to increase the power generation efficiency. A de-de converter is used to supply currents to irregular modules in a PV string and is powered from the string output. The converter's voltage conversion ratio is adjusted so that all the modules in the string arc operated at the maximum power point. The power rating and size of the converter can be reduced since only the current difference between the regular and irregular module may be supplied. The compensated string shows very little voltage mismatch compared to other regular strings. The validity of the proposed method is verified through a simulation and experiments in a prototype PV system.

공진형 고주파 인버터에서의 공진주파수 추적을 위한 PLL 기법

안희욱(Hee-Wook Ahn),김학성(Hack-Sung Kim),김상희(Sang-Hee Kim) 전력전자학회 2000 전력전자학술대회 논문집 Vol.2000 No.11

The PLL (Phase-Locked Loop) techniques are employed to make the switching frequency of a resonant inverter follow the resonant frequency which may vary due to the load variations during operation, The conventional design guide of PLL is not suitable in these case since the inverter characteristics are not considered, In this paper, the phase characteristics of a resonant inverter is analysed and added to the closed loop, And the design of PLL with digital phase detector is illustrated for the output frequency to track the resonant frequency of the inverter.

선형 광결합 절연 증폭기의 주파수 특성분석 기법

安熙旭(Hee-Wook Ahn),成永輝(Young-Whee Sung),金相熙(San-Hee Kim) 대한전기학회 2007 전기학회논문지 Vol.56 No.12

Optically coupled linear isolation amplifier requires special care to avoid oscillation in actual applications. In this paper methods to analyze the frequency characteristics of the amplifier are proposed to reveal the cause of oscillation and to provide design guidelines. The loop gain of the amplifier obtained through the equivalent circuit model shows that the phase margin is too small to ensure stable operations. Methods to get non-oscillatory response are proposed and the resulting frequency responses are analyzed. The common method adding a small capacitor to the amplifier is shown to degrade the frequency bandwidth. The frequency response of output voltage explains the need of filter capacitor in output stage. The usefulness of the method is verified through experiments.

중앙은행 커뮤니케이션이 경제주체의 기대형성에 미치는 영향: 한국은행의 GDP 전망공표를 중심으로

김인배 ( Inbae Kim ),안희욱 ( Hee Wook Ahn ) 한국국제경제학회 2015 국제경제연구 Vol.21 No.3

본고는 한국은행의 커뮤니케이션 수단인 경제전망 공표, 그 중에서도 성장률 전망공표가 전문가들의 성장률전망치 분포(표준편차)에 어떻게 영향을 미치는지 살펴보았다. 1995년 1월부터 2013년 12월까지 Consensus Economics의 전문가 서베이 월별 자료를 이용하여 실증분석한 결과는 다음과 같다. 첫째, 한국은행은 1998년 물가안정목표제 도입 이래 대외 커뮤니케이션이 지속적으로 개선되어왔다고 주장하지만, 적어도 성장률 전망공표의 효과로써 판단할 때, 정작경제주체의 성장률 기대에 영향을 주기 시작한 것은 2004년 중기 물가안정목표제가 시행되면서 부터이다. 둘째, 한국은행의 ‘성장률 공표’는 그 자체로서 독립적으로 경제주체의 기대형성에 영향을 미칠 정도는 아니었다. 대신 그 효과는 한국은행의 전망 예측력에 의존하여, 예측력이 높을수록 경제주체의 기대형성에 미치는 영향력이 더 커짐을 발견하였다. 이러한 효과는 역시 중기 물가안정목표제가 시행되면서 뚜렷해진다. 셋째, 한국은행의 성장률전망 예측력은 한국은행에 대한 신뢰도를 높여 경제주체의 기대형성에 영향을 주는 것으로 보인다. 본고는 한국은행이 물가안정목표제 하에서 커뮤니케이션의 횟수와 양은 증가해 왔지만, 그 효과 면에서는 전망 예측력과 같은 질적 측면이 관건이라는 점을 시사한다. This article investigated how ‘economic forecasting announcement’, the Bank of Korea (BOK)’s representative method of communication, affects the distribution of experts’ GDP growth expectation (standard deviation). Empirical results using monthly professional survey of Consensus Economics from January 1995 to December 2013 are as follows. First, although the BOK asserts that the communication has been constantly improving since the introduction of inflation targeting in 1998, economic agents’ expectation, based on our results, has been influenced only with the introduction of medium-term inflation targeting in 2004. Second, the BOK’s ‘GDP forecasting announcement’ itself had not been independently effective on economic agents’ expectation. Instead, the effect depended on the BOK’s forecasting capability. It has been found that the better the capability, the more influence it had on expectation formation. This trend also strengthened since the introduction of medium-term inflation targeting. Third, the BOK’s forecasting capability seemed to affect economic agents’ expectation through increasing credibility on the BOK. The findings suggest that although the BOK has been increasing the frequency and amount of communication since the inflation targeting, qualitative aspect such as forecasting capability is more crucial than quantitative measures.

PV 스트링의 모듈 부정합 보상용 컨버터

박기엽(Gi-Yob Park),안희욱(Hee-Wook Ahn) 전력전자학회 2009 전력전자학술대회 논문집 Vol.2009 No.2

Mismatch of electrical characteristics of modules in PV string invokes mismatch power loss. The mismatch occurs due to various causes such as shadow, aging, contamination, and module exchange. The concept of mismatch compensation converter(MCC) is presented in this paper to remedy the mismatch loss problem. MCC is connected to irregular modules only. MCC is composed of dc-dc converter and MPPT controller. It is noted that MPPT algorithm is employed to control MCC and is effective for maximum power available from irregular modules. The selection guide of MPPT control period is given based on the period of MPPT in PCU. The effectiveness of the MCC is verified by a prototype experiment.

태양광 PV 어레이에서 병렬 부정합을 저감시키는 모듈 부정합 보상기법

박기엽(Gi-Yob Park),안희욱(Hee-Wook Ahn) 전력전자학회 2010 전력전자학술대회 논문집 Vol.2010 No.7

The power loss due to PV module mismatch in PV array system is analyzed and a mismatch compensation method is proposed. A dc-dc converter is used to compensate for series mismatch caused by a low current module in a string. The converter is controlled to maximize the array power output. The proposed compensation method was verified by PSpice simulation.