역률 개선용 칩을 사용한 플라이백 방식의 능동역률 보정기

정영국 대불대학교 1998 論文集 Vol.4 No.1

In this paper, Implementation of flyback type active power factor corrector using a power factor control chip has been proposed. The ML4813 chip made by Micro-linear is used to implement a discontinuous mode flyback power factor regulator for power factor improvement and harmonic reduction. It is the only controller that is optimized for control of a discontinuous flyback type active power factor corrector with low cost and low power voltage control mode. PWM duty ratio of controller is constant at any given line and load condition and over voltage/over current comparator inside controller is used to protect switching device. To verify the validity of the proposed system, the experiment has been achieved in detail under steady state conditions. With the proposed flyback circuit, near unit power factor and harmonic reduction of dc power supplies for power electronics applications are easily achievable with a minimum of external components.

DSP를 사용한 능동전력필터 시스템 개발

정영국 대불대학교 1996 論文集 Vol.2 No.2

This paper proposes a novel system of DSP based active power filter with real-time power analyzing/compensating function. A developed system is made up of 486-PC and DSP(digital signal processor) board, IGBT power module, nonlinear load, and power analyzing and control program for windows. Power is analyzed using signal processing techniques based on the correlation between voltage and current waveforms. Since power analysis algorithm is performed by DSP. power analysis is achieved in real-time even under highly dynamic nonlinear loading conditions. Combining control algorithm with power analysis algorithm, flexibility of a developed system which has both power analysis mode and control mode, is greatly inhenced. To verify the validity of a developed system, the experimental system of a 1KVA maximum power rating is used for compensating nonactive (reactive and distorted) current generating while thyristor speed controller of induction motor is operating. From experimental results, it is clear that under highly distorted, dynamically changing current conditions, the compensation system and controller are capable of compensating nonlinear load to a nearly unity power factor, with nonactive current compensation. Also, various graphic screens of time domain/frequency domain/ 3-D current coordinates are displayed with experimental results on 486-PC by a developed system. Finally, because power analysis capability of the proposed system is excellent, it is expected that the proposed system can be applied to DSP based power analyzer as well as high power reactive power compensator.

비선형 부하의 전류 동기 검출 기법

정영국,김영철 대불대학교 2001 論文集 Vol.7 No.1

Active current components in each phase of nonlinear load in serious unbalanced power condition, are symmetrically and equally detected by current synchronous detection(CSD) theory. But, in case of case of distorted conditions in power system, the CSD theory is not suitable any more, since the information of current components can be easily corrupted by the distorted utility voltage such as harmonics in waveform. Therefore, a new algorithm, the CSD theory by detecting positive sequence detection(PSD) of utility, is proposed in this paper. The proposed CSD theory is experimented and tested under distorted as well as asymmetrical condition in power system.

2상 랜덤 펄스 중앙 배치 PWM을 기반으로 한 3상 모터 구동 시스템의 파워 스펙트럼

정영국 대불대학교 2003 大佛大學校大學院 硏究論文集 Vol.2 No.1

The objective of this paper is to investingate the power spectrum of a two-phase RCD(Random Pulse Centered Displacement)PWM scheme where the two-phase pulses are mutually center-aligned as in SVM(Space Vector Modulation). But the common pulse center is displaced randomly from the middle of the period. To verify the validity of the proposed scheme, the power spectra of the output voltage, the ripple current, the d.c link current in the inverter drives and the radiated acoustic noise are experimentally investigated. And, the performance of the proposed scheme was compared and discussed with the conventional schemes.

단위법(P.U)에 의한 AC/DC 다이오드 정류기의 입력LC필터 설계

정영국 대불대학교 1997 論文集 Vol.3 No.1

The goal of this paper is input LC filter design of AC/DC diode rectifiers by Per Unit Basis. It consisted of an input LC parallel resonent tank whose inductor and capacitor values are selected so that the input filter presents an infinite impedance to harmonic input ac current component. The operation of proposed input filter has been analyzed in detail under steady state conditions. Performance evaluation and related design data have been provided on Per Unit for the proper implementation of diode rectification system. Finally, Detailed input and output current analysis has shown that the proposed input filter yield high quality input ac current waveforms, in particular, high input power factor values and more reliability which reducing the VA rating of passive components as compared to the standard type LC filter.

중성선 전류 및 고조파류 저감을 위한 공간벡터 검출법 기반의 3상 4선식 능동전력필터

정영국,김영철 대불대학교 2004 大佛大學校大學院 硏究論文集 Vol.3 No.-

This paper deals with a space vector detection based a 3-phase 4-wire 4-leg active power filter which is proposed for reduction harmonic and neutral current in a 3-phase 4-wire supply system. The harmonics are cal-culated by the space vector detection and the neutral current is calculated from load current. The proposed system separately compensates harmonic and neutral current. For the investigation of a desired performance, the de-veloped algorithm is simulated using a PSIM. And steady state as well as transient state results are given and discussed in detail.

가상 전력 이론에 대한 Comments와 실험적인 검증

정영국 대불대학교 2003 論文集 Vol.9 No.1

This paper presents comments and experimental verification on the fictitious power theory suggested by Van Wyk and Enslin. The power in the theory is defind and analyzed by time domain approach, thus it is easy to understand and instrument. The power is decomposed into active, reactive and deactive components based on the autocorrelation and crosscorrelation signal techniques between voltage and currentwaveforms. On the compensation property, active power filter deal with three components only. Also, for real time control of active power filter, the power models with difficultconcept are not cost effective. For the verification of the fictitios power theory, experimental work for DSP(digital signal processor) based voltage type active power filter is achieved. The power of thyristor controlled motor drive system is decomposed into three orthogonal components by the fictitious power theory.

불평형 전원하의 능동전력필터를 위한 순시보상 알고리즘

정영국 대불대학교 2000 論文集 Vol.6 No.1

This paper describes a new algorithm for active power filters which can be control source current symmetrically under unbalanced condition in power system. Positive sequence voltage is detected by symmetrical coordinate method, and compensating reference current of active power filters is calculated using by accurate phase angle information of positive sequence voltage. The basic principle of the proposed method is described in detail, and the conventional and proposed phase detecting methods are compared and discussed through the simulation results.

Nutritional Impacts on Fast Food Selection in Children

박정옥,장정옥,김영국 동국대학교 관광산업연구소 1999 관광·호텔경영연구 Vol.1 No.1

소비자들이 건강과 영양에 대한 관심이 점점 커져가고 있다. 특히 패스트푸드 경영에서 아동들이 영양에 대한 관심은 매우 중요하다. 따라서 본 연구는 우리 나라 아동들이 영양에 대한 관심과 그것이 메뉴선택에 미치는 요인들을 분석하여 향후 외식업의 대처방안을 제시하고 있다.

통신망을 활용한 프로젝트 학습 모형의 개발 및 적용과 메시지 분석을 이용한 상황적 평가

전영국,김정학,박홍준 한국컴퓨터교육학회 2005 컴퓨터교육학회 논문지 Vol.8 No.4