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2상 및 3상 변조된 각상별 랜덤 펄스위치 펄스폭 변조기법의 성능비교
위석오(Seog-Oh Wi),임영철(Yung-Cheol Lim),정영국(Young-Gook Jung),나석환(Seok-Hwan Na) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
In this paper, a comparative study on the performance of two-phase and three-phase randonuzed pulse position PWM scheme for mitigation of audible switching acoustic noise in motor drives is done in the randomized pulse position PWM, each of two-phase or three-phase PWM pulses is located randomly in each switching interval. Simulation and experimental efforts were executed to investigate the spread effects of power spectra of inverter output voltage, waveforms of ripple current and audible switching acoustic noise.
2상 SRPP-PWM 기법을 사용한 유도모터 속도제어 시스템
위석오(Seog-Oh Wi),김정근(Jung-Kun Kim),임영철(Young-Cheol Lim),정영국(Young-Gook Jung) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
In this paper, 2 phase modulated SRPP-PWM<br/> (Separately Random Pulse Position PWM) is proposed. This PWM technique is based on the 2 phase modulated SVPWM(Space Vector Pulse width Modulation). In according to the theory of SVPWM, 2 phase modulated SVPWM uses two pulses, not three pulses as in 3 phase modulated SVPWM. In the proposed SRPP- PWM scheme, each of two phase pulses is located randomly in each switching interval. The experimental results show that the voltage and switching noise harmonics are spread to a wide band area Also, the performance of the proposed 2 phase modulated SRPP- PWM and the conventional SVPWM are compared to each other. In result, the speed response is nearly similar to each other from the viewpoint of the v/f constant control
한석태(Seog-Tae Han),강지만(Jinman Kang),이정원(Jeong-Won Lee),제도흥(Do-Hyung Je),정문희(Moon-Hee Jung),김수연(Soo-Yeon Kim),위석오(Seog-Oh Wi) 한국전자파학회 2010 한국전자파학회논문지 Vol.21 No.11
본 논문에서는 밀리미터파 수신 시스템의 준광학계 회로에서 발생되는 3가지 빔 결합 손실에 대하여 가우시언 빔 전송 이론을 기반으로 심도 있게 검토하였다. 첫째, 준광학 시스템에 의하여 형성된 각각의 빔 허리와 그들의 위치가 서로 일치되지 않았을 때 발생되는 빔 결합 손실에 대하여 분석하였다. 빔 허리의 크기를 3 이상으로 설계하면 빔 광축 방향에 대한 빔 허리 크기와 그 위치의 불일치에 의한 빔 결합 손실을 최소화 시킬수 있다. 둘째, 준광학 회로에서 서로 다른 두 빔 축의 기울어짐과 각도상의 비정렬에 의한 빔 결합 손실을 해석하였다. 기울기 각도와 정렬에 의한 빔 결합 손실을 고려할 때 빔 허리의 크기가 작을수록 유리함을 알 수 있다. 마지막으로 광축 방향에 대하여 측면 방향으로 하나의 광축이 치우쳐 있는 경우의 결합 손실을 검토하였다. 치우침을 감안한 설계 빔의 반경은 최소한 3 이상이 되도록 설계되어야 한다. In this paper, three kinds of beam coupling losses which occur in a quasi-optics circuit for millimeter wave receiver system have been intensively investigated. First, the beam coupling losses which are caused by mismatch of beam waists radii and their positions between those of one and the other have been evaluated. It shows that beam coupling losses due to mismatch of beam waists radii and their positions between two quasi-optics circuits can be minimized if beam waist radius is chosen as larger than 3 times the operation wavelength. Second, the beam coupling losses have been studied when the axis of propagation of one beam is tilted with respect to that of the other beam. It is noted that smaller beam waist radius results in greater tolerance to tilts and angular misalignments. Third, the beam coupling cases in which two beams are offset if their axes of propagation are parallel but one is displaced relative to the other have been investigated. It is confirmed that beam waists radii with larger than 3 times operation wavelength are less sensitive to lateral offsets.
새로운 3상 랜덤 펄스 위치 PWM기법에 의한 EPLD기반의 모터 속도제어 시스템
김회근(Hoe-Geun Kim),위석오(Seog-Oh Wi),임영철(Young-Cheol Lim),정영국(Young-Gook Jung),나석환(Seok-Hwan Na) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
In tins paper, EPLD(Erasable Programmable Logic Device) based induction motor drives with a SRP-PWM(Separatley Randomized Pulse Position PWM) is proposed in the proposed RPWM (Random PWM), each of three phase pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. To verify the validity of the proposed RPWM, the experimental study was tried Along With the randomization of PWM pulses, the space vector modulation is also executed in the TMS32OC31 DSP(Digital Signal Processor) The experimental results show that the voltage and switching noise harmonics are spread to a Wide band area Also, the performance of the proposed SRP- PWM and the conventional SVM-PWM are nearly the same from the viewpoint of the v/f constant control
오세진,노덕규,김광동,송민규,제도흥,위석오,김태성,OH SE-JIN,ROH DUK-GYOO,KIM KWANG-DONG,SONG MIN-GYU,JE DO-HEUNG,WI SEOG-OH,KIM TAE-SUNG,WHITNEY ALAN R. 한국천문학회 2004 天文學論叢 Vol.19 No.1
In this paper, we introduce the development of the large storage system in order to record the observed space radio signal in the Korean VLBI Network(KVN) with high-speed. The KVN is the Very Long Baseline Interferometery(VLBI) to observe the birth of star, the structure of space by constructing radio telescope with diameter 21m at the Seoul, Ulsan, Jeju from 2001 to 2007 years. To do this, Korea Astronomy Observatory joined the international consortium for developing the high-speed large storage system(Mark 5), which is developed by MIT Haystack observatory. The Mark 5 system based on hard disk has to record up to 1 Gbps the observed space radio signal. The main features of Mark 5 system are as follows; First it is able to directly record the input data to the hard disk without PC1(Peripheral Component Interconnect) internal bus, and the second, it has two hard disk banks, which are able to hot-swap ATA/IDE type very cheap up to 1 Gbps recording and playback. The third is that it follows the international VLBI standard interface hardware(VSI-H). Therefore it can be connect directly the VSI-H type system at the input/output. Finally it also supports e- VLBI(Electronic-VLBI) through the standard Gigabits Ethernet connection.
오세진,노덕규,김광동,정현수,제도흥,위석오,한석태,김현구,Oh, Se-Jin,Roh, Duk-Gyoo,Kim, Kwang-Dong,Chung, Hyun-Soo,Je, Do-Heung,Wi, Seog-Oh,Han, Seog-Tae,Kim, Hyun-Goo 한국천문학회 2005 天文學論叢 Vol.20 No.1
In this paper, we propose a small-scale Gigabit VLBI observing system for the Korean VLBI Network (KVN) under construction. The system consists of high-speed sampler, IP-VLBI board, PC-VSI board, and software correlator. Radio signal received by receiver is sampled by high-speed sample. at 1 Gsps (Gigabit sample per second) rate with 2 bits quantization. The digitized signal is recorded in PC and the software correlator does the cross correlation. IP-VLBI board will be used for the geodesy VLBI observation, while PC-VSI board is for the astronomical VLBI observation. The PC-VSI board adopts the VSI-H (VLBI Standard Interface Hardware). The proposed system is based on commercial PCs and therefore can be built inexpensively.