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Analysis of Flux Observers Using Parameter Sensitivity
H.T.Nam,K.J.Lee,J.W.Choi,H.G.Kim,T.W.Chun,E.C.Noh 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
To achieve a high performance in direct vector control of induction motor, it is essential to correct estimation of rotor flux The accuracy of flux observers for induction machines inherently depends on parameter sensitivity This paper presents an analysis method for conventional flux observers using Parameter Sensitivity The Parameter sensitivity is defined as the ratio of the percentage change in the system transfer function to the percentage change of the parameter variation We define the ratio between real flux and estimated flux as the transfer function, and analyzed a parameter sensitivity of this transfer function by simulation.<br/>
플라이휠 저장에너지 UPS의 성능 시험을 위한 순간정전 및 전압불평형 발생기
김중원(J.W. Kim),이기수(K.S. Lee),변우열(W.Y, Byeon),노의철(E.C. Nho),김인동(I.D. Kim),전태원(T.W. Chun),김흥근(H.G. Kim) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
This paper deals with a novel 3-phase power quality disturbance generator. The proposed generator can be applied to the performance that of custom power devices. Voltage sag, swell, outage unbalance and phase shift are provided by the generator. The control scheme for the disturbance generation is simple, and hardware setup is cost effective compared with conventional scheme. The operating principle of the generator is described and the usefulness verified through simulation with 10㎸A power rating.
T.Y. Cho,J.H. Yoon,K.S. Kim,W. Fang,Y.K. Joo,K.O. Song,S.J. Youn,S.Y. Hwang,H.G. Chun 한국표면공학회 2007 한국표면공학회지 Vol.40 No.4
High Velocity Oxygen Fuel (HVOF) thermal spray coating of nano size WC-Co powder (nWC-Co) has been studied as one of the most promising candidate for the possible replacement of the traditional hard plating in some area which causes environmental and health problems. nWC-Co powder was coated on Inconel 718 substrates by HVOF technique. The optimal coating process obtained from the best surface properties such as hardness and porosity is the process of oxygen flow rate (FR) 38 FMR, hydrogen FR 57 FMR and feed rate 35 g/min at spray distance 6 inch for both surface temperature 25℃ and 500℃. In coating process a small portion of hard WC decomposes to less hard W₂C, Wand C at the temperature higher than its decomposition temperature 1,250°C resulting in hardness decrease and porosity increase. Friction coefficient increases with increasing coating surface temperature from 0.55-0.64 at 25℃ to 0.65-0.76 at 500℃ due to the increase of adhesion between coating and counter sliding surface. Hardness of nWC-Co is higher or comparable to those of other hard coatings, such as A1₂O₃, Cr, Cr₂O₃ and HVOF Tribaloy 400 (T400). This shows that nWC-Co is recommendable for durability improvement coating on machine components such as high speed spindle.
3상 다이나믹 UPS 성능 시험을 위한 Sag-Swell 발생기
김중원(J.W. Kim),이기수(K.S. Lee),변우열(W.Y. Byun),노의철(E.C. Nho),김인동(I.D. Kim),전태원(T.W. Chun),김흥근(H.G. Kim) 한국조명·전기설비학회 2004 한국조명·전기설비학회 학술대회논문집 Vol.2004 No.5월
This Paper describes a new 3 phase Sag-Swell generator for the test of custom power devices such as UPS, DVR, DSTATCOM, SSTS, etc. The proposed scheme has good features of simple structure, high reliability, wide range of sag and swell variation. It can also generate voltage outage. The control scheme for the generation is simple. The operation principle of the proposed scheme is described and verified through simulations.
Development of Low-Cost Drive System of a Small-Size Electric Vehicles
T.T.Vu,D.T.Lien,T.W.Chun,H.H.Lee,H.G.Kim,E.C Nho 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper develops the low-cost drive system of the small-size electric vehicles (EVs) driven by the brushed dc motor. The power circuit for driving the dc motor is designed by considering both the cost and efficiency. Some MOSFET and diodes at the power converter are connected in parallel for reducing the conduction loss. In order to change smoothly the rotating direction of dc motor, an operating sequence for both the field current and the armature voltage according to the accelerator pedal angle is suggested. Through the simulation studies and experimental results with the low-cost 8-bit AVR, the performances of the proposed methods are verified.
다이오드 클램프형 3-레벨 IGBT 인버터를 위한 과전압 방지 스너버 회로
정재헌(J.H. Jung),송웅협(W.H. Song),노의철(E.C. Nho),김인동(I.D. Kim),김흥근(H.G. Kim),전태원(T.W. Chun),유동욱(D.W. Yoo) 전력전자학회 2009 전력전자학술대회 논문집 Vol.2009 No.1
This paper proposes a new snubber circuit for a diode-clamped 3-level IGBT inverter. The voltage spike at the instant of IGBT turn-off switching can be reduced considerably by the proposed scheme. The operation of the proposed snubber circuit is described and one pole of a 3-level IGBT inverter has been implemented. The simulation and experiment was carried out with 250V dc link voltage and 20A peak load current. The usefulness of the proposed snubber circuit is verified through experimental results.