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RISS 인기검색어
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- 저자 : 서기영(Ki-Young Shu) (검색결과 4 건)
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Inverter Air-conditioner Power System with Low Power Dissipation Type using Micro-controller
문상필(Sang-Pil Mun),서기영(Ki-Young Shu),김주용(Ju-Yong Kim),김광태(Kwang-Tae Kim) 한국조명·전기설비학회 2004 한국조명·전기설비학회 학술대회논문집 Vol.2004 No.5월
When using a conventional power factor correction circuit, a comparatively huge capacitor is used to boost-up output voltage. It has a large amount of harmonic distortion in the input current waveform. To improve the input current waveform of diode rectifiers, we propose a new operating principle for the power factor correction circuit. Due to the fact that the proposed circuit uses smaller ones and a smaller reactor, the output voltage increases and obtains higher input current waveform. These are suitable for the harmonics guidelines. The proposed circuit is able to obtain higher power factor and efficiency. Also, it has reduced switching loss and held over-shooting by using an inverter of eliminated dead-time HPWM that has non-linear impedance circuits to make up diodes, capacitance and a reactor. We compared the conventional PWM inverter and proposed HPWM inverters and found that a high input power factor of 97[%] and an efficiency of 98[%] were also obtained.
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김칠용(Chil-Yong Kim),문상필(Sang-Pil Mun),조만철(Man-Chul Cho),서기영(Ki-Young Shu),권순걸(Soon-Kurl Kwon) 한국조명·전기설비학회 2007 한국조명·전기설비학회 학술대회논문집 Vol.2007 No.5월
For small capacity rectifier circuits such as these for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. The absence of switching devices makes systems more tolerant to over -load, and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method, It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and expermental implementations.
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저손실 스너버 회로를 이용한 유도전동기의 서지전압 억제
조만철(Man-Chul Cho),문상필(Sang-Pil Mun),김칠용(Chil-Yong Kim),김주용(Ju-Yong Kim),서기영(Ki-Young Shu),권순걸(Soon-Kurl Kwon) 한국조명·전기설비학회 2007 한국조명·전기설비학회 학술대회논문집 Vol.2007 No.5월
The development of advanced Insulated Gate Bipolar Transistor(IGBT)has enabled high-frequency switching operation and has improved the performance of PWM inverters for motor drive. However, the high rate of dv/dt of IGBT has adverse effects on motor insulation stress. In many motor drive applications, the inverter and motor are separated and it requires long motor feds. The long cable contributes high frequency ringing at the motor terminal and it results in hight surge voltage which stresses the motor insulation The inverter output filter and ROC snubber are conventional method which can reduce the surge voltage. In this paper, we propose the new low loss snubber to reduce the motor terminal surge voltage. The snubber consists of the series connection of charging/discharging capacitor and the voltage-clamped capacitor. At IGBT turn-off, the snubber starts to operate when the IGBT voltage reaches the voltage-clamped level. Since dv/dt is decreased by snubber operating, the peak level of the surge voltage can be reduced. Also the snubber operates at the IGBT voltage above the voltage-clamped level, the snubber loss is largely reduced comparing with ROC snubber. The proposed snubber enables to reduce the motor terminal surge voltage with low loss.
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三相 誘導電動機의 運轉을 위한 새로운 Optimal PWM方式에 관한 硏究
李允鐘,徐基永 慶南大學校 附設 工業技術硏究所 1987 硏究論文集 Vol.5 No.-
誘導電動機를 可變速 運轉할 때 인버어터를 사용하게 되는데 이때 인버어터의 스위칭作用으로 많은 高調波가 포함된다. 이러한 高調波의 영향을 低減시키기 위하여 이전에는 Optimal PWM方式으로 적절한 評價函數를 選定하고 이를 最小化하여 最適 스위칭패턴을 결정하였다. 그러나 스위칭角을 계산하는 시간이 많이 소요되므로 이러한 點을 改善하기 위하여 誘導電動機를 간단한 等價回路로 변환하여 계산시간을 줄이기 위한 새로운 Optimal方式을 提案하였다. 本 새로운 Optimal PWM方式의 妥當性을 立證하기 위하여 시뮬레이션解析으로 인버어터의 高調波영향, 線間電壓 등을 分析, 檢討하여 종래의 他方式(Natural PWM, Optimal PWM)과 比較하였으며 그 중요한 結果들을 提示하였다. A great deal of higher harmonics are produced through inverter switchings when an induction motor is operated by variable speed. An appropriate evaluation function for optimal PWM switching strategy using an inverter has been selected so as to reduce the effects of higher harmonics and to determine an optimised switching pattern. Because the calculation of switching angles takes in general much time, a new optimal PWM strategy is proposed with emphasis on the reduction of calculation time through conversion to a simple equivalent circuit in the induction motor. In this paper some important experimental results about the effects of higher harmonics and line voltages are compared with the conventional methods(Natural PWM, Optimal PWM) by simulation analysis that results in proving the appropriateness of this new optimal PWM strategy.
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