http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
한운동 ( Wun-dong Han ),지평식 ( Pyeong-shik Ji ) 한국산업융합학회 2006 한국산업융합학회 논문집 Vol.9 No.2
Harmonics happened due to nonlinear systems such as UPS, SCR controlled motors, and fluorescent lighting in distribute power system is very important subject to optimal operation and control of power system. Harmonics sometimes make incorrect operation of protective relaying system under normal condition on power system. In this study, total harmonics distortion(THD) of power were measured and analyzed by the field test on electrical facilities which were installed at the rural industrial complex in Chungbuk province. In addition, the deprivation of power factor by harmonics and the content of THD which is measured at neutral line was researched.
동적전압보상시스템에서 LC필터 전압궤환의 제어특성 비교
한운동 한국교통대학교 2015 한국교통대학교 논문집 Vol.50 No.-
Dynamic voltage restorers(DVRs) are mainly used to protect sensitive loads from the electrical network voltage disturbances such as sags or swells and could be used to reduce harmonic distortion of ac voltages. The typical DVR topology essentially contains a voltage source inverter (VSI) with LC Filter, an injection transformer connected between the ac voltage line and the sensitive load, and a DC energy storage device. For injecting series voltage, the PWM inverter is used and the low pass filter consist of inductor(L) and capacitor(C) eliminates the harmonics of the PWM voltage of the inverter. However there are voltage pulsation responses by the characteristic of the LC lowpass filter that eliminate the harmonics of the PWM output waveform of the inverter. Therefore, this paper compared control and frequency response characteristic of LC filter voltage feedback with the DVRs. The voltage control by LC filter should be connected in the line side since this feedback method allows a relatively faster dynamic response, enabling the elimination of voltage notches or spikes in the beginning and in the end of sags and strong load voltage THD reduction.
한운동 忠州大學校 2009 한국교통대학교 논문집 Vol.44 No.-
In this study, PI current controller was designed to control high frequency resonant ballast for high voltage discharge lamps. To get power modulation and spectrum diffusion effect with PWM and pulse width modulation of lamp current, 200[Hz] of low frequency signal was applied to input of current controller. Also, arc stability was investigated according to frequency of modulation wave and modulation rate. electronic ballast for 250[W] high voltage discharge lamp was manufactured. proposed pulse width modulation reduce acoustic resonance and usefulness of designed controller was confirmed.
진폭 변조을 이용한 MHD 램프용 공진 인버터 안정기의 설계
한운동 忠州大學校 2010 한국교통대학교 논문집 Vol.45 No.-
In this paper, energy saving electronic ballast that efficiency was improved more than conventional ballast was designed. The proposed electronic ballast consists of a resonance circuit using PWM. Frequency lower than conventional frequency was adopted to suppress EMI.
3상 정류기의 고조파 경감을 위한 스위칭 회로에 관한 연구
한운동 韓國交通大學校 2013 한국교통대학교 논문집 Vol.48 No.-
In this paper, a new control circuit for shaping the line current and reducing the total harmonics distortion in three phase diode rectifier is presented. In the past years, three phase diode rectifier have been used widely. Because a three-phase diode rectifier don't need controller, it's a cheap and reliable method to get DC voltage. However an harmonics problems which make an acoustic noise, overheat, a disorder of computer system and sometimes mess a communication system are caused. In an uncontrolled diode rectifier, current is drawn from the ac mains only during the period in the ac cycle when the instantaneous voltage is greater than the voltage across the dc-link capacitor. As a result, current is of pulsed nature with the amplitude dependent on the size of the capacitor. a pulsed natured current is so discontinuous that it makes a harmonics problems. In this study, the three bidirectional switches rated at very small power are installed in a conventional three phase diode rectifier. Using those switches, an idle current charges to capacitors continuously. Simulation's and Experimental's results demonstrate a reduction of harmonics, a improvement of power factor and THD.
한운동 충주대학교 2006 한국교통대학교 논문집 Vol.41 No.-
The role of the inverter-side filter used in the dynamic voltage restorer (DVR) is examined. Using circuit analysis method, it is shown that the selection of the filter parameters can affect the DVR inverter rating. Furthermore, with the DVR filter-series injection transformer combination, the loading effect of the filter on the restorer and the primary supply system has been quantified under normal as well as voltage sag conditions. A systematic filter design method is then proposed, the primary objective of which is to achieve specific harmonic performance while ensuring that the DVR inverter rating and the loading effect are minimized. Illustrative examples are also included.
HVDC System용 승압형 Converter설계에 관한 연구
한운동 忠州大學校 2011 한국교통대학교 논문집 Vol.46 No.-
Switching technique in conventional HVDC transmission system depends on line-commutation of the high power semiconductor switches with fast turn-off capability from the gate, such as Gate turn-off switches(GTO’s). The boost type SVPWM converter has very useful characteristics. One of the main objective of this paper is to show that the useful characteristics is applicable to improve the operation capabilities of the HVDC station. In this study, the boost type SVPWM converters exercise direct control over the voltage amplitude, the voltage angle, and the frequency. the proposed system improved that the SVPWM inverter with the force-commutated in HVDC system is very useful and the feasible system.
特定高調波 除去方式에 依한 交流 制御用 Inverter 硏究
韓運東,池平植 충주대 2004 産業科學論文集 Vol.12 No.-
In electrical industry, development of inverter technique make to control AC motor precisely. So the using inverter spreads fast. The motor using inverter has high efficiency, characteristic of constant torque, output and etc. However, in spite of many good things of using inverter, VS-Motor is used widely because of simple control and cheap cost. VS-Motor is speed control method using eddy-current coupling. This method installs eddy-current coupling with constant speed driving induction motor and controls rotating speed through a charging change of a excitation current, particularly. But this method has large losses and low efficiency because of heating as slip drum in low speed region. In cooling, addition of a mechanical devices is difficult and in volume, large space is occupied. Using SCR for control, efficiency of system is low. In case of inverter, though advantage of high efficiency and high performance the price is expensive. Therefore, in this study, we developed VVVF Inverter system for controlling AC power. A using micro-controller can make the price down and it has many devices so it can be expected the system's compact and low noise effect.