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조국춘(Cho Goog-Chun),박채운(Park Chae-Woon),최종묵(Choi Jong-Mook) 한국철도학회 1999 한국철도학회 학술발표대회논문집 Vol.- No.-
Three phase full bridge rectifier has been used to obtain de voltage from three phase ac voltage source. The rectifier system has drawbacks that power factor is low and power flow is unidirectional. Therefore, when de voltage increases due to regeneration of power, the dynamic resistor for dissipation of regeneration power must be installed. But three phase PWM converter can be controlled to operate with unity power factor and bidirectional power flow. Therefore when the PWM converter is used as dc supply system, the dissipating resistor is not necessary. On this thesis, in order to design a controller having good performance, the three phase PWM converter is completely modeled by using circuit DQ-transformation and thus a general and simple instructive equivalent circuit is obtained; the inductor set becomes a second order gyrator-coupled system and three phase inverter becomes a transformer as well. Under given phase angle(α) and modulation index(MI) of the three phase inverter, the de and ac characteristics are obtained by analysis of the transformed equivalent circuit. The validity of the equivalent circuit is confirmed through PSPICE simulation. And based on the de and ac characteristics a controller with unity power factor is proposed.
100 kVA GTO 전압원 인버터를 사용한 정지형 무효전력보상기
최남섭,조국춘,정구호 여수대학교 1998 論文集 Vol.13 No.2
A stactic VAR compensator using 100 kVA three-level GTO voltage source inverter is presented for high voltage, high power application. The phase angle of the voltage source inverter is controlled so as to compensate the reactive power of some three-phase load. This paper deals with the following topics: system description, circuit DQ modelling, main controller, power circuit. The experimental results show good characteristics for var compensation.
Analysis and Controller Design of Reactive Power Compensator with Three-level Inverter
Choi, Nam-Sup,Cho, Guk-Choon,Kim, Kyung-Min 여수대학교 1998 論文集 Vol.13 No.2
본 논문에서는 회로 DQ 변환을 사용하여 3-레벨 인버터를 사용한 무효전력보상기의 DC 특상 및 AC특성등의 완전한 동작특성을 해석하고, 이러한 시스템에 feedback 및 feedforward 제어 루프를 도입하여 인버터 제어변수인 진폭변조지수(MI)와 DC측 커패시터 전압을 decoupling하여, DC측 커패시터 전압을 일정한 수준으로 유지하면서도 1 사이클 이내의 빠른 응답 특성을 갖는 제어기를 제안한다. 또, 이러한 해석과 제어기 설계의 타당성은 실험으로 확인하였다.
Opposite 필터를 적용한 가변 Q 디지털 그래픽 이퀄라이저
이용희,김인철,조국춘 대한전자공학회 2004 電子工學會論文誌-SP (Signal processing) Vol.42 No.2
This paper proposes a variable-Q digital graphic equalizer with the opposite filters. A method for designing the proposed equalizer is also presented. In the proposed variable-Q equalizer, we adjust the Q-factor of the equalizer filter depending on the gain, yielding an improved equalizer performance. Also, by increasing the Q-factor of the opposite filters gracefully as the gain becomes greater, the inter-band interference can be removed effectively. We shall show that the frequency response of the proposed equalizer can reproduce the user's gain setting faithfully. 본 논문에서는 opposite 필터를 적용한 가변 Q 디지털 그래픽 이퀄라이저를 제안한다. 그리고 제안한 이퀄라이저를 설계하는 방법을 제시한다. 본 논문에서 제안하는 가변 Q 이퀄라이저에서는 이퀄라이저의 성능을 개선하기 위해서 이득에 따라 이퀄라이저 필터의 Q-factor를 조정한다. 또한, opposite 필터의 Q-factor를 이득이 높아짐에 따라 완만하게 증가하도록 설정함으로써 opposite 필터가 대역간 간섭을 효과적으로 제거할 수 있게 한다. 실험을 통해 제안한 opposite 필터를 적용한 가변 Q 이퀄라이저는 사용자가 설정한 이득을 매우 충실하게 표현함을 보이겠다.
Opposite 필터를 적용한 가변 Q 디지털 그래픽 이퀄라이저
이용희,김인철,조국춘 대한전자공학회 2004 電子工學會論文誌-SP (Signal processing) Vol.41 No.04
This paper proposes a variable-Q digital graphic equalizer with the opposite filters. A method for designing the proposed equalizer is also presented. In the proposed variable-Q equalizer, we adjust the Q-factor of the equalizer filter depending on the gain, yielding an improved equalizer performance. Also, by increasing the Q-factor of the opposite filters gracefully as the gain becomes greater, the inter-band interference can be removed effectively. We shall show that the frequency response of the proposed equalizer can reproduce the user's gain setting faithfully. 본 논문에서는 opposite 필터를 적용한 가변 Q 디지털 그래픽 이퀄라이저를 제안한다. 그리고 제안한 이퀄라이저를 설계하는 방법을 제시한다. 본 논문에서 제안하는 가변 Q 이퀄라이저에서는 이퀄라이저의 성능을 개선하기 위해서 이득에 따라 이퀄라이저 필터의 Q-factor를 조정한다. 또한, opposite 필터의 Q-factor를 이득이 높아짐에 따라 완만하게 증가하도록 설정함으로써 opposite 필터가 대역간 간섭을 효과적으로 제거할 수 있게 한다. 실험을 통해 제안한 opposite 필터를 적용한 가변 Q 이퀄라이저는 사용자가 설정한 이득을 매우 충실하게 표현함을 보이겠다.
단상시스템에서 벡터적(vector product)에 의한 동기 루프
배기훈,기상우,조국춘,최종묵 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
A Diode bridge rectifier and a phase-controlled thyristor bridge rectifier generate harmonics in power system. Nowadays, power factor and harmonics are important performance in electrical equipment for railway vehicle. Many researchers have been trying to improve the power factor and ac-side harmonics. Therefore the PWM converter has been used to operate at unity power factor and to reduce ac-side current harmonics. This paper proposes the synchronization loop by vector product in single-phase PWM converter. The proposed control method can realize the sinusolidal input current waveform and the effective unity power factor. The validity of the proposed control method is verified through the experimental result.
Arm Short 보호 기능을 포함한 다기능 IGBT GATE DRIVER
이경복(Lee Kyung-Bok),조국춘(Cho Goog-Chun),최종묵(Choi Jong-Mook) 한국철도학회 2000 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper introduces the main function and protection method of IGBT gate driver that designed by KOROS. Recently, the applications of insulated gate bipolar transistors(IGBTs) have expanded widely, particularly in the area of railway converters. This driver is suitable for railway traction applications, so they are designed for circumstance of railway vehicle such as vibration. The input control power for this driver is supplied from battery charger of railway. it is no necessary an isolated power supply board or auxiliary power supply, with substantial savings in cost and space in railway applications. This gate driver can be used wide range of input voltage. So, performance of the driver has no relation with the battery voltage(70V~110V). The protection methods of IGBT gate driver have many kind of ways, but this gate driver is designed to apply to converter for railway system, so this gate driver includes protection for arm short current and low control power voltage, etc. And the process of protection method and protection reference value are optimized by means of sufficient test with our own facilities.