• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1991년도 하계학술대회 논문집
• /
• pp.587-590
• /
• 1991

It is general to make the circuit analysis of current-fed type inverter driven by current source with rippleless input under the assumption of infinite induction Ld in direct current reactor(DCL). This paper focusing on the fact that Ld has bounded value in real circuit, examines operating characteristics by analysis of static state characteristics of current type inverter driven by voltage source and compares it with the operating characteristics of the circuit driven by current source.

• 대한전자공학회논문지SD
• /
• 제43권10호
• /
• pp.61-67
• /
• 2006

본 논문에서는 Poly-Si의 불규칙한 Grain boundary 분포로 인해 발생하는 문턱전압의 변화에 대해서도 일정한 전류를 흘려줄 수 있는 전류원을 제안하였다. 기존의 문턱전압 보상 전류원에 비해 넓은 입력전압 범위에서도 포화영역의 특성이 매우 향상되었으며 문턱전압의 변화에 따른 전류의 오차를 감소시킬 수 있었다. 마지막으로 HSPICE 시뮬레이션 과정을 통해 Poly-Si TFT의 특성곡선과 제안된 전류원의 특성곡선을 비교하였으며 각각의 입력전압에 대한 문턱전압의 변화에 따른 출력전류의 상대오차를 측정하였다.

• 전력전자학회논문지
• /
• 제10권5호
• /
• pp.443-449
• /
• 2005

본 논문에서는 연료 전지 시스템을 위한 Z-소스 인버터로 구성된 병렬 운전 시스템을 제시 하였다. PWM 방식으로는 Carrier phase shifted SPWM을 적용하였으며 이 방식은 출력 전류의 고조파 성분을 줄일 수 있는 장점을 갖는다. 그러나 이 기법을 Z-소스 인버터로 구성된 병렬 운전 시스템에 적용하는 경우 추가적으로 순환 전류를 발생한다. Z-소스 인버터로 구성된 병렬 운전 시스템이 동작 시 발생하는 순환 전류를 분석하고 순환 전류를 감소시키며, 부하전류에 낮은 고조파 성분을 가질 수 있도록 순환 전류 리액터를 사용하였다. 이에 대한 적합성을 시뮬레이션과 실험을 통해 입증하였다.

• Journal of Power Electronics
• /
• 제10권3호
• /
• pp.285-292
• /
• 2010

This paper presents a current mode integrated control technique (CM-ICT) using a modified voltage space vector modulation (MSVM) for Z-source inverter (ZSI) fed induction motor drives. MSVM provides a better DC voltage boost in the dc-link, a wide range of AC output voltage controllability and a better line harmonic profile. In a voltage mode ICT (VM-ICT), the outer voltage feedback loop alone is designed and it enforces the desired line voltage to the motor drive. An integrated control technique (ICT), with an inner current feedback loop is proposed in this paper for the purpose of line current limiting and soft operation of the drive. The current command generated by the PI controller and limiter in the outer voltage feedback loop, is compared with the actual line current, and the error is processed through the PI controller and a limiter. This limiter ensures that, the voltage control signal to the Z-source inverter is constrained to a safe level. The rise and fall of the control signal voltage are made to be gradual, so as to protect the induction motor drive and the Z-source inverter from transients. The single stage controller arrangement of the proposed CM-ICT offers easier compensation. Analysis, Matlab/Simulink simulations, and experimental results have been presented to validate the proposed technique.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1997년도 전력전자학술대회 논문집
• /
• pp.370-373
• /
• 1997

In this paper, we compose of the stepdown chopper and the current source inverter. Because dc side current of the current source inverter pulse with twice frequency of utility, we control that modulation factor of chopper is pulsed twice frequency. Therefore if voltage across the dc reactor equal to zero, it tis decreased. And we control modulation factor of the chopper to operate at maximum power point around of solar cell.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1999년도 전력전자학술대회 논문집
• /
• pp.489-492
• /
• 1999

This paper proposes a control method for three-phase voltage-source PWM converters using only a single current sensor in the DC link. A predictive current controller for the voltage-source PWM converter is used so that all phase currents can be reconstructed in a switching period although one or two of active vectors are applied only for a short time. Compensation of the 2 step delays is also included. In this paper single sensor current control using predictive state observer will be discussed, and investigated experimentally.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술대회 논문집 전문대학교육위원
• /
• pp.24-27
• /
• 2003

In this paper, We make experiment on two methode for GaAs MESFET with temperature variation. One method, we mesure gate leakage current at open source electrode. another we mesure gate leakage current at short source electrode. The difference of two current has been tested and provide that the existence of another source to Schottky barrier height against the image force lowering effect.

• 천문학논총
• /
• 제27권4호
• /
• pp.105-109
• /
• 2012

The current status of the AKARI-FIS Point Source Catalogue is reported. The first version of the Bright Source Catalogue has been in public since March 2010 and used extensively in the various fields in astronomy. The second version of the Bright Source Catalogue and the first version of the Faint Source Catalogue are currently under development. The revised Bright Source Catalogue is expected to have improved completeness, reliability, and accuracy compared to the current version. The Faint Source Catalogue will have a scan-density dependent detection limit and will enable much deeper exploration of the sky especially in the high-ecliptic latitude regions. Both catalogues will be available in a year time scale.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제55권5호
• /
• pp.258-264
• /
• 2006

This paper presents an integrative control scheme for series-type active power filters combined with shunt passive filters not only to compensate for the source voltage unbalance and current harmonics but also to correct the power factor. To reduce the power capacity of the active filters, passive filters are connected in parallel. Diode rectifiers are replaced by the PWM converters in order to feed the real power back to the source. Power factor control is performed by changing the phase of the load voltage so that the phase of the source current coincides with that of the source voltage. The resultant voltage reference is the addition of the voltage component compensating for the source voltage unbalance and harmonic currents and the voltage component correcting the power factor. The validity of the proposed algorithm has been verified by experimental results.

• 전력전자학회논문지
• /
• 제20권5호
• /
• pp.410-420
• /
• 2015

This paper provides a comparison of power converter loss and thermal description for voltage source and current source type 5 MW-class medium-voltage topologies of wind turbines. Neutral-point clamped three-level converter is adopted for a voltage source type topology, whereas a two-level converter is employed for current source type topology, considering the popularity in the industry. To match the required voltage level of 4160 V with the same switching device of IGCT as in the voltage source converter, two active switches are connected in series for the case of current source converter. Transient thermal modeling of a four-layer Foster network for heat transfer is done to better estimate the transient junction and case temperature of power semiconductors during various operating conditions in wind turbines. The loss analysis is confirmed through PLECS simulations. Comparison result shows that the VSC-based wind turbine system has higher efficiency than the CSC under the rated operating conditions.