• Journal of Power Electronics
• /
• v.13 no.4
• /
• pp.712-718
• /
• 2013

This paper proposes a control method for reducing the total harmonic distortion (THD) of the grid current of three-phase grid-connected inverter systems when the grid voltage is distorted. The THD of the grid current caused by grid voltage harmonics is derived by considering the phase delay and magnitude attenuation due to the hardware low-pass filter (LPF). The Cauchy-Schwarz inequality theory is used in order to search more easily for the minimum point of the THD. Both the gain and angle of the compensation voltage at the minimum point of the THD of the grid current are derived with the variation of cut-off frequencies of the hardware LPF. Simulation and experimental results show the validity of the proposed control methods.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1922-1923
• /
• 2002

본 논문은 편광 유지 광섬유 루프 미러를 이용한 색분산 보상 필터의 제안과 이의 응용에 관한 것이다. 제안된 필터는 구성이 간단하고, 편광 의존성이 낮으며 하나의 장비로 여러 채널의 신호를 동시에 분산 보상할 수 있는 장점이 있다. 실험에 사용된 커플러의 파워-커플링 계수를 조절하면 그룹 딜레이 기울기를 조절할 수 있다. 그리고 n개의 편광 유지 광섬유 루프 미러클 연결하면 필터의 손실이 커지지만 커플링 계수의 조절을 통해 필터 특성을 변화시킬 수 있다. 이와 같은 특성을 이용하면 제안된 필터를 동적 분산 보상기로 이용할 수 있다. 논문에서는 파워-커플링 계수의 변화에 따른 필터의 그룹 딜레이 기울기의 변화를 계산한 그래프와 실험 결과 데이터를 비교 제시하였다.

• Journal of the Korean Society of Industry Convergence
• /
• v.2 no.2
• /
• pp.103-108
• /
• 1999

The paper describes a implementation of space vector pulse-width modulation voltage source inverter and interfacing of DSP using field programmable gate array(FPGA) for a induction motor vector control system. The implemented chip is included logic circuits for SVPWM, dead time compensation and speed detection using Quick Logic, QLl6X24B. The maximum operating frequency and delay time can be set to 110MHz and 6 nsec. The designed Application Specific Integrated Circuit(ASIC) for SVPWM can be incorporated with a digital signal processing to provide a simple and effective solution for high performance induction motor drives with a voltage source inverter. Simulation and implementation results are shown to verify the usefulness of ASIC in a motor drive system and power electronics applications.

• Proceedings of the KIEE Conference
• /
• 1998.07f
• /
• pp.1993-1995
• /
• 1998

The compensation problem of error and various problems due to delay of speed sensor itself and speed detection have issued in case using speed sensor in the adjustable speed control of induction motor. This paper have applied the stator flux oriented vector control algorithm and space voltage vector PWM method in order to improve an dynamic character of voltage-source inverter system, and also used the better IP controller in the speed response than Pl controller as speed controller. This paper estimated the rotator speed using input current of inductor motor and flux component invoked through voltage drop by terminal voltage and stator resistor.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.5
• /
• pp.30-41
• /
• 1999

본 논문에서는 연속시간과 이산시간에서 파라미터 불확실성과 시간지연을 가지는 비선형시스템에 대한 퍼지 견실 H∞ 제어기 설계방법을 제시한다. 비선형시스템은 변형한 T-S(Takagi- Sugeno) 퍼지모델을 사용하여 나타내고, 퍼지제어는 PDC(parallel distributed compensation) 개념을 이용한다. 또한 Lyapunov 접근방법을 이용하여 불확실성, 외란과 시간지연을 가지는 변형한 T-S 퍼지모델의 H∞ 노옴 한계를 가지는 자승적 안정성을 언급하고, LMI(linear matrix inequality) 기법을 이용하여 퍼지 견실 H∞ 제어기의 존재 조건과 제어기 설계방법을 제시한다. 그러므로 제시한 기법은 구하여진 충분조건을 만족하는 해를 찾음과 동시에 제어기를 한번에 설계할 수 있다. 마지막으로 예제를 통하여 제시한 방법의 타당성을 확인한다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2001.05a
• /
• pp.161-165
• /
• 2001

최근 인터넷은 전 세계적으로 대중화되고 다양한 분야에서 많이 응용되고 있다. 특히 인터넷을 이용한 Telerobot 시스템의 연구가 활발히 진행되면서, 인터넷상에서의 네트워크 상태나 대역폭에 따른 시간지연 문제가 중요한 이슈가 되고 있다. 이는 조작자가 의도하는 데로 이동로봇을 제어하기 위해 반드시 해결되어야할 문제이다. 따라서 본 논문에서는 원격지의 조작자가 지시하는 데로의 원활한 주행을 위하여 이동로봇에 전송되는 명령에 신간정보를 함께 보냄으로써, 이를 수신한 이동로봇이 지연시간을 계산하여 시간지연에 따른 경로오차를 보상하거나, 이전의 경로를 이용하여 앞으로의 경로를 예측함으로써 이동로봇이 적절한 경로를 주행할 수 있도록 함을 목적으로 한다.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.1
• /
• pp.30-35
• /
• 2008

In this paper, the application of power Quality monitoring based on Sampled Value(SV) which is introduced in the IEC61850 International Standard for substation communication are discussed. Firstly, while Merging Unit(MU) is designed as a process level device transmitting sensor data, the practical problems such as time delay compensation and optical fiber communication are encountered. Secondly, the Sampled Value message which is proper to a power quality monitoring system is presented. Because the power quality monitoring system requests less time-critical service compared to protection and control applications, the Sampled Value service message structure is introduced to improve efficiency. Lastly, the power quality monitoring server having various power quality analysis functions is suggested to verify the performance of Merging Unit With the diverse experiments, it is proved that the process bus distributed solution is flexible and economic for the power quality monitoring.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.2
• /
• pp.790-799
• /
• 2018

This paper proposes a single-phase unified power quality conditioner (S-UPQC) for maintaining power quality issues in a microgrid. The S-UPQC can compensate the voltage and current harmonics, voltage sag, and swell as a dynamic voltage restorer (DVR), regardless of variations in the grid frequency. Odd harmonics are treated as even-order harmonics in a rotating frame to implement the harmonic compensators with only one repetitive controller (RC) without any harmonic extractor. The dynamic performance is improved and the delay time is reduced in the RC. The S-UPQC control scheme is designed to maintain accurate and stable operation under deviations of the grid frequency by using the Lagrange interpolation-based finite-impulse-response (LIFIR) filter approximation method. The proposed control schemes were validated through a simulation and experiment.

• 한국HCI학회:학술대회논문집
• /
• 2008.02c
• /
• pp.12-18
• /
• 2008

This paper introduces the existing network-adaptive transport techniques for haptic-enhanced system. First we classify haptic-based network systems according to the communication architecture and data type. Then the existing studies concerning network QoS requirements for haptic-based network system are depicted. Finally, the survey of network-adaptive transport schemes is introduced devided into three key issues: delay and jitter compensation, error control, and transmission control.

• Smart Structures and Systems
• /
• v.12 no.2
• /
• pp.157-179
• /
• 2013

We present an approach, based on the state dependent Riccati equation, for designing non-collocated seismic response control strategies for buildings accounting for physical constraints, with particular attention to force saturation. We consider both cases of active control using general actuators and semi-active control using magnetorheological dampers. The formulation includes multi control devices, acceleration feedback and time delay compensation. In the active case, the proposed approach is a generalization of the classic linear quadratic regulator, while, in the semi-active case, it represents a novel generalization of the well-established modified clipped optimal approach. As discussed in the paper, the main advantage of the proposed approach with respect to existing strategies is that it allows to naturally handle a broad class of non-linearities as well as different types of control constraints, not limited to force saturation but also including, for instance, displacement limitations. Numerical results on a typical building benchmark problem demonstrate that these additional features are achieved with essentially the same control effectiveness of existing saturation control strategies.