• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.16-19
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• 1994

This paper describes a design method of compensators for decentralized control systems. Decentralized control problem is convenient to design multi-variable control systems and formulated as a series of independent designs. The proposed design method is composed of some steps, which is sequentially to close loop of the system diagonalized by regarding interactive subsystem as perturbation for current loop. So, on the basis of H$_{\infty}$ control theory, decentralized controllers are designed considering robust stability for diagonal systems with perturbations. A numerical example shows that the proposed design method is effective for multivariable control systems..

• Ocean Systems Engineering
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• 제10권2호
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• pp.227-241
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• 2020

This paper deals with the problem of the global stabilization for a class of tension leg platform (TLP) nonlinear control systems. Problem and objective: Based on the relaxed method, the chaotic system can be stabilized by regulating appropriately the parameters of dither. Scope and method: If the frequency of dither is high enough, the trajectory of the closed-loop dithered chaotic system and that of its corresponding model-the closed-loop fuzzy relaxed system can be made as close as desired. Results and conclusion: The behavior of the closed-loop dithered chaotic system can be rigorously predicted by establishing that of the closed-loop fuzzy relaxed system.

• 제어로봇시스템학회논문지
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• 제10권10호
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• pp.956-960
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• 2004

The Vehicle Dynamic Simulator(VDS) is a key equipment of the performance verification of attitude control subsystem and it simulates the real dynamic environment that spacecraft undergoes during mission operation. All the software models and hardware interfaces necessary for the closed-loop simulation of the spacecraft dynamics are implemented. Using VDS, KOMPAT-2 attitude control logic functions and performance was verified. In this paper, the hardware and software configurations of KOMPSAT-2 VDS was described briefly and the information flow and exchanges between software models and actual hardwares during close loop simulation was described in the systematic point of view.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.54.6-54
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• 2002

1. Introduction 2. The Netwoked Control System Description 2.1 A close-loop system with the network induced delay 2.2 Discretization and State Augmentation of NCS 3. Delay-dependent H_infinity Controller Design for NCS 4. Numerical Example 5. Conclusion

• Journal of Power Electronics
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• 제13권3호
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• pp.369-380
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• 2013

Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ($V_d$, $V_q$) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.

• Journal of Power Electronics
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• 제10권5호
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• pp.518-527
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• 2010

This paper presents a new technique for directly designing a linear digital controller for a single-phase pulse width modulation (PWM) converter systems, based on closed-loop identification. The design procedure consists of three steps. First, obtain a digital current controller for the inner loop system by using the error space approach, so that the power factor of the supply is close to one. The outer loop is composed of a voltage controller, a current control loop including a current controller, a PWM converter, and a capacitor. Then, all the components, except the voltage controller, are identified by a discrete-time equivalent linear model, using the closed-loop output error (CLOE) method. Based on this equivalent model, a proper digital voltage controller is then directly designed. It is shown through PSim simulations and experimental results that the proposed method is useful for the practical design of PWM converter controllers.

• 한국멀티미디어학회논문지
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• 제14권3호
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• pp.414-422
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• 2011

본 연구는 얇은 유전체기판 위에 프린트 패턴으로 구현하는 상/하 대칭 루프안테나에 관한 것으로서, 유전체기판 상/하에 대칭으로 루프안테나용 동박패턴을 제작하여 기판의 상/하에 프린트된 루프패턴 간에서 방사되는 전자계가 서로 충돌하지 않게 방사되는 위상제어형 상/하 대칭 루프안테나에 관한 것이다. 이 방법으로 상/하에 프린트된 각 루프코일이 서로 동위상으로 보완적으로 배치되어 전자계가 원만하게 방사되어, 방사 손실이 없고 방사 효율이 뛰어나게 된다. 앓은 유전체기판의 상/하에 프린트하여 안테나를 구현함으로 연해 경박/소형화가 가능해지며, 이로 인하여 크기 $40mm{\times}6mm$ 이하의 사이즈에, 두께 0.2mm 이하의 박막의 유전체가판에 제 3세대 휴대폰대역인 WCDMA 안테나를 구현하여 액티브 시험에서 평균게인 -3dBi 이상 방사효율 50~70% 정도의 안테나특성이 얻어졌으며, 상용되는 이동형 멀티미디어단말기에 부착하여 액티브 시험결과 평균게인 -4dBi, 송/수신 효율이 43% 얻어졌다.

• Journal of Power Electronics
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• 제15권6호
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• pp.1456-1467
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• 2015

This paper presents a novel close-loop control scheme based on small signal modeling and weighted composite voltage feedback for a three-phase input and single-phase output Matrix Converter (3-1MC). A small non-polar capacitor is employed as the decoupling unit. The composite voltage weighted by the load voltage and the decoupling unit voltage is used as the feedback value for the voltage controller. Together with the current loop, the dual-loop control is implemented in the 3-1MC. In this paper, the weighted composite voltage expression is derived based on the sinusoidal pulse-width modulation (SPWM) strategy. The switch functions of the 3-1MC are deduced, and the average signal model and small signal model are built. Furthermore, the stability and dynamic performance of the 3-1MC are studied, and simulation and experiment studies are executed. The results show that the control method is effective and feasible. They also show that the design is reasonable and that the operating performance of the 3-1MC is good.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.565-568
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• 1995

This paper presents the position control of a closed-loop cylinder system using ER(electro-rheological)valve actuators. Following the field-dependent pressure analysis of the ER valve actuators on the basis of Bingham model of ER fluids, a 3 d.o.f. close-loop sylinder system having the heave, roll and pitch motions is proposed. The governing equations of motion are derived using Lagrange's equation, and a control model is established by considering system uncertain parameters such as load conditions. A sliding mode controller which has inherent robustness to system uncertainties is adopted to achieve robust tracking control performance. Tracking control results for sinusoidal trajectory were presented in order to demonstrate the effectiveness of the proposed control system.

• 한국정보통신학회논문지
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• 제4권5호
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• pp.1117-1125
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• 2000

벅 컨버터 회로 평균모델를 이용하고 한주기 응답 기법을 적용한 전류모드 PWM 기법을 제안하였다. 이 제어기는 비선형 PWM 제어기로 스위칭 변수와 응답 기준과의 오차를 각 주기에서 0이 되도록 구현하였다. 그 결과, 시스템 전달함수는 폐루프 극점의 함수가 되어 설계가 용이하며 폐루프 특성이 향상되었다. 이 제어기에서 인덕터 전류의 상태 변수를 구현하기 위하여 전류모드를 이용하여 컨버터를 제어하였다. 제안한 PWM제어는 인덕터 전류 센서를 생략할 수 있으며 잡음 특성, 동특성이 기존 전류 모드 제어기에 비하여 많은 장점을 갖는다. 시뮬레이션 및 실험을 통하여 타당성을 입증하였다.