• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.79.2-79.2
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• 2011

플라이 휠 에너지 저장장치(Flywheel Energy Storage System: FESS)는 전기 에너지를 회전 운동 에너지로 저장하였다가 필요시 회전 운동에너지를 전기 에너지로 변환하여 재사용 가능한 에너지 저장장치 이다. 최근 전력 변환 기술의 발전으로 인하여 플라이휠 에너지 저장 장치의 에너지 입출력 속도가 빨라지고 대용량의 에너지를 저장할 수 있게 되었다. 본 논문에서는 이러한 플라이휠 에너지 저장 장치의 전력 입출력 특성을 이용하여 전력 시스템에서 발생하는 저주파 진동(Low frequency oscillation)을 억제하는 방안을 제시 하여 안정도를 향상 시키고자 하였다. 전력 시스템은 발전조건, 전송조건, 부하조건에 따라 동작 조건이 지속적으로 변하고 있다. 이러한 동작 환경 변화는 전력 시스템에 대한 수학적인 표현과 실제 전력계통간의 차이가 발생하기 때문에 정확한 제어 목적을 달성하기가 힘들다. 따라서 본 논문에서는 제어기 설계 단계에서 전력 계통의 불확실성을 고려할 수 있는 $H_{\infty}$ 제어 기법을 이용하여 플라이휠 에너지 저장장치를 위한 강인 제어기를 설계 하였다. 제안한 플라이휠 에너지 저장장치의 강인 제어기의 유용성을 입증하기 위하여 1기 무한대 모선에 적용한 결과를 비선형 시뮬레이션을 통하여 다양한 외란이 발생한 경우에 외란 억제 성능과 강인성에 대하여 고찰 하였으며, 제안한 방식이 기존의 전력계통 안정화 장치(Power system stabilizer: PSS) 보다 효율적이며 전력계통의 안정도 향상에 크게 기여함을 보이고자 하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.421-421
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• 2000

In this paper, robust two-degree-of-freedom controller for satellite antenna system which tracks reference signal is designed. Two-degree-of-freedom controller consists of a prefilter and a feedback controller to solve trade-off between robust stability and command response. The feedback controller is designed from specifications like stability, disturbance rejection and robustness via H$_{\infty}$ design technique. In the sequel, H$_2$ optimal prefilter is introduced to improve the command response. This suggests a two-step design, with different types of performance specifications at each stage. In practical problems, this may easily lead to a prefilter of unacceptably high order. In order to avoid high order prefilter we use a particular structure in which both the prefilter and the feedback controller share the same dynamics. H$_2$-prefilter technique proposed in this paper is verified by simulation.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1040-1043
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• 1996

The accuracy of the servo control in CNC system has a great influence on the duality of machine product. Tracking performance of the servo control is deteriorated mainly by the time delay of the servo system and the inertia of the work table or bed. Contouring errors occur in every interpolation steps by the effect of the tracking performance. In this paper, $H_{\infty}$ two-degree-of-freedom(TDF) controller is designed for improvement to improve the tracking performance. The designed controller is applied 3-axis machining center model and the cutting accuracy is simulated in case of corner cutting, circular and involute interpolation. Simulation results show that $H_{\infty}$ TDF controller designed in this paper has a good effect to improve tracking performance in CNC system.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1196-1201
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• 2004

H₂ controller is proposed for networked control systems with time-varying delay. The time-varying network delay is assumed to be unknown, but its lower and upper bounds are assumed to be known. The time-varying delay is treated like a parameter variation and robust control technique is used to deal with the time-varying delay. The proposed controller can be computed by solving linear matrix inequalities. Through numerical simulations, the proposed controller is verified.

• Journal of Drive and Control
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• v.5 no.2
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• pp.37-44
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• 2008

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.4
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• pp.191-200
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• 2000

In practical applications, we frequently encounter the actuator nonlinearity in control systems, and its representative nonlinearity is saturation. A controller designed without considering this saturation nonlinearity is often a source of degradation of performance. To treat the saturation nonlinearity more efficiently, we adopt the multiplicative decomposition and the additive decomposition. Based on these decompositions, we present two controller design methods in the LMI(Linear Matrix Inequality) form that guarantee the L2 gain, from the disturbance to the measured output, is less than or equal to a given value. Finally, we give two examples to show the applicability and usefulness of our results.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2589-2592
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• 2003

In this paper, a robust mixed H$_2$/H$\_$$\infty$/ output feedback control method is applied to the design of loop filter for PLL carrier phase tracking. The proposed method successfully copes with large S-curve slope uncertainty and a significant decision delay in the closed-loop that may exist In modern receivers due to a convolutional decoder or an equalizer. The objective is to design an output feedback controller which minimizes the H$_2$performance while satisfying the H$\_$$\infty$/ performance to guarantee the gain margin and phase margin for linear time invariant(LTI) polytopic uncertain systems. LMIs based approach is given to solve this problem. We can verify the H$\_$$\infty$/ performance satisfaction and minimize the phase detector error through the simulation result.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.112-112
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• 2000

The aim of this paper is to design a two degree-of-freedom H$_{\infty}$ controller for lateral control of the vehicle. The object of this controller is to track the centerline of the reference lane. The controller is splited into two parts, feedback and prefilter. The feedback part is for both robust stability and disturbance attenuation, while the prefilter is for improving the robust tracking properties of closed loop system. This paper is consist of preface, background theory, dynamics of vehicle, controller design and computer simulation.ter simulation.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.63-74
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• 1999

A sliding mode fuzzy control (SMFC) algorithm is presented for vibration of large structures. Rule-base of the fuzzy inference engine is constructed based on the sliding mode control, which is one of the nonlinear control algorithms. Fuzziness of the controller makes the control system robust against the uncertainties in the system parameters and the input excitation. Non-linearity of the control rule makes the controller more effective than linear controllers. Design procedure based on the present fuzzy control is more convenient than those of the conventional algorithms based on complex mathematical analysis, such as linear quadratic regulator and sliding mode control(SMC). Robustness of presented controller is illustrated by examining the loop transfer function. For verification of the present algorithm, a numerical study is carried out on the benchmark problem initiated by the ASCE Committee on Structural Control. To achieve a high level of realism, various aspects are considered such as actuator-structure interaction, modeling error, sensor noise, actuator time delay, precision of the A/D and D/A converters, magnitude of control force, and order of control model. Performance of the SMFC is examined in comparison with those of other control algorithms such as $H_{mixed 2/{\infty}}$ optimal polynomial control, neural networks control, and SMC, which were reported by other researchers. The results indicate that the present SMFC is an efficient and attractive control method, since the vibration responses of the structure can be reduced very effectively and the design procedure is simple and convenient.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.67-70
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• 1999

일반적으로 시설원예용 환경제어장치란 온실 내부 환경을 작물생육에 적합한 환경으로 조성시키기 위하여 원예시설에 부착된 환기창이나 냉난방장치, $CO_2$발생기, 양액제어장치 등을 통해 온도, 습도, $CO_2$, EC, pH 등의 각종 환경을 인위적으로 조절해 주는 장치라고 할 수 있다. 이러한 장치는 수동스위치 조작에서부터 전자제어, 컴퓨터에 의한 복합환경제어에 이르기까지 매우 다양한 제품이 생산 판매되고 있지만, 상호 제품간 호환성이 없으며, 성능에도 차이가 나는 것을 볼 수 있다. (중략)