• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.825-829
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• 2005

This paper presents an approach for designing a fuzzy logic-based adaptive SVC damping In controller for damping low frequency power oscillations. Power systems are often subject to low Frequency electro-mechanical oscillations resulting from electrical disturbances. Generally, power system stabilizers are designed to provide damping against this kind of oscillations. Another means to achieve damping is to design supplementary damping controllers that are equipped with SVC. Various approaches are available for designing such controllers, many of which are based on the concepts of damping torque and others which treat the damping controller design as a generic control problem and apply various control theories on it. In our proposed approach, linear optimal controllers are designed and then a fuzzy logic tuning mechanism is constructed to generate a single control signal. The controller uses the system operating condition and a fuzzy logic signal tuner to blend the control signals generated by two linear controllers, which are designed using an optimal control method. First, we design damping controllers for the two extreme conditions; the control action for intermediate conditions is determined by the fuzzy logic tuner. The more the operating condition belongs to one of the two fuzzy sets, the stronger the contribution of the control signal from that set in the output signal. Simulation studies done on a one-machine infinite-bus and a four-machine two-area test system, show that the proposed fuzzy adaptive damping SVC controller effectively enhances the damping of low frequency oscillations.

• Smart Structures and Systems
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• v.3 no.4
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• pp.405-422
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• 2007

A new hybrid damping technique for vibration reduction in flexible structures, wherein a combination of layers of hard passive damping alloys and active (smart) magnetostrictive material is used to reduce vibrations, is proposed. While most conventional vibration control treatments are based exclusively on either passive or active based systems, this technique aims to combine the advantages of these systems and simultaneously, to overcome the inherent disadvantages in the individual systems. Two types of combined damping systems are idealized and studied here, viz., the Noninteractive system and the Interactive system. Frequency domain studies are carried out to investigate their performance. Finite element simulations using previously developed smart beam elements are carried out on typical metallic and laminated composite cantilever beams treated with hybrid damping. The influence of various parameters like excitation levels, frequency (mode) and control gain on the damping performance is investigated. It is shown that the proposed system could be used effectively to dampen the structural vibration over a wide frequency range. The interaction between the active and passive damping layers is brought out by a comparative study of the combined systems. Illustrative comparisons with 'only passive' and 'only active' damping schemes are also made. The influence and the mode dependence of control gain in a hybrid system is clearly illustrated. This study also demonstrates the significance and the exploitation of strain dependency of passive damping on the overall damping of the hybrid system. Further, the influence of the depthwise location of damping layers in laminated structures is also investigated.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.1-6
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• 2008

The performance of shock absorber is directly related to the car behavior and performance, both for handling and comfort. Most of compact car are assembled the passive shock absorber for cost effect but some of compact driver want better performance of shock absorber than standard parts. Therefore, they want the semi-active suspension control system instead of standard damper system. But they only can change the mechanical damping control shock absorber at A/S market. The mechanical damping control shack absorber can not vary the damping force in driving condition so they do not satisfy the mechanical damping control shock absorber system. In this study, electrically damping force controlled shock absorber system is developed based on the mechanical damping force control damper system. This system can vary damping force by switch on dashboard in driving condition. And, this system can satisfy the requirement of tuning market. Therefore, it is expected the system to show the engineering capability of korean damper company and to increase export market share to oversea damper market.

• Current Applied Physics
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• v.18 no.11
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• pp.1388-1392
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• 2018

Metal thin films are used widely to solve the vibration problem. However, damping mechanism is still not clear, which limits the further improvement of the damping properties for film and the development of multi-functional damping coating. In this paper, Damping microscopic mechanism of porous metal films was investigated at both macroscopically and microscopically mixed levels. Molecular dynamics simulation method was used to model and simulate the loading-unloading numerical experiment on the micro-pore and vacancy model to get the stress-strain curve and the microstructure diagram of different defects. And damping factor was calculated by the stress-strain curve. The results show that dislocations and new vacancies appear in the micro-pores when metal film is stretched. The energetic consumption from the motion of dislocation is the main reason for the damping properties of materials. Micro-mechanism of damping properties is discussed with the results of in-situ experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.8
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• pp.651-657
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• 2003

A new mechanical-electrical hybrid passive damping treatment is proposed to improve the performance of structural vibration control. The proposed hybrid passive damping system consists of a constrained layer damping treatment and a shunt circuit. In a passive mechanical constrained layer damping, a viscoelastic material damping layer is used to control the structural vibration modes in high frequency range. The passive electrical damping is designed for targeting the nitration amplitude in the low frequency range. The governing equations of motion are derived through the Hamilton's principle. The obtained mathematical model Is validated experimentally. The presented theoretical and experimental techniques provide invaluable tools for controlling the multiple modes of a vibrating structure over a wide frequency band.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.427-430
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• 2002

The present parer outlines the system identification and vibration control performance of air traffic control tower of Yangyang international airport with tuned mass damper(TMD). From the free vibration test, natural frequency, damping ratio and mode shape of tower are obtained and these values are compared with the values from numerical analysis. In the vibration control test to evaluate the vibration control performance, equivalent damping ratio increased by tuned mass damper are obtained in case the TMD is operated as passive mode. Damping ratio of tower evaluated from free vibration test is about $1.0{\%}$. It is very low value than damping ratio recommended in general code. Damping ratio of passive mode is about $5{\%}$. These equivalent damping ratio increased by TMD is enough to enhance the serviceability of tower structure under wind load.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1589-1596
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• 2015

A novel control method of a three-phase PWM inverter with LC filter is proposed. The transfer function of LC filter is the same as that of 2nd order low pass filter(2nd LPF) which has a zero damping ratio. A simple method of implementing 2nd LPF with damping ratio is to add resistor to inductor or capacitor of LC filter. In an industrial application, it is not practical to adopt damping resistor because it results in losses being proportional to square of current flowing through resistor. Instead of using damping resistors, the proposed active damping control(ADC) utilizes all pass filter(APF) and considers inherent processing delay of digital controller. The overall transfer function of the proposed method is the same as a 2nd LPF and its damping ratio is also controllable via control variables. Detailed design and implementation of controller is also presented. Experiments are conducted with a 7.5kVA induction motor drive system controlled by PWM converter and inverter. Test waveforms are also presented to verify the proposed LC filter control algorithm.

• Wind and Structures
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• v.11 no.6
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• pp.497-512
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• 2008

In this paper, optimum methods of wind-induced vibration control of high-rise buildings are mainly studied. Two optimum methods, genetic algorithms (GA) method and Rayleigh damping method, are firstly employed and proposed to perform optimum study on wind-induced vibration control, six target functions are presented in GA method based on spectrum analysis. Structural optimum analysis programs are developed based on Matlab software to calculate wind-induced structural responses. A high-rise steel building with 20-storey is adopted and 22 kinds of control plans are employed to perform comparison analysis to validate the feasibility and validity of the optimum methods considered. The results show that the distributions of damping coefficients along structural height for mass proportional damping (MPD) systems and stiffness proportional damping (SPD) systems are entirely opposite. Damping systems of MPD and GAMPD (genetic algorithms and mass proportional damping) have the best performance of reducing structural wind-induced vibration response and are superior to other damping systems. Standard deviations of structural responses are influenced greatly by different target functions and the influence is increasing slightly when higher modes are considered, as shown fully in section 5. Therefore, the influence of higher modes should be considered when strict requirement of wind-induced vibration comfort is needed for some special structures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.7
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• pp.261-266
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• 2001

The flexural vibration of laminated composite beams with active and passive constrained layer damping has been investigated to design a structure with maximum possible damping capacity. The equations of motion are derived fro flexural vibrations of symmetrical,. multi-layer laminated beams. The damping ratio and model damping of the first bending mode are calculated by means of iterative complex eigensolution method. The direct negative velocity feedback control is used for the active constrained layer damping. It is shown that the flexible laminated beam is more effective in the vibration control for both active and passive constrained layer damping. and this paper addresses a design strategy of laminated composite under flexural vibrations with constrained layer damping.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.293-296
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• 2005

This paper is concerned with the sweeping damping controller for beam. The active damping characteristics can be enhanced by moving the damper along the longitudinal axis. In this paper, the equation of motion for a beam including a sweeping damping controller is derived and its stability is proved by using Lyapunov stability theorem. It is found from the theoretical study that the sweeping damping controller can enhance the active damping characteristics, so that a single damper can suppress all the vibration modes of the beam. To demonstrate the concept of the sweeping damping control, the eddy current damper was applied to a cantilever, where the eddy current damping can move along the axis. The experimental result shows that the sweeping eddy current damper Is an effective device for vibration suppression.