• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.556-557
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• 2014

This paper presents an artificial intelligence - Deep Belief Network (DBN) gain-scheduling adaptive PI controller scheme for dual active bridge (DAB) converter. The PI gains are allowed to vary within a predetermined range and therefore eliminate the problems faced by the conventional PI controller. The performance of the proposed controller is simulated and compared with the conventional fixed PI controller under various conditions. The experimental prototype of the DAB converter is implemented using a digital signal processor of TMS320F28335 manufactured by Texas Instrument to examine and to evaluate the performance criteria of the proposed controller. Simulation and experimental results show improvements in transient as well as steady state responses of the proposed controller over the conventional fixed PI controller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.761-764
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• 1995

This paper demonstrates the feasibility of utilizing Shape Memory Alloy(SMA) actuators in controlling the motion of micro active catherer. The dynamic behavior of SMA is obtained by several experiments for the design of the controller. Two different type of structures which realize catheter are proposed. Each prototype of micro active catherer is fabricated, and its control performance which used the designed controller is investigated. The results obtained show the potential of the SMA as viable means for actuating the micro active catheter.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1176-1182
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• 2010

Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mount have been developed to cope with such specifications. The active-type engine mount consists of sensor, actuator and controller where a control algorithm is implemented. The performance of the active engine mount depends on the control algorithm if the sensor and actuator satisfies the specification. The control algorithm should be able to suppress persistent vibrations caused by the engine which are related to engine revolution. In this study, three control algorithms are considered for suppressing persistent vibrations, which are the positive position feedback control algorithm, the strain-rate feedback control algorithm, and the modified higher harmonic control algorithm. Experimental results show that all the control algorithms considered in this study are effective in suppressing resonant vibrations but the modified higher harmonic controller is the most effective controller for non-resonant vibrations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.193-200
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• 2003

This paper presents a hybrid (i.e., integrated passive-active) system for seismic response control of a cable-stayed bridge. Because multiple control devices are operating, a hybrid control system could alleviate some of the restrictions and limitations that exist when each system is acting alone. Lead rubber bearings are used as passive control devices to reduce the earthquake-induced forces in the bridge and hydraulic actuators are used as active control devices to further reduce the bridge responses, especially deck displacements. In the proposed hybrid control system, a linear quadratic Gaussian control algorithm is adopted as a primary controller. In addition, a secondary bang-bang type (i.e., on-off type) controller according to the responses of lead rubber bearings is considered to increase the controller robustness. Numerical simulation results show that control performances of the hybrid control system are superior to those of the passive control system and slightly better than those of the fully active control system. Furthermore, it is verified that the hybrid control system with a bang-bang type controller is more robust for stiffness perturbation than the active controller with μ-synthesis method and there are no signs of instability in the overall system whereas the active control system with linear quadratic Gaussian algorithm shows instabilities in the perturbed system. Therefore, the proposed hybrid protective system could effectively be used to seismically excited cable-stayed bridges.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.1
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• pp.30-41
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• 2004

This paper is concerned with the active vibration control of flexible cantilever beam system using electromagnetic farce actuator. The main objective of this paper is to propose the control algorithms and to implement the experimental setups for active vibration control. Dynamic equations of the electromagnetic actuator and the beam are combined to find the transfer function from the electromagnetic actuator to the laser sensor. The final transfer function is determined by considering only the first and second modes, and experiments confirm that this model works well. Several control algorithms are proposed and implemented on the experimental setups to show their efficacy. These include a PID control design, an optimal H$_2$ control design, and a fuzzy PID control design. Effectiveness and performance of the designed controller were verified by both simulation and experiment results.

• 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.

• Journal of KSNVE
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• v.9 no.1
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• pp.33-41
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• 1999

This paper presents a method of actively controlling the interior noise by a trim panel with hybrid feedforward-feedback control loop. The control technique is designed to minimize the vibration of panel whose motion is limited to that of a piston (out-of-plane motion). The hybrid controller consists of an adaptive feedforward controller in conjunction with a linear quadratic Gaussian (LQG) feedback controller. In order to maintain control performance of both persistent and transient disturbances, the feedback loop speeds up the adaptation rate of feedforward controller by improving damping capacity of secondary plant related with the adaptation rule. Numerical simulation and experimental result indicate that the hybrid controller is a more effective method for reducing the vibration of the panel (and therefore the interior noise) compared to using feedforward controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.148-152
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• 2003

This paper is concerned with the digital implementation of the active vibration suppression controller. The digital controllers are often implemented on the DSP board, which is very fast but expensive. There are many low-cost micro-controllers in the market but the feasibility of such micro-controllers for the active vibration suppression has never been conducted. In this study, we selected PIC 16F877 as a proper micro-controller for the digital implementation of the PPF controller. The circuit diagrams are explained in detail. Experimental results show that the low-cost micro-controller can be used as the active vibration controller.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.313-320
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• 2002

A new semi-active control strategy for seismic response reduction using a neuro-controller and a magnetorheological (MR) fluid damper is proposed. The proposed control system consists of the improved neuro-controller and the bang-bang-type controller. The improved neuro-controller, which was developed by employing the training algorithm based on a cost function and the sensitivity evaluation algorithm replacing an emulator neural network, produces the desired active control force, and then the bang-bang-type controller causes the MR fluid damper to generate the desired control force, so long as this force is dissipative. In numerical simulation, a three-story building structure is semi-actively controlled by the trained neural network under the historical earthquake records. The simulation results show that the proposed semi-active neuro-control algorithm is quite effective to reduce seismic responses. In addition, the semi-active control system using MR fluid dampers has many attractive features, such as the bounded-input, bounded-output stability and small energy requirements. The results of this investigation, therefore, indicate that the proposed semi-active neuro-control strategy using MR fluid dampers could be effectively used for control of seismically excited structures.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1438-1449
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• 2018

The importance of power system stability has been emphasized with an increase of wind energy penetration in the power system. Accordingly, the guarantee on various control capabilities, including active and reactive power control of wind farms, was regarded as the most important aspect for the connection to the grid. To control the wind farm active power, the wind farm controller was introduced. The wind farm controller decides the power set points for each wind turbine generating unit and each wind turbine generating unit controls its power according to the set points from the wind farm controller. Therefore, co-relationship between wind farm controller and wind turbine controllers are significantly important. This paper proposes some control methods of wind farm active power control based on modified wind turbine control for power system stability and structures to connect wind turbine controllers to wind farm controller. Besides, this paper contributes to development of control algorithm considering not only electrical components but also mechanical components. The proposed contributions were verified by full simulation including power electronics and turbulent wind speed. The scenario refers to the active power control regulations of the Eltra and Elkraft system in Denmark.