• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.963-966
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• 2005

Model updating method is known to the area to correct finite element models by the results of the experimental modal analysis. Most common methods in model updating depend on a parametric model of the structure. In this case, the number of parameters is normally smaller than that of modal data obtained from an experiment. In order to overcome this limitation, many researchers are trying to get modal data as many as possible to date. 1 want to name this method multiple modified-system generation method. These Methods consist of direct system modification method and feedback controller method. The direct system modification Is to add a mass or stiffness on the original structure or perturb the boundary conditions. The feedback controller method is to make the closed food system with sensor and actuator so as to get the closed loop modal data. In this paper, we need to focus on the feedback controller method because of its simplicity. Several methods related the feedback controller methods are virtual passive controller (VPC) sensitivity enhancement controller (SEC) and mode decoupling controller (MDC). Among them, we will apply MDC to the model updating problem. MDC has various advantages compared with other controllers, such as VPC and SEC. To begin with, only the target mode can be changed without changing modal property of non-target modes. In addition, it is possible to fix any modes if the number of sensors is equal to that of the system modes. Finally, the required control power to achieve desired change of target mode is always lower than those of other methods such as VPC. However, MDC can make the closed loop system unstable when using incomplete modal data. So we need to take action to avoid undesirable instability from incomplete modal data. In this paper, we address the method to design the unique and robust MDD obtained from incomplete modal data. The associated simulation will be Incorporated to demonstrate the usefulness of this method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1334-1337
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• 2006

System identification is the field of modeling dynamic systems from experimental data. As a modeling technique, we can mention finite element method (FEM). In addition, we are able to measure modal data as the experimental data. The system can be generally categorized into a gray box and black box. In the gray box, we know mathematical model of a system, but we don't know structural parameters exactly, so we need to estimate structural parameters. In the black box, we don't know a system completely, so we need to identify system from nothing. To date, various system identification methods have been developed. Among them, we introduce system realization theory which uses Hankel matrix and Eigensystem Realization Algorithm (ERA) that enable us to identify modal parameters from noisy measurement data. Although we obtain noise-free data, however, we are likely to face difficulties in identifying a structure with hidden modes. Hidden modes can be occurred when the input or output position comes to a nodal point. If we change a system using a mode decoupling controller, the hidden modes can be revealed. Because we know the perturbation quantities in a closed loop system with the controller, we can realize an original system by subtracting perturbation quantities from the closed loop system. In this paper, we propose a novel method to identify a structure with hidden modes using the mode decoupling controller and the associated example is given for illustration.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.864-869
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• 2004

A novel concept of feedback loop design for modal test and model updating is proposed. This method uses the closed -loop natural frequency information for parameter modification to overcome the problems associated with the conventional method employing the modal sensitivity matrix. To obtain new modal information from closed-loop system, controllers should be effective in changing modal data while guaranteeing the stability of closed-loop system. It is very hard to guarantee the stability of the closed-loop system with non-collocated sensor and actuator set. Ill this research, we proposed a controller called mode-decoupling controller that can change a target mode as much as the designer wants guaranteeing the stability of closed-loop system. This controller can be computed just using measured open-loop modeshape matrix. A simulation based on time domain input/output data is performed to check the feasibility of proposed control method.

• 한국소음진동공학회논문집
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• 제14권10호
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• pp.955-961
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• 2004

A novel concept of feedback loop design for modal test and model updating is proposed. This method uses the closed-loop natural frequency information for parameter modification to overcome the problems associated with the conventional method employing the modal sensitivity matrix. To obtain new modal information from closed-loop system, controllers should be effective in changing modal data while guaranteeing the stability of closed-loop system. But it is very hard to guarantee the stability of the closed-loop system with non-collocated sensor and actuator set. In this research, we proposed a controller called mode-decoupling controller that can change a target mode as much as the designer wants guaranteeing the stability of closed-loop system. This controller can be computed Just using measured open-loop modeshape matrix. A simulation based on time domain input/output data is performed to check the feasibility of proposed control method.

• Journal of Power Electronics
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• 제19권4호
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• pp.881-893
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• 2019

This paper proposes a practical sliding-mode controller design for shaping the impedances of cascaded boost-converter power decoupling circuits for reducing the second order harmonic ripple in photovoltaic (PV) current. The cascaded double-boost converter, when used as power decoupling circuit, has some advantages in terms of a high step-up voltage-ratio, a small number of switches and a better efficiency when compared to conventional topologies. From these features, it can be seen that this topology is suitable for residential (PV) rooftop systems. However, a robust controller design capable of rejecting double frequency inverter ripple from passing to the (PV) source is a challenge. The design constraints are related to the principle of the impedance-shaping technique to maximize the output impedance of the input-side boost converter, to block the double frequency PV current ripple component, and to prevent it from passing to the source without degrading the system dynamic responses. The design has a small recovery time in the presence of transients with a low overshoot or undershoot. Moreover, the proposed controller ensures that the ripple component swings freely within a voltage-gap between the (PV) and the DC-link voltages by the small capacitance of the auxiliary DC-link for electrolytic-capacitor elimination. The second boost controls the main DC-link voltage tightly within a satisfactory ripple range. The inverter controller performs maximum power point tracking (MPPT) for the input voltage source using ripple correlation control (RCC). The robustness of the proposed control was verified by varying system parameters under different load conditions. Finally, the proposed controller was verified by simulation and experimental results.

• 전력전자학회논문지
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• 제23권6호
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• pp.389-396
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• 2018

This study proposes a control method using a repetitive controller for a boost-type PFC rectifier with an APD circuit structure to improve the current distortion caused by DCM condition. Conventional proportional integral controllers have bandwidth limitations in DCM conditions. The performance improvement of the APD controller in the DCM region is verified through simulations and experiments on the compensation of harmonics by the repetitive controller.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.677-687
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• 2018

This paper presents a novel power decoupling control scheme with the bidirectional buck-boost converter for primary-side regulation photovoltaic (PV) micro-inverter. With the proposed power decoupling control scheme, small-capacitance film capacitors are used to overcome the life-span and reliability limitations of the large-capacitance electrolytic capacitors. Then, an improved flyback PV inverter is employed in continuous conduction mode with primary-side regulation for the PV power conditioning. The proposed power-decoupling controller shares the reference for primary side current regulation of the flyback PV inverter. The decoupling controller shapes the input current of the bidirectional buck-boost converter. The shared reference eliminates the phase-delay between the input current to the bidirectional buck-boost converter and the double frequency current at the PV primary current. The elimination of the phase-delay in dynamic response enhances the ripple rejection capability of the power decoupling buck-boost converter even with small film capacitor. With proposed power decoupling control scheme, the additional advantage of the primary-side regulation of flyback PV inverter is that there is no need to have an extra current sensor for obtaining the ripplecurrent reference of the decoupling current-controller of the power-decoupling buck-boost converter. Therefore, the proposed power decoupling control scheme is cost-effective as well as the size benefit. A new transient analysis is carried out which includes the source voltage dynamics instead of considering the source voltage as a pure voltage source. For verification of the proposed control scheme, simulation and experimental results are presented.

• 한국정보통신학회논문지
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• 제13권3호
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• pp.514-521
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• 2009

영구자석 매입형 동기 전동기(IPM : Interior-mounted Permanent Magnet Motor)의 전류제어는 릴럭턴스에 의존하는 최대토크 특성 때문에 표면부착형 동기전동기(SPM : Surface-mounted Permanent Magnet Motor)보다 더 복잡하다. 그러므로 고성능 토크제어를 위해서는 d축 전류와 q축 전류의 상태 디커플링이 필요하다. 하지만 상태들 사이에 영향을 미치는 인덕턴스의 변화 때문에 상태 디커플링이 어렵다. 그러므로 이 변화에 대처할 수 있는 상태 디커플링 방법의 개발이 필요하며 이를 이용한 전류의 독립제어가 필요하다. 본 논문에서는 IPM모터 에 대하여 가상 상태를 갖는 슬라이딩 모드 제어를 이용하여 상태 디커플링이 가능한 접근법을 제안한다. 제안된 슬라이딩 평면은 의란과 불확실성이 존재하더라도 PI 전류 제어기에 의해서 제어되는 공칭 시스템의 동특성을 가질 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제29권8호
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• pp.842-848
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• 2005

The decoupling control using state feedback was once intensively studied during 1960's by many researchers. However, this control scheme was sensitive to the disturbance and Parameter variations. SMC(sliding mode control) is known as a robust control methodology to overcome such a disturbance. In this paper. the decoupling control by means of SM(sliding mode) for a trajectory control of a two-degrees-of- freedom manipulator was discussed. The position and velocity of manipulator tip were adopted to compose a nonlinear error functions. The reference inputs of the controller can be decided by switching function combined with the desired position and velocity. Simulation result is provided to verify the effectiveness of the proposed control scheme.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.702-707
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• 2004

In this paper, we proposed the decoupling VSS controllers for a trajectory control of a two degrees of freedom SCARA type manipulator. We decoupled the position and velocity of a manipulator tip by using a nonlinear error functions. The reference inputs of the controller can be decided directly from the desired position and velocity. Simulation result is provided to verity the effectiveness of the proposed control scheme.