• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.21-26
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• 2007

Output voltage waves of a DC/AC inverter system are likely to be distorted if variable loads e.g. motors or rectifiers exist in the output terminal. This paper designs a disturbance observer-based PI-controller for a single-phase inverter system that is robust against load changes. In this Paper, we regard the output voltage changes due to various loads as disturbances of the control system. Then we design a disturbance observer for estimation of the disturbances caused by the load current and any other error sources (such as parameter uncertainties and model mismatches etc.). In order to test the performance of the proposed control law, simulation studies are carried out for a single-phase inverter system using SimPowerSystem of Matlab Simuink. Compared to a simple PI-control, the disturbance observer-based controller shows enhanced performance in transient responses for step load changes.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.129-136
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• 2009

A motor cylinder is widely used as an apparatus for transportation of a small scale load. It is, however, difficult for only one motor cylinder to transfer a large scale load such as a weir. The large scale load is transferred by two motor cylinders which are mounted on right and left of load itself. In this case, the displacement difference generated between two motor cylinders, namely, the synchronous error has a bad influence on the transportation. In this study, a synchronous control system is designed to restrain synchronous error caused by skew disturbance. The control system is composed of two disturbance observers and one synchronous controller. Each disturbance observer is designed to restrain the skew disturbance. And the synchronous controller is designed to achieve stable and accurate synchronization. Finally, the simulation results show that the designed control system is effective for the skew disturbance which lead to synchronous error.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.51-52
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• 2015

분산전원을 계통에 연계하여 운용하는 경우 계통연계 인버터가 사용되며 계통에 주입되는 유효전력과 무효전력의 크기를 조절하기 위해 인버터의 출력전류를 제어하게 된다. 그러나 계통전압이 불평형 상태이거나 계통 임피던스에 변동이 있을 경우 계통연계 인버터의 출력전류 제어 성능이 떨어지는 문제가 발생한다. 본 논문에서는 계통전압의 불평형 상태와 계통 임피던스 변동에 강인한 계통연계 인버터의 새로운 전류제어 기법을 제안한다. 제안된 기법은 외란관측기 기반 제어기를 사용하여 계통전압의 불평형 혹은 계통 임피던스 변화와 같은 외란의 영향을 보상한다. 제안된 기법의 강인성과 성능이 시뮬레이션을 통해 입증된다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1991.10a
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• pp.69-74
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• 1991

본 논문은 슬라이딩 모드 제어 기법을 이용한 직류 전동기의 디지탈 속도 제어기에 관한 연구이다. 또한 연속 시스템에 적용하던 슬라이딩 모드 제어기법을 이산 시스템에 사용할 수 있도록 해석하고, 실험하였다. 슬라이딩 모드 제어기에서 발생되는 채터링(CHATTERING) 현상을 감소시키기 위해 스위칭 주파수를 높이고, 샘플링 주기를 최대한 줄였으며 제어기 출력에 필터를 도입하였다. 또한, 스위칭 지연과 외란에 대한 보상도 고려하였으며 슬라이딩 모드 제어기를 마이크로 프로세서로 구성하였다. 전력 소비를 줄이기 위해 LIMITED UNIPOLAR 모드에서 직류 전동기를 구동하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.508-519
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• 2018

This paper concerns on stabilization control of a gyro-stabilized 2-axes gimbal system which is mounted on a moving vehicles such as automobiles, armored vehicles, ships, flying vehicles, etc. A target image acquisition system is attached on the inner gimbal, and the gimbal systems are required to retain high stabilization accuracy in the absolute coordinate in order to provide fine target image while vehicle is moving. The stabilization control performance is hardly depended upon disturbance rejection ability of control, and disturbance feedforward compensation is effective because feedforward compensation reduce the amount of disturbance before the disturbance disturbs the systems. This paper suggests an experimental method which can estimate system parameters and disturbance torques by using 3-axes accelerometer mounted on the inner gimbal. Furthermore, a simple disturbance identification method which can be applied to any slanted base conditions has been suggested to identify mass unbalance vector and friction torques of each gimbal simultaneously. By using the estimated parameters, a feedforward compensation has been applied to the gyro-stabilized 2-axes gimbal system. The experimental results showed that the feedforward compensation based on the identification method suggested is effective to improve stabilization performances.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.4
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• pp.342-349
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• 1991

In this paper, a method is presented for designing a tracking and disturbance rejecting controller for a nonlinear control system in which approximate linearization is not applicable due to a s stiff nonlinearity. Only the measurable variables are used for the controller synthesis. The system is augmented by a compensator at the output side for the tracking and disturbance rejection. An output delayed feedback controller is designed for the augmented system without nonlinearity. Then the feedback parameters are adjusted by describing function method to overcome the limit cycle due to the nonlinearity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1597-1600
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• 2010

In this paper, a direct controller for nonlinear plants using a neural network is presented. The composed of the control input by using RBF neural networks and auxiliary input to compensate for effects of the approximation errors and disturbances. In the results, using this scheme, the output tracking error between the plant and the reference model can asymptotically converge to zero in the presence of bounded disturbances and approximation errors. Simulation results show that it is very effective and can realize a satisfactory control of the nonlinear system.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.74-79
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• 2002

Many control techniques have been proposed in order to improve the control performance in discrete-time domain control system. In control system using these techniques, the response-characteristic of system is dependent on the gains of the controller. Specially, There is a need to readjust the gain of controller when the response of system is changed by disturbance or load fluctuation. In this paper, I-PD controller and pre-compensator are designed by multilayer neural network. The gains of I-PD controller and pre-compensator are adjusted automatically by back propagation algorithm when the response characteristic of system is changed under a condition. Applying this control technique to the position control system using a DC servo motor as a driver, the control performance of controller is verified by the results of experiment.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.781-784
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• 2003

전원품질은 전원의 전압, 전류 및 주파수 성질을 나타낸다. 이러한 품질은 전력시스템에 대한 광범위한 전력외란이나 신호간섭 등에 의해 변화한다. 전력반도체에 의한 인버터, 컨버터, 제어기 등의 기술이 다양해지고 그 응용범위가 확대됨에 따라, 전원계통에 고조파에 의한 전력품질에 오염이 많이 발생한다. 전력전자기술이 응용하는 다양한 전력기기 들은 고조파 발생원이 되어, 전력에너지를 사용하는 모든 분야에서 전력품질 문제가 대두되었고 이 문제를 해결하기 위해 많은 노력을 기울여왔다. 본 논문에서는 무효전력보상과 고조파전류를 보상하기 위한 3상 능동전력필터의 모델을 제안한다. 제안된 시스템은 PWM 전압원 인버터의 구조로 되어있으며 두 가지의 특징을 가지고 있다. 첫째는 고정된 주파수로 동작한다는 점이며 둘째는 비선형 부하 하에서 부하전류의 무효성분을 검출 및 계산을 하지 않고 무효전력과 고조파전류를 보상할 수 있다는 점이다. 또한 시간영역에서 제어를 함으로써 간단하게 제어기를 설계할 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.58-66
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• 2009

In this paper, vector control to applied disturbance offset feedforward loop control for changing disturbances with various mechanical parameter is suggested. The proposed system estimate load torque based on induction motor torque using minimum diemension state observer. Because speed controller using state observer is used on condition of feedforward loop fur a torque, the robust speed control system realized. In this study, the proposed paper does to heighten reliability of system by presuming and use the speed by voltage and current that is detected without speed sensor. To prove the propriety of this paper, the various simulation carried out adequacy using a Matlab Simulink, and at the same time real system is made, using a ADMC300 digital signal processor, so it is proved. As the experimental result of embodying the system, the robust system is realized.