• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.9-11
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• 2004

This paper presents a position control system for a linear induction motor(LIM) with cage-type secondary using direct thrust control(DTC). The position controller, that combines the merits of integral-proportional(IP) speed control, is designed for the LIM. The actual position of the LIM is defected by the linear scale the resolution of 100. Thrust correction coefficient due to the end effect of the LIM is utilized in estimating actual thrust. As a result, responses of the position, speed, thrust, and flux are shown.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1342-1348
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• 2009

DSTATCOM(distribution static compensator) is one of the custom power devices, and protects a distribution line from unbalanced and harmonic current caused by non-linear and unbalanced loads. Researches about DSTATCOM are mainly divided two parts, one is the calculation of compensated current and the other part is the current control. This paper proposes a proportional-resonant-repetitive current controller. Improved performance of instantaneous power compensation has been shown by simulations and experiments.

• 전기의세계
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• v.26 no.2
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• pp.99-103
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• 1977

The object of this work is to study an optimal design problem of the proportional load-frequency controller for the single-control area power system. The selfservice power station is still a popular means as a power supplying source on ships or in a certain manufacturing area. The power system of this kind can be formulated as a single control-area system and it attracts a certain academic interest in controlling the system frequency under disturbances. In this paper, the single control-area system is mathematically formulated as a linear, time-invariant system in state-space under certain assumptions. The optimal proportional control law and the realization of the controller in closed loop-version is studied so that the final system designed can attain the system frequency to the nominal stationing value after the small load-disturbance. As in general cases of optimal design problems, the performance index is assumed to be quadratic in states and the control effort, and the infinite time control process is assumed in this work. The final control system realized depicts certain improvements in case study; in stability, transient responses and in steady-state frequency deviation, even though the steady state error did not attain the zero value.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1721-1726
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• 2004

The studies of the half active suspension have been performed using various suspension models. In the early days, the modeling considered the inputs to the active suspension as the linear forces. Recently, due to the development of new control theory, the forces input to the half car active suspension system has been replaced by an actual input to the hydraulic actuators. Therefore, the dynamic of the active suspension system now consists of the dynamic of half car suspension system plus the dynamic of the hydraulic actuators. This paper proposed a new modeling technique in integrating both dynamic models. The proportional integral sliding mode control technique is utilized to control the hydraulically actuated of the half car active suspension system. The performance of the half car hydraulically actuated active suspension system is simulated with a bump input. The results show that the proposed modeling technique and the proportional integral sliding mode controller are improved the ride comfort and ride handling of the half car active suspension system.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.149-153
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• 2005

In the cardiovascular system, the waveform of the pulsatory blood pressure appears variously due to the cardiac impulse and compliance of blood vessels and arm tissue. We have constructed a blood pressure simulator to investigate effects of mechanical properties of artery walls and tissue on blood pressure measurements. The blood pressure simulator is designed to reproduce wave forms of blood pressure in human arteries. To minimize tracking error, we use a linear control valve, and adapt a hybrid control scheme which consists of a feedback controller and a feedforward controller. Any form of the pressure wave can be reproduced, changing function of the wave form in the computer connected to the simulator for control. From experiments, it has been shown that the simulator reproduces wave forms very well, and that the hybrid scheme adapted is superior to the feedback controller.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.6
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• pp.433-439
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• 2004

The Helicopter Simulator System is non-linear and complex. Futhermore, because of absence of its accurate mathematical model, it is difficult to control accurately its attitudes such as elevation angle and azimuth one. Therefore, we proposed a Hybrid GA-PID WAVENET(Genetic Algorithm Proportional Integral Derivative Wavelet Neural Network)control technique to control efficiently these angles. The proposed Hybrid GA-PID WAVENET is made through the following process. First, the WAVENET fundamental functions are defined. And their dilation and translation values are adjusted by GA to construct the optimal WAVENET controller. Secondly, the proportional, integral, and derivative gain coefficients of PR controller are tuned optimally. Finally, WAVENET controller which has a good transient characteristic and GA-PE controller which has a good steady state characteristic is adequately combined in hybrid type. Through the computer simulations, it is proved that the Hybrid GA-PE WAVENET control technique has a more excellent dynamic response than PID control technique and GA-PID one.

• 전기의세계
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• v.31 no.3
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• pp.209-217
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• 1982

This paper considers a finite spectrum assignment Problem for a functional retarded linear differential system with delays in control only. In this problem, by generalizing from an abstract linear system characterized by Semigroups on a Hilbert space to a finite dimensional linear system, we unify the relationship between a control-delayed system and its non-delayed system, and then by using the spectrum of the generator-decomposition of Semigroup, we try to get a feedback law which yields a finite spectrum of the closed-loop system, located at an arbitrarily preassigned sets of n points in the complex plane. The comparative examinations between the standard spectrum assignment method and the method of spectral projection for the feedback law which consists of proportional and finite interval terms over present and past values of control variables are also considered. The analysis is carry down to the elementary spectral projection level because, in spite of all the research efforts, so far there has been no significant attempt to obtain the feedback implementation directly from the abstract representation forms in the case of multivariables.

• International Journal of Ocean System Engineering
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• v.1 no.3
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• pp.120-135
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• 2011

This paper proposes a model based trajectory tracking control scheme for under-actuated underwater robotic vehicles. The difficulty in stabilizing a non-linear system using smooth static state feedback law means that the design of a feedback controller for an under-actuated system is somewhat challenging. A necessary condition for the asymptotic stability of an under-actuated vehicle about a single equilibrium is that its gravitational field has nonzero elements corresponding to non-actuated dynamics. To overcome this condition, we propose a continuous time-varying control law based on the direct estimation of vehicle dynamic variables such as inertia, damping and Coriolis & centripetal terms. This can work satisfactorily under commonly encountered uncertainties such as an ocean current and parameter variations. The proposed control law cancels the non-linearities in the vehicle dynamics by introducing non-linear elements in the input side. Knowledge of the bounds on uncertain terms is not required and it is conceptually simple and easy to implement. The controller parameter values are designed using the Taguchi robust design approach and the control law is verified analytically to be robust under uncertainties, including external disturbances and current. A comparison of the controller performance with that of a linear proportional-integral-derivative (PID) controller and sliding mode controller are also provided.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.54-61
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• 2015

In 3-phase 4-wire inverter, the unbalanced loads cause to increase the neutral current which brings the voltage deviation between the split dc-link capacitors to be larger. In order to solve this problem, a neutral leg is provided additively to the ordinary inverter circuit and the associated control methods are devised. This paper proposes a new neutral-leg controller based on a PR controller and shows relatively good performance even under unbalanced linear loads and nonlinear loads. The proposed control strategy illustrates its effectiveness under the various operating conditions through simulation works.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.567-575
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• 2016

This paper proposed the voltage control of stand-alone inverter for power quality improvement under unbalanced and non-linear load. The 3-phase DC-AC inverter controls CVCF(Constant Voltage Constant Frequency) and selective harmonic eliminate method in stand-alone mode by PR controller, and the stand-lone inverter supplies stable sinusoidal voltage to balanced, unbalanced and non-linear loads. The total harmonic distortion(THD) of line-to-line load voltage($V_{LL}$) is 1.2% in the balanced load. THD of $V_{LL}$ is reduced from 5.2% to 1.4% and 6.7% to 3.5%, respectively unbalanced and non-linear load. The stand-alone inverter can be supplies sinusoidal balanced voltage to unbalanced load because the voltage unbalanced factor(VUF) of $V_{LL}$ is reduced from 5.2% to 1.4% in the unbalanced load. Feasibility of control method for a stand-alone inverter will be verified through 30kW stand-alone inverter system.