• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.125-128
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• 2001

In this paper, We proposed the nonlinear controller and observer design for a ball and beam system. Unfortunately, for the ball and beam system, the control coefficient is zero whenever the angular velocity or ball position are zero. Therefore, the relative degree of the ball and beam system is not well defined. The presented the nonlinear controller and observer design is based on the approximation input-output feedback linearization. And we verified that the proposed nonlinear controller and observer scheme is the feasible through a computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.87.5-87
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• 2001

In the past, we presented the tracking system with one sampling delay. In this paper, first we propose a tracking system with N-th sampling delay, in the case where an input-output pulse transfer function of a plant Z$\_$-N/. Secondly we propose a system configuration converting an input-output pulse transfer function of a plant into Z$\_$-N/ with the inverse system of the plant. Moreover, the proposed tracking system configuration is applied to an actual Ball and Beam system and good results are obtained.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2291-2294
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• 2003

In this paper, analysis and control design of ac-dc converter, normally nonlinear time-varying system, using sliding mode controller to achieve fast output voltage response, disturbance rejection and robust system in the presence of load variation are demonstrated. The objective of this method is to develop methodology for output voltage to be constant and input current sinusoidal that results in nearly unity power factor, respectively. In addition the converter can be also bidirectional power flow. Simulation results using Matlab/Simulink show the effectiveness of sliding mode control system compared with linear feedback controller to guarantee enhanced PF>0.98, THD<5%, and ripple output voltage is less than 1% at the maximum output power.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.197-202
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• 1991

Recently, an output feedback variable structure control scheme(OFVSCS) is proposed to remove the assumption of full state availability and to make the application of VSC scheme to the high order systems with unmeasurable state variables possible. In this paper, a design method of an output feedback variable structure control system (IOFVSCS) that guarantees the invariance of the sliding mode against process parameter variation and external disturbance is proposed. The IOFVSCS is composed of two components; dynamic switching surface driven by measured I/0 informations and switching control input generator driven by switching surface information and measured output, where the two components are constructed by adopting unknown vector modelling approach. The invariance condition for the IOFVSCS is proved to be the same as that of the conventional VSCS. Simulation results show that the IOFVSCS can be designed to have robust properties better than that of the conventional VSCS in spite that the IOFVSCS is driven by small amount of measured information.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.4
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• pp.177-183
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• 2001

In this paper, a new variable structure controller is designed for the tracker control of uncertain general plants so that the output of plants can controlled to a given arbitrary point in state space. By using the error between the steady state value of the output and the given reference, the sliding surface is defined, in advance, the surface from an initial state to the given reference without any reaching phase. A corresponding control input to satisfy the existence condition of the sliding mode is suggested to control the output on the predefined surface. Therefore the output controlled by the proposed controller is completely robust and identical to that of the sliding surface. Through an example, the usefulness is verified.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.8
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• pp.495-497
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• 2005

Recently Neural Network techniques have widely used in adaptive and learning control schemes for production systems. However, generally it costs a lot of time for learning in the case applied in control system. Furthermore, the physical meaning of neural networks constructed as a result is not obvious. And this method has been used as a learning algorithm to estimate the parameter of a neural network used for identification of the process dynamics of s signal input and signal output system and it was shown that this method offered superior capability over the conventional back propagation algorithm. This controller is designed by using three-layered neural networks. The effectiveness of the proposed Neural Network-based control scheme is investigated through an application for a production control system. This control method can enable a plant to operate smoothy and obviously as the plant condition varies with any unexpected accident. This paper goal estimate input signal about controller using neural networks.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.18-20
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• 2005

Recently Neural Network techniques have widely used in adaptive and learning control schemes for production systems. However, generally it costs a lot of time for learning in the case applied in control system. Furthermore, the physical meaning of neural networks constructed as a result is not obvious. And this method has been used as a learning algorithm to estimate the parameter of a neural network used for identification of the process dynamics of s signal input and signal output system and it was shown that this method offered superior capability over the conventional back propagation algorithm. This controller is designed by using three-layered neural networks. The effectiveness of the proposed Neural Network-based control scheme is investigated through an application for a production control system. This control method can enable a plant to operate smoothy and obviously as the plant condition varies with any unexpected accident. This paper goal estimate input signal about controller using neural networks.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.327-331
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• 2008

The problems of power factor and harmonics are occurred in converter system which used to SCRs and diodes as power semiconductor devices IGBT was solved that problem, maintain the input line current with sinusoidal wave current of input power source voltage. In this paper, three phase AC to DC boost converter that operates with unity power factor and sinusoidal input currents is presented. The current control of the converter is based on the space vector PWM strategy with fixed switching frequency and the input current tracks the reference current within one sampling time interval. Space vector PWM strategy for current control was materialized as a digital control method. By using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the dc link.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.358-369
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• 2000

Shielded metal arc welding machines with AC transformer have been widely used for thin-plate welding applications. Because of being bulky, heavy and of tap-changing property, so the SMAW's are changing to new power electronic circuits such as inverter circuit in order to reduce the system size and also to improve the welding performances at input output sides. The PWM inverter arc welding machine with diode rectifier has better output welding performances but it is has the plentiful harmonics and the lower input power factor. To solve these problems, input current-controlled scheme is considered for PWM inverter arc welding system, and then total input power factor is maintained to be more than 99%. Also a new combined control is proposed which can control both instantaeous welding output voltage and current under constant power condition, and as a result the variations of instantaneous current and voltage can be reduced to very narrow range in the V-I curve relationship, and hence the variance of welding current and voltage become so reduced. In addition the spatter generated during welding process is greatly reduced up to 70%. And the overall effiency can be improved up to 10%, which becomes higher when the load is lower.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1987-1992
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• 2004

A Variable Structure Model Reference Adaptive Controller (VS-MRAC) using state Variables is proposed for single input multi output systems. . The structure of the switching functions is designed based on stability requirements, and global exponential stability is proved. Transient behavior is analyzed using sliding mode control and shows perfect model following at a finite time. The effect of input disturbances on stability and transients is investigated and shows preference to the conventional MRAC schemes with integral adaptation law. Sliding surfaces are independent of system parameters and therefore VS-MRAC is insensitive to system parameter variations. Simulation is presented to clear the theoretical results.