• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.666-672
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• 2003

This paper presents a design of the controller for vehicle lateral dynamics using active yaw moment. Vehicle lateral motion is incorporated with directional controllability and stability. These are conflicting each other from the view of vehicle handling performance. To compromise the trade-off between these two aspects, we suggest a new control algorithm based on the sliding mode with time-varying switching surface according to the body side slip angle. The controller can deal with the nonlinear region in vehicle driving condition and be robust to the parameter uncertainties in the plant model. Control performance is evaluated from the simulation for the vehicle of real parameters on the road with various tire-road frictions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.193-200
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• 2010

In this paper, the eigenvalue sensitivity analysis is calculated in the power system which is including both generator controllers such as Exciter, PSS and thyristor controlled FACTS devices in transmission lines such as TCSC. Exciter and PSS are continuously operating controllers but TCSC has a switching device which operates non-continuously. To analyze both continuous and non-continuous operating equipments, the RCF method one of the numerical analysis method in discrete time domain is applied using discrete models of the power system. Also the eigenvalue sensitivity calculation algorithm using state transition equations in discrete time domain is devised and applied to a sampled system. As a result of simulation, the eigenvalue sensitivity coefficients calculated using discrete system models in discrete time domain are changed periodically and showed different values compared to those of continuous system model in time domain by the effect of periodic switching operations of TCSC.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.233-235
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• 2000

SVC(Static Var Compensator) is commonly installed with conventional mechanically switched existing reactor or capacitor banks for wide range voltage control. The frequencies of switching of external banks have a great impact on the quality of voltage, but is limited since the life time of the external banks depends severely on the number of switching. So it is a complete multi-objective nonlinear optimization problem with conflicting objectives. This paper presents a method to determine the optimal coordination of SVC and external banks using genetic algorithm based on the multi-objective criteria. Optimal dead band and delay time of external banks is sought for reliable and efficient operation

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.211-218
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• 1998

As a part of trajectory modulation to increase system survivability and terminal effectiveness, impact angle control is required in the terminal phase of tactical missile systems. The missile systems are not allowed to have high altitude to reduce probability of detection by sensors of missile defense systems. In this paper, an analytic form of a time-optimal control law is suggested in the case of constrained missile maneuverability and impact angle under the assumption of a zero-lag autopilot. The control law is obtained by establishing optimal missile-target engagement geometry in the vertical plane. Extension of the law for missiles with autopilot response lags requiring a numerical solution is studied by introducing an iterative algorithm for optimal switching time determination of which the initial switching instants are obtained from the analytic solution. Also suggested is a closed-form impact angle control law derived by an energy-optimal approach. The performances of the proposed guidance laws are evaluated by a series of computer runs.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.12B no.1
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• pp.31-36
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• 2002

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position; therefore, the position of rotor is an essential information. Although optical encoders or resolvers are used to provide the position information, these sensors are expensive. Moreover, in the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost analog encoder suitable for practical applications is proposed. And the control algorithm to generate switching signals using a simple digital logic is presented. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.924-926
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• 1999

To reduce chattering in sliding mode control, a boundary layer around the sliding surface is used, and a continuous control is applied within the boundary. In this paper, a method of determining the sliding mode controller switching gains and the width of boundary layer is presented. Contrary to the trial and error selection of the switching gains and the width of boundary layer, the selection in the presented work is done using genetic algorithms. Simulation results show that the system performance has been improved.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.231-235
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• 1988

In this paper we present a new method to control system design using a sliding mode. The objective of this research is to develop the algorithm for the sliding mode control which is able to remove the chattering phenomena and to reduce the reaching phase. To accomplish this approach we introduce switching dynamics instead of switching logics to obtain the sliding mode. Consequently, we can obtain the new design approach which is much simpler than the VSS theory. And there do not exist chattering phenomena in this method because the obtained control input are continuous. Simultaneously we can reduce the reaching phase by a suitable choice of design factor. Numerical examples are discussed as illustration.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1089-1094
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• 2016

In order to establish the robust controller design technique of series wound motor driver system. This paper proposes a method of Bang-Bang controller using a series wound motor driver system under improperly variable load. A Bang-Bang controller structure is simpler than the structure of PID plus Bang-Bang controller. This paper shows that a general 8 bits microprocessor is used efficiently implementing such an algorithm. The calculation time of software is extremely small when compared with conventional PID plus Bang-Bang controller. Both nonlinear operating characteristics of digital switching elements and describing function methods are used for the analysis and synthesis. Real time implementation of Bang-Bang controller is achieved. Concept design strategy of the control and PWM waveform generation algorithms are presented in the paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.77-85
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• 2009

With the advent of power semiconductor switching devices, power electronics relating to high frequency electromagnetic eddy current based induction heating technology have become more suitable and acceptable. This paper presents high-frequency induction heating cooking appliance circuit based on the zero current switching-PWM single ended push-pull(ZCS-PWM SEPP) resonant inverter added AC-DC converter. This inverter uses pulse-width-modulation(PWM) control method with active auxiliary quasi-resonant lossless inductor snubbers and a switched capacitor. To improved the transient performance, the PI controller is applied for this system. For the systematic parameter optimization of the PI controller, the gradient-based optimization algorithm is applied. The performance of optimized parameters is evaluated using simulation and experimental test. These results show that the proposed systematic optimal tuning method improve the transient performances of this system.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.149-151
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• 2007

For several decades, VSC has gained much attention as one of the useful design tools for handling the practical system with uncertainties or disturbances. Generally, the disturbances in the matching condition can be perfectly rejected via VSC; however, these in the mismatching condition are known to be hardly rejected. There have been some trials on it, in which the resulting controls in fact belong to the class of robust control guaranteeing disturbance ${\gamma}$-attenuation. Therefore, in this paper, we propose a new Variable Structure Control (VSC) for a system with mismatched disturbances. The proposed controller is composed of linear and nonlinear parts; the former plays a role in stabilizing the system and the latter takes care of attenuating the disturbances. The main contribution is to introduce the concept of switching-zone, rather than switching-surface, that is designed through piece-wise Lyapunov functions. The resulting non-convex conditions are formulated with an iterative linear programming algorithm, which provides an excellent performance of almost rejecting the disturbances.