• 한국소음진동공학회논문집
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• 제16권2호
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• pp.207-213
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• 2006

In our previous research, we proposed a robust saturation controller which involves both control input saturation and structured real parameter uncertainties. This controller can analytically prescribed the upper and lower bounds of parameter uncertainties, and guarantee the closed-loop robust stability of the system in the presence of actuator's saturation. And the availability and the effectiveness of the proposed robust saturation controller were verified through numerical simulations. In this paper, we verify the robust stability of this controller through experimental tests. Expecially, we show unstable cases of other controllers in comparison with this controller. Experimental tests are carried out in the laboratory using a two-story test structure with a hydraulic-type active mass damper.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권5호
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• pp.249-256
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• 1999

This paper describes static characteristics analysis of linear pulse motor(LPM) with two permanent magnets. Linear pulse motors are finding a wide range of application for the Factory-Automation or the Office-Automation. Typically, LPM provides for a reliable and precise control of position, velocity, or acceleration without using a closed-loop system. Some of the advantages of LPMs are ease of control, step multiplication, static and dynamic positioning, and locking force. The flux density and thrust of LPM is computed by the FEM and magnetic equivalent circuits which considered the magnetic nonlinear phenomena. The result of characteristics analysis are shown as the flux, the air gap reluctance and the thrust. The velocity and position characteristics as a function of unit step input is measured. To estimate the unit step response charecteristic of LPM, the simulation results by Matlab and the experimental results is compared.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.407-409
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• 1998

In order to improve the tracking performance of $2{\times}2$ multivariable control systems, a fuzzy control algorithm with feedforward compensator is represented. The method consists in two steps. First, neglecting interconnections. one designs a fuzzy controller to each individual loop. In the second stage, low-order transfer functions of outputs to reference inputs are estimated. We propose a design method of the feed forward compensator based on the transfer functions. An illustrative example are shown.

• 제어로봇시스템학회논문지
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• 제14권3호
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• pp.226-231
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• 2008

In this paper, we propose novel eigenstructure assignment method in full-state feedback for linear time-invariant MIMO system such that directions of some left eigenvectors are exactly assigned to the desired directions. It is required to consider the direction of left eigenvector in designing eigenstructure of closed-loop system, because the direction of left eigenvector has influence over excitation by associated input variables in time-domain response. Exact direction of a left eigenvector can be achieved by assigning proper right eigenvector set satisfying the conditions of the presented theorem based on Moore's theorem and the orthogonality of left and right eigenvector. The right eigenvector should reside in the subspace given by the desired eigenvalue, which restrict a number of designable left eigenvector. For the two cases in which desired eigenvalues are all real and contain complex number, design freedom of designable left eigenvector are given.

• Journal of Power Electronics
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• 제9권4호
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• pp.582-592
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• 2009

This paper proposes a new speed sensorless direct torque and flux controlled interior permanent magnet synchronous motor (IPMSM) drive. Closed-loop control of both the torque and stator flux linkage are achieved by using two proportional-integral (PI) controllers. The reference voltage vectors are generated by a SVM unit. The drive uses an adaptive sliding mode observer for joint stator flux and rotor speed estimation. Global asymptotic stability of the observer is achieved via Lyapunov analysis. At low speeds, the observer is combined with the high frequency signal injection technique for stable operation down to standstill. Hence, the sensorless drive is capable of exhibiting high dynamic and steady-state performances over a wide speed range. The operating range of the direct torque and flux controlled (DTFC) drive is extended into the high speed region by incorporating field weakening. Experimental results confirm the effectiveness of the proposed method.

• 대한전기학회논문지
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• 제35권8호
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• pp.309-315
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• 1986

We proposed a preliminary Data Flow Machine Model(DNL1) operating on the basis of Node Label. In this model, all the PMs(Processing Modules) were synchronized with the content of LC(Level Counter) and were not implemented dy the processing cability on conditional nodes. This paper presents an architecture of a concurrent multiprocessor system which was developed from DNL1 with two additional types of memories, CF(Control Flag) and ETF (Enabled Token Flag). The CF memory holds the control condition flag ('1' or '0') to be referenced to when a node is fired and the ETF represents the firability of a certain node. Firable nodes are fetched to the PU(Processing Unit) and processed. This Data Flow system can be extended hierarchically by a network of simple modules. The principle working elements of the machine are a set of PMs, each of which performs the execution of the data flow procedures held in a local memory, NTM(Node Token Memory) within the PM.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.712-717
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• 2001

This paper investigates the control problem of evaporator superheat, i.e., the difference between the temperature of the refrigerant at the entrance region of an evaporator and that at the exit region, for multi-type air-conditioning/refrigeration systems. Mathematical equations describing the characteristics of compressor, condenser, evaporator, and electronic expansion valve are first derived. Then, the transfer functions from the current input of the electronic expansion valve to wall temperatures of evaporator tube at two-phase region and superheated region, respectively, are derived. The stability and performance of the closed loop system with a PI controller are analyzed by Nyquist stability criterion. Simulation results are provided.

• 한국철도학회논문집
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• 제4권1호
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• pp.1-8
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• 2001

In this paper, the dynamics and stability of the automated guideway transit (AGT) vehicles with rubber tires are investigated. Two types of AGT systems are considered: the bogie-type and steering-type systems. The critical speeds for the dynamic instability of lateral and yawing motions are investigated by use of the Routh-Hurwitz's stability criterion. It is shown that the bogie-type AGT vehicles are likely to be stable within the range of practical operating speed, whereas it is not true for the steering-type AGT vehicles. It is also shown that the control performance of steering-type AGT vehicles can be improved by choosing proper steering gains of the closed-loop steering control system.

• 제어로봇시스템학회논문지
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• 제13권6호
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• pp.574-580
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• 2007

This paper deals with LQR controller design method tor system having complex poles. The proposed method is capable of systematically calculating weighting matrices based on the pole's moving-range and the relational equation between closed-loop pole(s) and weighting matrices. The method moves complex poles to complex poles or two distinct real poles. This will provide much-needed functionality to apply LQR controller. The example shows the feasibility of the proposed method.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.270-279
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• 2018

This paper elucidates a hysteresis current controller for enhancing the performance of static synchronous compensator (STATCOM) using cascaded H-bridge multilevel inverter. Due to the rising power demand and growing conventional generation costs a new alternative in renewable energy source is gaining popularity and recognition. A five level single phase cascaded multilevel inverter with two separated dc sources, which is energized by photovoltaic - wind hybrid energy source. The voltages across the each dc source is balanced and standardized by the proposed hysteresis current controller. The performance of STATCOM is analyzed by connecting with grid connected system, under the steady state & dynamic state. To reduce the Total Harmonic Distortion (THD) and to improve the output voltage, closed loop hysteresis current control is achieved using PLL and PI controller. The performance of the proposed system is scrutinized through various simulation results using matlab/simulink and hardware results are also verified with simulation results.