• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.299-305
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• 2013

The complexity and severe nonlinearity of multi-machine power systems make it difficult to design a control input for voltage regulation using modern control theory. This paper presents a model-based PID control scheme for the regulation of the bus voltage to a desired value. To this end, a fourth-order linear system is constructed using input and output data obtained using the TSAT (Transient Security Assessment Tool); the input is assumed to be applied to the grid through the STATCOM (STATic synchronous COMpensator) and the output from the grid is a bus voltage. On the basis of the model, it is identified as to which open-loop poles of the system make the response to a step input oscillatory. To reduce this oscillatory response effectively, a model-based PID control is designed in such a way that the oscillatory poles are no longer problematic in the closed loop. Simulation results show that the proposed PID control dampens the response effectively.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.522-524
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• 2018

A New Direct AC LED Driver has been proposed for wide output power range and precise constant current regulation using an advanced auto commutation topology. The conventional shunt regulation method provides a stepped input current shape by fixed regulation references in the linear regulator of the each channel, which results in poor current regulation and high THD. The conventional method needs to assign a linear regulator in each LED channel so that the number of linear regulator increases when extending the number of channels especially at high power application. The proposed regulation method can drive multiple switches to regulate each LED channel current by a single amplifier with sinusoidal reference so that large number of LED channel can be simply extended with less BOM cost and low THD is obtained with the accurate current regulation thanks to the sinusoidal input current control in the closed loop control. To confirm the validity of the proposed circuit, theoretical analysis and experimental results from a 20-W LED driver prototype are presented.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.6
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• pp.451-457
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• 1989

The current-fed DC-DC converter, which is known as the most stable DC-DC converter, has a two-winding reactor in series with the input. In this paper a new double-output DC-DC converter circuit, in which the 2nd winding of the reactor is creating the 2nd output, while the 2nd winding is feeding the energy to the input in the current-fed converter, is propose. The steady state characteristics of the new circuit are clarified and it is found that the maximum value exists in the 2nd output. Furthermore, regulation characteristic is analysed by 'Slope method' and the result shows good agreement with experimental value. The 2nd output voltage regulation is performed by using regulation IC. As a result, we have achieved good regulation characteristics.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.183-185
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• 2006

This paper presents a SISO nonlinear controller for the power system consisting of a synchronous generator connected to an infinite bus. The proposed controller is based on input-output feedback linearization, with a modified version of the terminal voltage equation used as the output. The resulting closed-loop has no internal dynamics, and thus stability is guaranteed. The controller performance is seen to be effective through simulations.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2125-2133
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• 2018

To achieve high performance speed regulation, a robust adaptive speed controller is proposed for the permanent magnet synchronous motor (PMSM) subject to parameter uncertainties and input saturations in this paper. A nonlinear adaptive control is introduced to compensate the PMSM speed tracking errors due to uncertainties, disturbances and control input saturation constraints. By combining the adaptive control and the nonlinear robust control based on the interconnection and damping assignment (IDA) strategy, a new robust adaptive control is designed for speed regulation of PMSM. Stability and robustness of the closed-loop control system involved with the constrained control inputs rather than unconstrained control inputs are validated. Simulations for PMSM control in the presence of uncertainties and saturations nonlinearities show that the proposed approach is effective to regulate speed, and the average tracking error using the proposed approach is at least 32% smaller than the compared methods.

• Journal of Power Electronics
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• v.15 no.4
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• pp.886-898
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• 2015

The design feasibility of a micro unidirectional DC transmission system based on an input-parallel output-parallel (IPOP) converter is analyzed in this paper. The system consists of two subsystems: an input-parallel output-series (IPOS) subsystem to step up the DC link voltage, and an input-series output-parallel (ISOP) subsystem to step down the output voltage. The two systems are connected through a transmission line. The challenge of the delay caused by the communication in the control system is addressed by introducing a ring communication structure, and its influence on the control system is analyzed to ensure the feasibility and required performance of the converter system under practical circumstances. Simulation and experiment results are presented to verify the effectiveness of the proposed design.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.821-824
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• 1993

This paper deals with a $3{\phi}$ rectifier unit for telecommunication system. The rectifier unit is developed to Cope with the step-up of the AC input voltatage from 220V to 380V. By using a buck-type converter in the front-end, it keeps the input power factor high and reduces the voltage ripple in the dc output. It also has a very wide voltage regulation range, which lets the unit be applied for both the 220V and 380V input system. The study includes the power conversion scheme, control strategy, snubber circuit and finally, experimental results.

• Journal of IKEEE
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• v.24 no.4
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• pp.1162-1166
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• 2020

In this paper Low Drop-Out (LDO) regulator that improved load regulation characteristics due to the feedback detection structure. The proposed feedback sensing circuit is added between the output of the LDO's internal error amplifier and the input of the pass transistor to improve the regulation of the delta value coming into the output. It has a voltage value with improved load regulation characteristics than existing LDO regulator. The proposed LDO structure was analyzed in Samsung 0.13um process using Cadence's Virtuoso, Spectre simulator.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1032-1039
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• 2011

This paper presents results of input shaping to industrial cranes. A brief theoretical background for input shaping is described. Several examples of input shaping application to sway regulation for industrial cranes are presented. The presented results show that input shaping is very useful for industrial cranes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1759-1771
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• 2017

In this paper, an improved continuous integral variable structure systems(ICIVSS) with the prescribed control performance is designed for simple regulation controls of uncertain general linear systems. An integral sliding surface with an integral state having a special initial condition is adopted for removing the reaching phase and predetermining the ideal sliding trajectory from a given initial state to the origin in the state space. The ideal sliding dynamics of the integral sliding surface is analytically obtained and the solution of the ideal sliding dynamics can predetermine the ideal sliding trajectory(integral sliding surface) from the given initial state to the origin. Provided that the value of the integral sliding surface is bounded by certain value by means of the continuous input, the norm of the state error to the ideal sliding trajectory is analyzed and obtained in Theorem 1. A corresponding discontinuous control input with the exponential stability is proposed to generate the perfect sliding mode on the every point of the pre-selected sliding surface. For practical applications, the discontinuity of the VSS control input is approximated to be continuous based on the proposed modified fixed boundary layer method. The bounded stability by the continuous input is investigated in Theorem 3. With combining the results of Theorem 1 and Theorem 3, as the prescribed control performance, the pre specification on the error to the ideal sliding trajectory is possible by means of the boundary layer continuous input with the integral sliding surface. The suggested algorithm with the continuous input can provide the effective method to increase the control accuracy within the boundary layer by means of the increase of the $G_1$ gain. Through an illustrative design example and simulation study, the usefulness of the main results is verified.