• Journal of Institute of Control, Robotics and Systems
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• v.2 no.3
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• pp.165-173
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• 1996

It is not desirable to have too large control input in control systems, because there are usually a limitation for the input magnitude and cost for the input energy. Previous papers in the iterative learning control did not considered on these points. In this paper, an iterative learning control method is proposed for a class of nonlinear systems with consideration on input magnitude by adopting a concept of cost function consisting of the output error and the input magnitude in quadratic form. We proposed a new input update law with an input penalty function. If we choose a reasonable input penalty function, the two control objectives, good command following and small input energy, can be achieved. The characteristics of the proposed method are shown in the simulation examples.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.155-158
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• 1997

In this paper, we present new results concerning the relationship between the input-output and Lyapunov stability of nonlinear system possessing a periodic orbit. Definition of small-signal finite-gain L$\sub$p/ stability around periodic orbit is introduced. We show L$\sub$p/ stability of exponentially stable periodic orbit using quadratic Lyapunov functions for the periodic orbit. The L$\sub$2/ gain analysis is presented with Hamiltonian-Jacobi inequality along with an example.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.455-459
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• 1998

In this paper input Series-Output Parallel connected converter configuration for high voltage power conversion applications is proposed and a control method to solve the problems of Input Series-Output Paralles connected converter configuration is introduced. In this configuration snubber circuit or voltage balancing controller that is necessary for the series connection of switching devices is not needed. The effectiveness of this proposed configuration is verified by simulation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.05a
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• pp.43-46
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• 2001

We, in this paper, design the Sugeno-models fuzzy controller by using the membership function modification algorithm and ANFIS, which are clustering and learning the input-output data. The membership function modification algorithm constructs the more concrete fuzzy controller by clustering the input-output data from the fuzzy inference system. ANFIS construct the Sugeno-models fuzzy controller by learning the input-output data from the above controller. We showed that the fuzzy controller designed by our method could have the stable learning and the enhanced performance.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1352-1364
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• 2013

This paper describes a novel structure for single phase Unified Power Quality Conditioner-Distributed Generation (UPQC-DG) with direct grid connected DC-AC converter for low DC output DG systems which can be used not only for compensation of power quality problems but also for supplying of load power partly. This converter has been composed of one full-bridge inverter, one three winding high frequency transformer with galvanic isolation and two cycloconverters. Proper control based on Input Output feedback Linearization is used to tracking the reference signals. The simulation and experimental results are presented to confirm the validity of the proposed approach.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.9
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• pp.851-856
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• 2011

In this paper, the fuzzy output-feedback controller is addressed for a discrete-time nonlinear interconnected systems with common input. The nonlinear interconnected system is represented by a T-S (Takagi-Sugeno) fuzzy model. Based on T-S fuzzy interconnected system, the fuzzy output-feedback controller is designed with common input. The stability condition of the closed-loop system is represented to the LMI (Linear Matrix Inequality) form. PEMFC model is given to show the verification of the controller discussed throughout the paper.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.142-151
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• 2020

This paper presents a DC/DC LLC resonant converter with wide input/output voltage gain characteristics and its control method for efficiency improvement. For a wide input/output voltage gain characteristics without designing small transformer magnetization inductance, the proposed converter changes the topology into three modes of operation according to the main switch switching pattern. In each operating mode, variable LINK voltage modulation and frequency modulation were performed to control output voltage and improve operating efficiency. A prototype of a 5-kW DC/DC LLC resonant converter was built and tested to verify the validity and applicability of the proposed converter.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.399-411
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• 2003

A model predictive control method is applied to design an automatic controller for thermal power control in a reactor core. The basic concept of the model predictive control is to solve an optimization problem for a finite future at current time and to implement as the current control input only the first optimal control input among the solutions of the finite time steps. At the next time step, the second optimal control input is not implemented and the procedure to solve the optimization problem is then repeated. The objectives of the proposed model predictive controller are to minimize the difference between the output and the desired output and the variation of the control rod position. The nonlinear PWR plant model (a nonlinear point kinetics equation with six delayed neutron groups and the lumped thermal-hydraulic balance equations) is used to verify the proposed controller of reactor power. And a controller design model used for designing the model predictive controller is obtained by applying a parameter estimation algorithm at an initial stage. From results of numerical simulation to check the controllability of the proposed controller at the $5\%/min$ ramp increase or decrease of a desired load and its $10\%$ step increase or decrease which are design requirements, the performances of this controller are proved to be excellent.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.40-46
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• 2018

In this study, the output voltage balancing characteristics of parallel-input series-output (PISO) boost converter is analyzed. The PISO boost converter is derived by combining two basic boost converters. In comparison with the conventional three-level boost converter, the PISO boost converter can balance the output voltages under an unbalanced load condition without requiring additional circuit components and control strategy. A 2 kW prototype converter is built and tested to verify the output voltage balancing characteristics of the PISO boost converter.

• Journal of Power Electronics
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• v.19 no.1
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• pp.89-98
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• 2019

This paper analyzes the input side performance of a conventional three-phase to single-phase matrix converter (3-1MC). It also presents the input-side waveform quality under this topology. The suppression of low-frequency input current harmonics is studied using the 3-1MC plus capacitance compensation unit. The constraint between the modulation function of the output and compensation sides is analyzed, and the relations among the voltage utilization ratio and the output compensation capacitance, filter capacitors and other system parameters are deduced. For a 3-1MC without large-capacity energy storage, the system performance is susceptible to input voltage imbalance. This paper decouples the inner current of the 3-1MC using a Lyapunov function in the input positive and negative sequence bi-coordinate axes. Meanwhile, the outer loop adopts a voltage-weighted synthesis of the output and compensation sides as a cascade of control objects. Experiments show that this strategy suppresses the low-frequency input current harmonics caused by input voltage imbalance, and ensures that the system maintains good static and dynamic performances under input-unbalanced conditions. At the same time, the parameter selection and debugging methods are simple.