• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1331-1333
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• 1999

In Haenam-Cheju HVDC link several modes of operations and controls are provided, which are constant frequency control, constant power control and constant current control. This paper describes basic control action of converters under three control modes and shows EMTDC simulation results at ground fault and steady state respectively.

• 조명전기설비학회논문지
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• 제22권8호
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• pp.45-51
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• 2008

본 논문에서는 2.5[kW]급 선박용 HID 탐사등 조명을 위한 Soft-start 개방회로 전압 및 정전류 순차 제어 방식을 제안한다. 제안된 제어회로는 HID 탐사등의 안정적인 점등을 위하여 개방회로 전압과 점등 전류를 순차적으로 제어하는 방식으로, 특히 전원투입 상태에서의 안정성을 위하여 일정한 입력전압에 대해서 Soft-start 기법을 적용하여 개방회로 전압 제어모드로 동작하도록 설계되었다. 또한, 점등개시 신호의 입력에 따라 제어모드를 전압제어에서 전류 제어모드로 변경하여 단일 PWM 제어소자에서 동시에 처리하도록 하였다. 한편, 입력 노이즈 및 개방회로 전압의 검출을 간단한 원칩 마이크로 프로세서로 구현하여, 오동작 및 점등 실패에 대한 강인성을 부가하도록 하였다. 제안된 제어기는 실제 선박용 HID 탐사등의 적용 시험을 통하여 그 안정성을 시험하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권11호
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• pp.611-616
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• 1999

The introduction of the eddy current braking(ECB) system in HSRT(high speed railway train) is known to be advantageous, in that the system is independent on wheel-rail adhesion coefficient which is greatly affected by weather condition. It also minimize the maintenance of the brake system and does not require any additional electric energy because it is powered form the regenerated power at the time of the braking. In this study, the braking and attraction forces of the ECB are simulated by 2-D FEM and are experimentally verified on a down-scaled prototype. A control algorithm of the ECB is proposed to generate constant braking torque using linear variation of the reference current according to speed. Experimental results shows that the constant torque is generated over all operating speed region by developed control algorithm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.110-113
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• 2000

In general, speed control method of the elevator system has used motor pole change type or motor primary voltage control type. But it will change to vector control type in order to increase it's reliability, riding comfort and decrease material cost. It is the conception of vector control type in order to increase it's reliability, riding comfort and decrease material cost. It is the conception of vector control that primary current of the induction motor be controlled independently with magnetizing current(field current of DC motor) and torque current(armature current of DC motor). In this paper, by analyzing the effect of the time constant variation of rotor of the induction motor on the slip frequency type indirect vector control, a drive system for the motor will be constructed using a fuzzy slip frequency type indirect vector controller with fuzzy control method for estimating the vector time constant in the slip frequency type indirect vector control. The goal of this study is to enabling even more efficient speed control by constructing on elevator driver based on the newly developed drive system.

• Journal of Power Electronics
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• 제16권3호
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• pp.840-848
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• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.376-379
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• 1998

This paper be described the constant speed control of induction motor for high performance. Vector control system which is used the stator current, voltage of IM is modeled without the speed, flux sensor. The proposed control system be simulated using Matlab with Simulink. Results include the fast response of the constant speed and torque in proposed system. For high performance, this paper presents the robust characteristics of field oriented control system for IM.

• 전력전자학회논문지
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• 제20권2호
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• pp.182-192
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• 2015

This study develops a digital control scheme with power factor correction for a front-end converter in an electric vehicle battery charger. The front-end converter acts as the boost-type switching-mode rectifier. The converter assumes the two roles of the battery charger, which include power factor control and robust charging performance. The proposed control scheme consists of a charging control algorithm and a grid current control algorithm. The scheme aims to obtain unity input power factor and robust performance. Based on the linear average model of the converter, a constant-current constant-voltage charging control algorithm that passes through only one proportional-integral controller and a current feed-forward path is proposed. In the current control algorithm, we utilized a second band pass filter, a single-phase phase-locked loop technique, and a duty-ratio feed-forward term to control the grid current to be in phase with the grid voltage and achieve pure sinusoidal waveform. Simulations and experiments were conducted to verify the effectiveness of the proposed control scheme, both simulations and experiments.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.443-451
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• 2015

The stability of a multi-terminal direct current (MTDC) system is often influenced by its control strategy. To improve the stability of the MTDC system, the control strategy of the MTDC system must be appropriately adopted. This paper deals with estimating stability of a MTDC system based on the line-commutated converter based high voltage direct current (LCC HVDC) system with an inverter with constant extinction angle (CEA) control or a rectifier with constant ignition angle (CIA) control. In order to evaluate effects of two control strategies on stability, a MTDC system is tested on two conditions: initialization and changing DC power transfer. In order to compare the stability effects of the MTDC system according to each control strategy, a mathematical MTDC model is analyzed in frequency domain and time domain. In addition, Bode stability criterion and transient response are carried out to estimate its stability.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.21-24
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• 2002

The vector control system of an induction motor is the high performance drive system to achieve the instantaneous torque control. The vector control system is greatly divided into the direct control, and the indirect control that the most widely is used, The indirect vector control needs the rotor time constant, which changes widely according to the temperature, frequency, and current amplitude. The incorrect time constant leads to the saturation of magnetic flux or under-excitation phenomena. As a result, that deteriorate the control performance. Therefore, in this paper, the effect of time constant variation is investigated and its on-line tuning algorithm is proposed. The time constant using the torque angles was calculated and that of the validity of algorithm proposed was proved through the computer simulation and the experiment.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.97-105
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• 2013

The control method of the bidirectional DC/DC converter for instantaneous regenerative current control is described in this paper. The general method to control the DC/DC converter is the output voltage control. However, the regenerative current cannot be controlled to be constant with this control method. To improve the performance of the conventional control method, the DC-link voltage of the inverter is controlled within the tolerance range by the instantaneous boost and buck operations of the bidirectional DC/DC converter. By the proposed control method, the battery current can be controlled to be constant regardless of the motor speed variation. The improved performance of the DC/DC converter controlled by the proposed control method is verified by the experiment and simulation of the system with the inverter and IPMSM(Interior Permanent Magnet Synchronous Motor) which is operated by the reduced practical speed profile.