• 대한전기학회논문지
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• 제34권12호
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• pp.472-484
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• 1985

A design of robust voltage controller for high speed excitation of synchronous machine was carried out by pole assignment techniques. An affine map from characteristic polynomial coefficients to feedback parameters is formulated in order to place the system eigen values in the desired region. The feedback parameters determined from linearized model are tested on nonlinear model subjecting it to small disturbances and system faults to show the effectiveness of the controller designed by the proposed technique. The results obtained indicate that the controller presented improves the dynamic stability and system performances of conventionally controlled synchronous machine significantly.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.202-202
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• 2000

In this paper, the synchronous generator model which is derived from the swing equation and the Park's equation is transformed to an adequate form for feedback linearization. And the single controller is designed in order to play the role of both PSS and AVR. The result of the simulations shows that the stability of the system is guaranteed in the wide range of operating points.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.669-671
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• 2004

This paper presents a MIMO nonlinear controller for the power system consisting of a turbine and a synchronous generator connected to an infinite bus. The controller proposed is based on feedback input-output linearization; its main goal is to regulate the terminal voltage and frequency, and is to improve the transient stability under large disturbances and unexpected faults. It is guaranteed that the voltage converges to its reference value exponentially, and that the frequency and the mechanical/electrical power are bounded. The design procedure is tested on a single machine infinite bus power system through simulations, and is seen to be effective.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.385-387
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• 1996

A novel two stage soft-switching ac-to-dc convener with power factor correction is proposed. The proposed convener provides zero-voltage-switching (ZVS) condition to main switch of boost pre-regulator without auxiliary switch. Comparing to the conventional two stage approach(ZVS-PWM boost rectifier followed by off-line ZVS dc-dc step down converter), the proposed approach is simple and reducing EMI noise problem. A new simple DC-linked energy feedback circuit provides zero-voltage-switching condition to boost pre-regulator without imposing additional voltage and current stresses and loss of PWM capability. Operational principle, analysis, control of the proposed converter together with the simulation results of 1KW prototype are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.234-238
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• 1998

Parameter estimation of induction motor for vector control presented in this paper can be easily implemented and applied to inverters in the industrial field, because it needs no additional hardware such as voltage sensor and measuring equipment. At first, the stator resistance including switching loss of inverter is measured by simple voltage-current equation. Next, in pre-magnetization of machine by imposing the d-axis constant field-current, q-axis torque current is forced to the machine until its speed feedback reachs to pre-defined level of speed limit. At this time, we can measure the rotor time-constant by decreasing the distorted output-voltage of inverter. At last, stator inductance, transient inductance, and moment of inertia can be measured by the relationship of output voltage, output torque and speed feedback. The validity and usufulness of this method is verified by experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.266-267
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• 2017

To synchronize the distributed generation (DG) unit with the grid, the voltage sensors are generally employed to obtain the grid phase angle. This paper presents an observer-based voltage sensorless control scheme for a three-phase inverter connected to the grid through an LCL filter. The proposed control scheme consists of an augmented state observer and a feedback controller. The augmented state observer is used to estimate the grid voltages and states of the inverter system, which are then employed to determine the grid voltage angle and to construct the feedback controller. As a result of using the observer, only the grid current sensors are required to accomplish the control scheme. The simulation results are given to prove the validity of the proposed control scheme.

• 한국정보전자통신기술학회논문지
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• 제16권4호
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• pp.167-172
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• 2023

본 논문에서는 3개의 부궤환 루프를 가진 저잡음 위상고정루프를 제안하였다. 기존 구조의 위상고정루프는 하나의 부궤환 루프로 구성되어 있어 잡음 특성 개선이 쉽지 않다. 추가된 부궤환 루프는 지터 특성을 결정하는 전압제어발진기의 입력 전압 크기를 줄여주는 역할을 하여 기존 구조로 쉽지 않은 잡음 특성 개선을 가능하게 해준다. 시뮬레이션 결과는 부궤환 루프가 추가될 때마다 지터 특성이 개선되는 것을 보여주고 있다. 전력의 경우 10% 정도 약간 상승하게 되지만, 지터 특성은 2배 정도 개선된다. 제안된 위상고정루프는 1.8V 180nm CMOS 공정을 이용하여 Hspice로 시뮬레이션 하였다.

• Journal of Power Electronics
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• 제15권6호
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• pp.1456-1467
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• 2015

This paper presents a novel close-loop control scheme based on small signal modeling and weighted composite voltage feedback for a three-phase input and single-phase output Matrix Converter (3-1MC). A small non-polar capacitor is employed as the decoupling unit. The composite voltage weighted by the load voltage and the decoupling unit voltage is used as the feedback value for the voltage controller. Together with the current loop, the dual-loop control is implemented in the 3-1MC. In this paper, the weighted composite voltage expression is derived based on the sinusoidal pulse-width modulation (SPWM) strategy. The switch functions of the 3-1MC are deduced, and the average signal model and small signal model are built. Furthermore, the stability and dynamic performance of the 3-1MC are studied, and simulation and experiment studies are executed. The results show that the control method is effective and feasible. They also show that the design is reasonable and that the operating performance of the 3-1MC is good.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1612-1614
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• 1994

Modulators Installed in PLS(Pohang Light Source) Linac are composed of a DC high voltage section, a charging section and a discharging section. PFN is charged by a resonant charging mechanism, and discharged by a switching device through the primary of the pulse transformer connected to a load. Charged PFN voltage must be well regulated to obtain stable output pulse voltage at the load. For this purpose, DCHV is controlled by a SCR controller with feedback signal, and PFN voltage is regulated by a De-Q'ing circuit. The full power operation test shows the pulse voltage regulation within ${\pm}0.13%$ with SCR feedback control alone, and within ${\pm}0.08%$ together with De-Q'ing. This paper describes the design concept and operational characteristics of the De-Q'ing circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.312-317
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• 1996

This paper compares the output voltage control strategies of three-phase PWM inverter for uninterruptible power supply. The feedforward control, feedforward/feedback control, and decoupled feedback control in both the synchronous reference frame and the stationary reference frame are examined. In particular, it is shown that the response of the decoupled feedback controller in the synchronous reference frame can be improved by pole-zero cancellation method. It is also shown that the pole-zero cancellation method reduces to the deadbeat control, when it is implemented with digital controller.