• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.184-187
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• 1986

A time-division-mutiplexed switching system is implemented for connecting various computers and terminals in the laboratory environment.

• 전력전자학회논문지
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• 제12권6호
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• pp.465-471
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• 2007

본 논문에서는 새로운 소프트 스위칭형 PFC 벅-부스트 AC-DC 컨버터에 대해 연구된다. 제안된 컨버터에 사용된 제어스위치의 턴-온과 턴-오프는 부분공진 동작에 의해 소프트 스위칭으로 되어 스위칭 손실을 줄이고, 입력전류는 듀티율 일정제어에 의한 교류 입력전압의 크기에 비례된 불연속적 유사 펄스열의 정현파 형태를 가진다. 그 결과 컨버터는 효율이 증대되고 입력역률이 증대되는 효과를 가진다. 또한 제안된 컨버터의 출력전압은 제어스위치의 PWM 제어에 의해 조정되고 벅-부스트용 인덕터에 흐르는 전류는 불연속모드로 제어되어 제어회로와 제어기법이 간단한 장점이 주어진다. 제안된 PFC 벅-부스트 컨버터는 기존의 PFC 벅-부스트 컨버터와 비교되어 해석되고 컴퓨터 시뮬레이션과 실험을 통해 그 해석적 타당성이 입증된다.

• 전기학회논문지P
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• 제51권1호
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• pp.10-17
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• 2002

Due to the development of information communication field, the interest of the SMPS(Switched Mode Power Supply) is increased. The size and weight of SMPS are decided by inductor, capacitor and transformer. Thus, the low loss converter which is operated in high speed switching is required. The resonant FB DC-DC converter is able to operate in high speed switching and apply to high power field because the switching loss is low. In this thesis, it is proposed to control strategy for constant output power of resonant FB DC-DC converter in variable input voltage. The proposed control system is a digital I-PD type control and apply to phase-shift resonant type controller. The output voltage tracks reference without steady state error in variable input voltage. The validity of proposed control strategy is verified from results of simulation and experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.158-159
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• 2010

Two-Stage Direct Power Converter(TSDPC) has many merits that possible bidirectional power flow, input power factor own control and system using imaginary DC-link. But TSDPC has some demerits that need many switching devices and switching loss. This paper suggest optimal TSDPC control scheme for improvement for switching loss part by changing the space vector approval times. This paper is verified that 9% improvement in switching efficiency and proposed system has lower harmonic of input currents and output voltage.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권5호
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• pp.231-237
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• 2005

Many conventional multi-level inverters have detected switching faults by using the over voltage and current. However, fault detection of the switching elements is very difficult because the voltage and current due to each switching fault decrease more than the normal operation. Moreover, the dc-link unbalancing voltage causes a serious problem in the safety and reliability of system when the 3-level inverter faults occur Therefore, this paper proposes the simple fault diagnose method and the neutral-point-voltage control method that can protect the 3-level inverter system from the unbalancing voltage of the do-link capacitors when the faults of switching elements occur in the 3-level inverter that is very efficient in ac motor drives of the high voltage and high power applications. Through experiment results, the validity of the proposed method is demonstrated.

• Journal of Power Electronics
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• 제12권5호
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• pp.769-777
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• 2012

In this paper, a new development in the time optimal control theory in sliding mode control systems for multi-quadrant buck converters with a variable load is presented. In general, the closed-loop time optimal control system is applied to multi-quadrant buck converters for output regulation, so that an optimal switching surface is obtained. Moreover, an adjusted optimal sliding mode controller is suggested which adjusts the controller parameters to give an optimal switching surface. In addition, a description of the transient response of the closed-loop system is proposed and used to damp any output or input disturbances in minimum time. Numerical simulations and experimental results are employed to demonstrate that the output regulation time and transient performances of dc/dc converters using the proposed technique are improved effectively when compared to the classical sliding mode control method.

• 전자공학회논문지T
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• 제35T권2호
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• pp.39-47
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• 1998

가변구조 제어기는 이론적으로 빠른 응답특성을 가지며 오버슈트가 없고 외란이나 파라미터 변동에 강인한 제어기로 알려져왔다. 그러나 가변구조 제어기는 모델링과정에서 무시된 플랜트의 고주파 동특성을 여기할 수 있고, 또 시스템을 구성하는 소자들에 손상을 줄 수 있는 채터링현상이 발생하기 때문에 산업현장에서 널리 적용되지 못하고 있다. 본 논문에서는 채터링을 저감시키기 위한 개선된 가변구조 제어기를 제안하고 유도전동기의 위치제어에 적용한다. 기존의 가변구조 제어기는 한 개의 스위칭면을 중심으로 고주파 스위칭을 행하여 시스템의 구조를 절환한 반면에, 개선된 가변구조 제어기는 한 개의 면 대신 슬라이딩 영역을 이루기 위해 두 개의 스위칭면을 가지며 이 영역 내에서 저주파 스위칭으로써 시스템 구조를 절환하게 된다. 그러므로 제안된 알고리즘은 기존의 가변구조 제어기가 가지는 빠른 응답성이나 강인성을 유지하면서 고주파 채터링을 저감시키는 특징을 가지며 전동기정수 변동에도 양호하게 동작하고 있다. 제안하는 제어기의 타탕성을 확인하기 위해 실험을 행하였다.

• Journal of information and communication convergence engineering
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• 제6권4호
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• pp.417-420
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• 2008

Solar electric systems have very little impact on environment, making them one of the cleanest power-generating technologies available. While they are operating, PV systems produce no air pollution, hazardous waste, or noise, and they require no transportable fuels. In PV system design, the selection and proper installation of appropriately-sized components directly affect system reliability, lifetime, and initial cost. In this research, we have studied the PWM(Pulse Width Modulation) signals. I proposed an efficient photovoltaic power interface circuit incorporated with a DC-DC converter and a sine-pwm control method full-bridge inverter. In grid-connected solar power systems, the DC-DC converter operates at high switching frequency to make the output current a sine wave, whereas the full-bridge inverter operates at low switching frequency which is determined by the ac frequency. Thus, it can reduce the switching losses incurred by the full-bridge inverter. Full-bridge converter is controlled by using microprocessor control method, and its operation is verified through computer aided simulations.

• 한국지능시스템학회논문지
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• 제10권3호
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• pp.260-269
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• 2000

The fuzzy and state-feedback control systems have been applied in various areas from non-linear to linear systems. A Fuzzy controller is endowed with control rules and membership function that are constructed on the knowledge of expert, as like intuition and experience. but It is very difficult to obtain the exact values which are the membership function and consequent parameters. though apply back-propagation algorithm to the system, the convergence time a much. Besides, the state-feedback system is most widely used in industry due to its simple control structure and easily able to design the controller. but it is weak in complex system of higher degree and non-linear. In this paper presents the design of a fuzzy switching mode, it these two controllers work at different operation conditions, the advantages of both controller can be retained and the disadvantages can be removed. Between the Fuzzy and the State-feedback controlles, the good outputs are selected by the switching mode. Moreover it is powerful in complex system of higher degree and non-linear. In these sense compared with the state-feedback controller, the performance of the proposed controller was improvedin the section of linearization.

• 제어로봇시스템학회논문지
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• 제14권7호
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• pp.711-719
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• 2008

Although non-real time simulation and pilot based evaluations are available for the development of flight control computer prior to real flight tests, there are still many risky factors. The control law designed for prototype aircraft often leads to degraded performance from the initial design objectives, therefore, the proper evaluation methods should be applied such that flight control law designed can be verified in real flight environment. The one proposed in this paper is IFS(In-Flight Simulator). Currently, this system has been implemented into the F-18 HARV(High Angle of Attack Research Vehicle), SU-27 and F-16 VISTA(Variable stability. In flight Simulation Test Aircraft) programs. This paper addresses the concept of switching mechanism for FLCC(Flight Control Computer)-SWMC(Switching Mechanism Computer) using 1553B communication based on flight control law of advanced supersonic trainer. And, the fader logic of TFS(Transient Free Switch) and stand-by mode of reset '0' type are designed to reduce abrupt transient and minimize the integrator effect in pitch axis control law. It hans been turned out from the pilot evaluation in real time that the aircraft is controllable during the inter-conversion process through the flight control computer, and level 1 handling qualities are guaranteed. In addition, flight safety is maintained with an acceptable transient response during aggressive maneuver performed in severe flight conditions.