• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.169-171
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• 1992

In an automated power distribution systems, the fault situation is controlled from the control center through remotely-controlled sectionalizing switches. In this paper, the service restoration strategy which can yield the minimal switching actions and constraint checking is proposed and an expert system which generates the appropriate switching actions is described.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.13-16
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• 2000

This paper presents a simple class-D stereo amplifier using 3-phase full bridge circuit configurations which is controlled by a new current control switching method. Although this class-D amplifier has an only one current control loop with the proposed switching method, a good performance can be obtained. In this paper, a strategy for driving stereo signal amplifier with 3-phase full bridge is discussed. With the experimental results, usefulness of the proposed amplifier is confirmed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.357-361
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• 1998

A new current controlled PWM technique for a 3-level inverter has been proposed and described in the paper. The proposed current control has the simple structure without needing to calculate the switching angles of the voltage vectors. The output in the proposed inverter contains less harmonic content than that of a conventional current controlled PWM controller, since the current control can be applied to the 3-level inverter. In addition, the proposed current controlled PWM technique has lower switching frequency than that of a conventional current controlled PWM technique at the same current limit. The control method and the performance for a proposed 3-level inverter has been discussed and investigated by the computer simulation.

• 한국정보통신학회논문지
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• 제10권1호
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• pp.96-103
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• 2006

본 논문은 고주파 단상 부스트 컨버터의 스위칭 손실을 감소시킬 수 있는 새로운 방식을 제안한다. 이것은 기존의 부스트 컨버터에 별도의 스위칭 장치를 첨가한 형태를 가진다. 원래의 고속 스위칭 장치는 변함없이 전력변환을 수행하지만, 새로이 부가된 장치는 저속으로 동작하면서 고속 스위칭 소자에 흐르는 전류의 대부분을 우회시켜 스위칭 손실을 감소시킨다. 제안된 방법의 제어시스템은 매우 간단하다. 제어기는 멀티바이브레이터, 비교기 및 AND 게이트로 구성되고, 스위칭 소자의 오프 지속시간이 멀티바이브레이터에 의해 일정하게 유지되므로 최대 스위칭 주파수는 별도의 클럭 발생기 없이 제한된다. 본 논문에서는 제안된 컨버터의 형상, 설계 등을 언급하고 컴퓨터 시뮬레이션을 사용하여 제안된 방법의 스위칭 손실 감소, 효율향상에 관한 유효성을 입증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1094-1096
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• 2002

A new technique for improving the efficiency of single-phase high-frequency boost converter is proposed. This converter includes an additional low-frequency boost converter which is connected to the main high-frequency switching device in parallel. The additional converter is controlled at lower frequency. Most of the current flows in the low-frequency switch and so, high-frequency switching loss is greatly reduced accordingly. Both switching device are controlled by a simple method; each controller consists of a comparator, a frequency generator and an error amplifier. The converter works cooperatively in high efficiency and acts as if it were a conventional high-frequency boost converter with one switching device, The proposed method is verified by simulation and experiment. This paper describes the converter configuration and design, and discusses the steady-state performance concerning the switching loss reduction and efficiency improvement.

• 한국정밀공학회지
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• 제6권2호
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• pp.30-39
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• 1989

Variable structure control (VSC) systems control the state vectors using sliding regime (SR) constructed switching logic, switching plane and control law. Saturation function switching logic is used to improve the drawback which occurs in traditional sign function switching logic. Switching plane with time-varying parameter is proposed to improve the drawback which occurs in switching plane with constant parameter and it is suggested the control law which has time-varying parameter. The stability of VSC system controlled by proposed time-varying SR is discussed, and the good control behavior was shown through computer simulation using proposed SR.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.577-595
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• 2017

${\bullet}$ Silicon Carbide (SiC) had excellent material properties as the base material for next generation of power semiconductor. In developing SiC MOSFET, gate oxide reliability issues had to be first overcome before commercial application. Besides, a high and stable gate-source voltage threshold $V_{GS(th)}$ is also an important parameter for operation robustness. SiC MOSFET with such characteristics can directly use existing high-speed IGBT gate driver IC's. ${\bullet}$ The linear voltage drop characteristics of SiC MOSFET will bring lower conduction loss averaged over full AC cycle compared to similarly rate IGBT. Lower switching loss enable higher switching frequency. Using package with auxiliary source terminal for gate driving will further reduce switching losses. Dynamic characteristics can fully controlled by simple gate resistors. ${\bullet}$ The low switching losses characteristics of SiC MOSFET can substantially reduce power losses in high switching frequency operation. Significant power loss reduction is also possible even at low switching frequency and low switching speed. in T-type 3-level topology, SiC MOSFET solution enable three times higher switching freqeuncy at same efficiency.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.174-174
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• 2014

Memristor devices are one of the most promising candidate approaches to next-generation memory technologies. Memristive switching phenomena usually rely on repeated electrical resistive switching between non-volatile resistance states in an active material under the application of an electrical stimulus, such as a voltage or current. Recent reports have explored the use of variety of external operating parameters, such as the modulation of an applied magnetic field, temperature, or illumination conditions to activate changes in the memristive switching behaviors. Among these possible choices of signal controlling factors of memristor, photon is particularly attractive because photonic signals are not only easier to reach directly over long distances than electrical signal, but they also efficiently manage the interactions between logic devices without any signal interference. Furthermore, due to the inherent wave characteristics of photons, the facile manipulation of the light ray enables incident light angle controlled memristive switching. So that, in the tautological sense, device orienting position with regard to a photon source determines the occurrence of memristive switching as well. To demonstrate this position controlled memory device functionality, we have fabricated a metal-semiconductor-metal memristive switching nanodevice using ZnO nanorods. Superhydrophobicity employed in this memristor gives rise to illumination direction selectivity as an extra controlling parameter which is important feature in emerging. When light irradiates from a point source in water to the surface treated device, refraction of light ray takes place at the water/air interface because of the optical density differences in two media (water/air). When incident light travels through a higher refractive index medium (water; n=1.33) to lower one (air; n=1), a total reflection occurs for incidence angles over the critical value. Thus, when we watch the submerged NW arrays at the view angles over the critical angle, a mirror-like surface is observed due to the presence of air pocket layer. From this processes, the reversible switching characteristics were verified by modulating the light incident angle between the resistor and memristor.

• Journal of Power Electronics
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• 제10권6호
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• pp.749-761
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• 2010

The switching frequency of a power device is a very important parameter in the design of a parallel active power filter (PAPF), but so far, very little discussion has been conducted on it in a quantitative manner in previous publications. In this paper, an extensive analysis on the effects of the switching frequency on the performance of a PAPF is made, and a specification of the switching frequency values with different compensation results is presented. A first-order inertia element and a second-order oscillation element are considered as approximate models of a PAPF, respectively. The compensation characteristic for each order of harmonic current is obtained at different switching frequencies. Then, the THDs of each model for the system loads of a rectifier with resistance and inductance loads are proposed. The compensation results of a PAPF controlled as a first-order inertia element are better than those of a PAPF controlled as a second-order oscillation element. With two types of system loads which are rectifier with resistance and inductance loads and rectifier with resistance, inductance and capacitance loads, the THDs of the source current after compensation are presented with different switching frequencies. The compensation characteristics for the most widely used digital control system are investigated. The situation with an analog control is the theoretical characteristic and it is the best situation. The compensation characteristic of the digital control is worse than the compensation characteristic of the theoretical characteristic. Based on these analyses, the specifications of compensation characteristics with different switching frequencies are quite straightforward. Finally, a practical design example is studied to verify the application.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.332-335
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• 1990

There are several methods in controlling resonant converters to regulate the output with low switching losses. In this paper, Pulse-width modulation method or current controlled method is applied to regulate the output with low switching losses. In digital implementation of resonant converter systems, the speed of the applied processor is very critical since the switching frequency is very high. Thus the various possible candidates of microprocessors are evaluated for the implementation of resonant converter systems. Then too design methods and techniques are desioribed when single chip processor is used to simplify hardware requirements.