• Journal of Power Electronics
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• 제16권6호
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• pp.2327-2337
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• 2016

The mode-switching control of transient process is important to grid-connected 400 Hz solid-state power supply systems. Therefore, this paper analyzes the principle of on-grid and islanding operation of the system with or without local loads in the grid-connected process and provides a theoretical study of the effect of different switching sequences on the mode-switching transient process. The conclusion is that the mode switch (MS) must be turned on before the solid-state switch (STS) in the on-grid process and that STS must be turned off before the MS in the off-grid process. A strategy of mode-switching smooth control for transient process of the system is proposed, including its concrete steps. The strategy utilizes the average distribution of peak currents and the smooth adjustment of peak currents and phases to achieve a no-shock grid connection. The simulation and experimental results show that the theoretical analysis is correct and that the method is effective.

• 한국항해학회지
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• 제21권3호
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• pp.75-81
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• 1997

현재 자동차나 선박등에 사용하는 직류모터 속도 제어용 스위칭 소자는 스위칭 과전압으로 인하여 때때로 손상되거나 오작동을 일으키기쉽다. 본논문은 dc 모터 제어용 반도체 스위칭소자의 내성특성을 개선한 것이다. 이를 위하여, 먼저 저전압 보호소자인 비리스터나 제너 다이오드 등 가운데에서 스위칭 과전압에 대해 내성을 갖는 이상적인 소자를 선택하기 위해 과전압 보호자의 등가회로를 분석 하였다. 나아가서 국제규정에서 정의된 의사 과전압 파형의 적절한 선택, 스위칭 소자의 손상과정과 손상원인을 규명하고, 순시과전압 전류의 변화에 따른 각각의 임피던스 조건을 고려하여 직류모터 제어용 반도체 스위칭 소자의 내성특성 개선하였다.

• Journal of Power Electronics
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• 제18권6호
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• pp.1901-1911
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• 2018

This study presents a circuit model for simulating the switching transients of insulated-gate bipolar transistors (IGBTs) with inductive load switching. The modeling approach used in this study considers the behavior of IGBTs and freewheeling diodes during the transient process and ignores the complex semiconductor physics-based relationships and parameters. The proposed circuit model can accurately simulate the switching behavior due to the detailed consideration of device-circuit interactions and the nonlinear nature of model parameters, such as internal capacitances. The developed model is incorporated in an IGBT loss calculation module of an electromagnetic transient simulation program to enable the estimation of switching losses in voltage source converters embedded in large power systems.

• 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.

• 대한전자공학회논문지
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• 제12권4호
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• pp.15-20
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• 1975

원자로의 출력을 초기상태에서 요구표적 상태로 증가시켜 주는 과도기간중 출력의 Overshoot가 생기는데 이 Overshoot에 구속조건을 두는 것은 원자로를 제각함에 있어 안전사 매우 중요하다. 따라서 출력이 요구 최대허용 구동영역을 넘지 않도록 반응도를 조절하면서 초기값(no, co)에서 최종같인 요구값(2no,2co) 또는 (1. 5no,1.5co)로 출력을 증가시키는데 최대원리(Maximum principle)를 적용하였다. 그리고 이때의 스위청점, 스위청시간 및 최적제각 반응도를 구하였다. The power overshoot is rises in the output during the transient period when the output of nuclear reactor is increased from the initial state to the desired target state and certain amount of constraint on power level is of primary importance for safety control of nuclear reactor. Therefore, the maximum principle is applied to this process control in transfering its power from the initial state(no, co) to the final target state(2no, 2co or 1.5no, 1.5co), adjusting the reactivity so that its overshoot is limited within the allowable constraint required. In this case, the switching points, switching times, optimal lima and optimal control reactivity are calculated.

• 전기학회논문지
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• 제64권1호
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• pp.196-200
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• 2015

The switching noise in the power electronics of the power conversion equipment (Power Conditioning System) for large energy storage devices are generated. Since the burst-level transient noise from being generated in the power system at a higher power change process influences the control circuit of the low voltage driver circuit. Noise may cause the malfunction of the control device even if no dielectric breakdown leads to a control circuit. To overcome this, this paper proposes the installation of an additional nano-surge protection device on the power supply DC output circuit of the battery management unit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.503-505
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• 1995

The surge arrester plays a vital role in the protection of substation against transient overvoltages resulting from lightning surges and system switching operations. The proper selection and application of the surge arrester is an integral part of the process of substation equipment insulation level selection. The paper outlines the basic consideration in modeling the lightning stroke, the surge arrester, and the system to be protected. The paper discusses the results of various cases simulated using the alternative transient computer program to evaluate the separation effects.

• Transactions on Electrical and Electronic Materials
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• 제17권3호
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• pp.172-177
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• 2016

Miller feedback compensation is introduced in a low dropout regulator (LDO) in order to obtain a capacitor-free regulator and improve the fast transient response. The conventional LDO has a limited bandwidth because of the large-size output capacitor and parasitic gate capacitance in the power MOSFET. In order to obtain a stable frequency response without the output capacitor, LDO is designed with resistor-capacitor (R-C) compensation and this is achieved with a connection between the gain-stage and the power MOS. An R-C compensator is suggested to provide a pole and zero to improve the stability. The proposed LDO is designed with the 0.35 μm CMOS process. Simulation testing shows that the phase margin in the Bode plot indicates a stable response, which is over 100^o. In the load regulation, the transient time is within 55 μs when the load current changes from 0.1 to 1 mA.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.406-411
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• 1993

A variable structure control scheme that can be applied to the process with input/output delays are proposed and its control performances are evaluated. The proposed VSCS, which is an output fedback scheme, comprises an integrator for tracking the setpoint and the Smith predictor for compensating the effects of time delay. With The VSCS, the robustness against the parameter variations and external disturbances can be achieved even when the controlled process includes I/O delays. And the desired transient response is obtained by simple adjustment of the coefficients of the switching surface equation.

• 대한전기학회논문지
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• 제43권7호
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• pp.1158-1168
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• 1994

A variable structure control scheme(VSCS) with sliding mode that can be applied to the process with input/output(I/O) delay is proposed and its control performances is evaluated. The proposed VSCS with and output feedback scheme comprises a variable structure controller, a servo dynamic for tracking the set-poing, and a Smith predictor for compensating the effects of time delay. The robustness against the parameter variations and external disturbances can be achieved by the proposed VSCS even when the controlled process includes I/O delay. And the desired transient response is obtained by simple adjustment of the coefficients of the switching surface equation.