• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.275-278
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• 2003

The pantograph contact can be disrupted due to irregularities in the motion. The pantograph detachment prohibits the current flow and makes the system uncontrollable. During the pantograph detachment period, the control error are accumulated by the integral property of the controller. The output of the controller, therefore, can be induced to be an extremely large value. When the pantograph is reattached, the extremely large output of the controllers causes a very high overshoot (or under-shoot) of the line current and the DC-link voltage. This work proposes a new method for detecting the pantograph bouncing conditions and designs a controller considering such conditions based on the pantograph bouncing detector.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.215-218
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• 2000

The windup phenomenon appears and degrades control performance when a controller with integrating action is used and the plant input is limited. An anti-windup integral -proportional(IP) controller is proposed for the variable-speed motor drives and it is experimentally applied to the speed control of a vector-controlled induction motor driven by a pulse width modulated (PWM) voltage source inverter(VSI). Although the operating conditions like motor load and speed command is changed under the limited plant input it is experimentally verified that the speed response has much improved performance such as no overshoot and fast settling time and the maximum plant input is also effectively utilized.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1727_1728
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• 2009

Nowadays DC-DC converter has been used widely in electronic production. It has a high requirement in wide input voltage, load variations, stability, providing a fast transient response and lower overshoot. However, it is not easy to be controlled because of its nonlinearity. In this paper, the nonlinear model of DC-DC converter is approximatedby four linear models and sub-controllers are designed by using the LMI guaranteeing the stability of the sub-systems at the same time. For the robust of the control system, an integral sliding mode control (ISMC) is applied together with LMI fuzzy controller. The proposed controller supports a fast and almost no overshooting transient response for the DC-DC converter control.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.183-186
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• 2007

This Paper presents a solution to control the Brushless DC Motor(BLDCM) in Hard Disk Drive(HDD) using the Linear Quadratic Regulator(LQR). Generally, The speed of BLDCM in HDD is controlled by the lead angle control or the input voltage control using PAM(Pulse Amplitude Modulation) etc. These control methods have speed overshoot in speed control and need the long time until BLDCM reaches at the steady state. In order to improve the performance, this paper present the PI speed controller using the LQR based on vector control and the rotor position detection methods at the space vector PWM inverter. The proposed methods are proved by the simulation and experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10B
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• pp.1464-1469
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• 2001

본 논문에서는 디지털 하이브리드 위상고정루프(Digital Hybrid Phase-Locked Loop, DHPLL) 주파수 합성기 구조에서 고 순도 스펙트럼과 초고속 스위칭 속도를 위한 설계기술을 제안한다. D/A 변환기 출력으로 전압제어발진기(Voltage Controlled Oscillator, VCO)를 구동하는 개 루프(open-loop) 구성 방식과 기존 위상고정루프(Phase Locked Loop, PLL)의 폐 루프(closed-loop) 구성 방식을 혼합한 하이브리드 구조의 주파수 합성기를 고려하여, 시스템 변수(개 루프 대역과 위상 여유)와 성능 파라미터(정착시간, 위상 잡음, 그리고 최대 오버슈트(Max. overshoot)의 관계를 연구하였다. 그리고 이 관계를 통해 스펙트럼 순도와 스위칭 속도를 향상시키기 위한 최적의 3가지 설계방안을 제시한다. 컴퓨터 시뮬레이션 결과, 주파수 스위칭 과정에서 발생하는 최대 오버슈트가 0.0991%이고 완전 정상상태 도달시간은 0.288msec이다. offset 주파수 10KHz에서 위상 잡음은 -128.15dBc이다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1644-1651
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• 1989

In this paper, a two-dimensional numerical analysis of HEMT's with gate length of 0.6um is performed. In this case, Control Volume Formulation method which has been used in the analysis of heat transfer and fluid flow is used as a numerical method. As a mobility model, empirical formula including the velocithy overshoot phenomena is used instead of two-piece mobility model. The results obtained from this numerical analysis(i.e., the region in which cahnnel is formed, the strength of electric field in the channel, the distribution of potential, and the distribution of electron concentration etc.)are in good agreement with the previous analytic results. And our results also show the parasitic MESFET's operation in the range of the high gate voltage.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.75-78
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• 1989

In this paper, A last time delay damper is presented for HB ( HyBrid ) step motor, which has large oscillation characteristics.The design objective is to develop a cost-effective and good-performance damper that would be applyed to HB step motor / driver system without the addition of transducer that would add a weight, size and cost to the system. The Back EMF signal which is recovered from current and voltage signal is used for the measuring the rotor position. It would be possible to get more accurate delay time for the motor driver system. It is proved that the maximum overshoot can be reduced to 13% at stopping through experiment.

• ETRI Journal
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• v.17 no.4
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• pp.1-12
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• 1996

A novel body-tied silicon-on-insulator(SOI) n-channel metal-oxide-semiconductor field-effect transistor with grounded body electrode named GBSOI nMOSFET has been developed by wafer bonding and etch-back technology. It has no floating body effect such as kink phenomena on the drain current curves, single-transistor latch and drain current overshoot inherent in a normal SOI device with floating body. We have characterized the interface trap density, kink phenomena on the drain current ($I_{DS}-V_{DS}$) curves, substrate resistance effect on the $I_{DS}-V_{DS}$ curves, subthreshold current characteristics and single transistor latch of these transistors. We have confirmed that the GBSOI structure is suitable for high-speed and low-voltage VLSI circuits.

• Journal of Power Electronics
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• v.11 no.1
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• pp.45-50
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• 2011

This paper proposes a method for comparing and evaluating anti-windup proportional-integral (PI) control strategies. The so-called PI plane is used and its coordinate is composed of the error and the integral state. In addition, an anti-windup PI controller with integral state prediction is proposed. The anti-windup scheme can be easily analyzed and evaluated on the PI plane in detail. Representative anti-windup methods are experimentally applied to the speed control of a vector-controlled induction motor driven by a pulse width modulated (PWM) voltage-source inverter (VSI). The experimental results compare the anti-windup PI controllers. It is empathized that the initial value of the integral state at the beginning of the linear range dominates the control performance in terms of overshoot and settling time.

• Transactions on Electrical and Electronic Materials
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• v.11 no.4
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• pp.178-181
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• 2010

An automotive IC voltage regulator which consists of one-chip based on a metal-oxide semiconductor field effect transistor (MOSFET) is investigated experimentally with three types of packaging. The closed type is filled with thermal silicone gel and covered with a plastic lid on the MOSFET. The half-closed type is covered with a plastic case but without thermal silicone gel on the MOSFET. Opened type is no lid without thermal silicone gel. In order to simulate the high temperature condition in engine bay, the operating circuit of the MOSFET is constructed and the surrounding temperature is maintained at $100^{\circ}C$. In the overshoot the maximum was mainly found at the half-closed packaging and the magnitude is dependent on the packaging type and the surrounding temperature. Also the impressed current decreased exponentially during the MOSFET operation.