• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.207-208
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• 2006

분자선(分子線)에피택시법(法)으로 성장(成長)한 ZnO 산화물반도체(酸化物半導體)를 이용(利用)하여 제작(製作)한 쇼트키배리어 다이오드에 대하여 자외선(紫外線) 광(光)센서로서의 광특성(光特性)을 조사(調査)한다. 첫째, 백색광(白色光) 조사시(照射時) 포화전류치(飽和電流値)가 100배(培) 이상(以上) 증가(增加)하는 광(光)여기 특성(特性)을 나타낸다. 둘째, 조사(照射)하는 �셈� 파장(波長)에 대하 390nm의 차단장파장(遮斷長波長)을 갖으며 195nm 이상(以上)의 밴드폭을 갖는 파장감도특성(波長感度特性)을 나타낸다. 셋째, 자외선(紫外線)에 대해 0.36msec의 시정수(時定數) 갖는 것으로 평가(評價)된다. 따라서, ZnO 산화물반도체(酸化物半導體)는 향후(向後) 자외선(紫外線) 광(光)센서소자의 재과(材科)로서 기대(期待)되어진다.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.493-496
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• 1998

Several sensorless vector control methods of induction motor have been proposed, but these methods don't have the satisfying performance to the change of the rotor time constant. Therefore, this paper proposes the sensorless vector control method which estimates the rotor speed using MRAS and compensates the rotor time constant using current error feedback at the same time. This method can guarantees the accurate performance of sensorless vector control while the rotor speed and the rotor time constant are changing. This method is verified by computer simulation using SIMULINK in MATLAB.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.365-373
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• 1996

This paper presents the effects of rotor time constant variation and the on-line tuning algorithm of the rotor time constant. If the value of the rotor time constant is set incorrectly, the IFOC (Indirect Field Oriented Control)scheme exhibits deteriorated performance according to the wrong slip command. These variation effects of the rotor time constant are caused by the slip calculator where it is known that the rotor time constant play an important role in the aligned rotor flux. Using the two torque angles (stationary torque angle, rotating torque angle), the variation of the rotor time constant is identified, and the rotor time constant of the controller is tuned to the proper value of the machine. As the result, with the proposed algorithm, the dynamics of the deteriorated IFOC system, where the rotor time constant is varied, is improved. For the purpose of the validity of this proposed algorithm, the computer simulations and the experiments have been performed and the explanation of the results is presented. (author). refs., figs., tab.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1027-1029
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• 1998

The method of building the system state matrix described here is the direct method which constructs elements of state matrix directly by the algebraic expressions from the machine data with time constants. From this method, it is reasonable to confirm the structure of state matrix and the relation of submatrices and elements efficiently. In this paper the interrelationship of submatrices of system matrix is investigated and a constitution of system matrix considering time constants.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1039-1041
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• 2000

To obtain a high performance in a vector controlled induction machine, it is essential to know the instantaneous position of the rotor flux which depends on the rotor time constant. But the rotor time constant mainly varies due to the temperature rise in the motor winding, so real time compensating algorithm is necessary. This paper proposes that it uses short duration pulses added to the constant flux command current and then resultant torque command current produced by speed controller is utilized for the rotor resistance estimation. This method has advantages with a low computational requirement and does not require voltage sensors. The proposed method is proved by simulations.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.21-24
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• 2002

The vector control system of an induction motor is the high performance drive system to achieve the instantaneous torque control. The vector control system is greatly divided into the direct control, and the indirect control that the most widely is used, The indirect vector control needs the rotor time constant, which changes widely according to the temperature, frequency, and current amplitude. The incorrect time constant leads to the saturation of magnetic flux or under-excitation phenomena. As a result, that deteriorate the control performance. Therefore, in this paper, the effect of time constant variation is investigated and its on-line tuning algorithm is proposed. The time constant using the torque angles was calculated and that of the validity of algorithm proposed was proved through the computer simulation and the experiment.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.147-148
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• 2015

본 논문에서는 50kW 디젤발전기를 MATLAB/SIMULINK를 이용해 모델링 하였으며, 독립운전을 통해 배터리에 전력을 공급하는 시스템을 시뮬레이션 하였다. 독립운전에서의 디젤발전기 제어기는 주파수를 제어하는 조속기와 전압을 제어하는 여자기로 구성되어 있으며, 액추에이터와 디젤엔진 등은 응답 속도를 고려한 시정수를 갖는 시지연 함수로써 모델링하였다. 디젤발전기에서 CVCF 제어를 통해 BESS(Battery Energy Storage System)에 전력을 공급할 때, 디젤발전기와 BESS 측의 전압 특성을 분석하였다.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.14-16
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• 2004

A DC railway system has low feeder voltage, The remote fault current can be smaller than the current of load starting. So it is important to discriminate between the small fault current and the load starting current. The load starting current increases step by step but the fault current increases all at once. As for the load starting current, the time constant of load current at each step is much smaller than that of the fault current. To detect faults in DC railway systems, an algorithm using the time constant calculated by the method of least squares was presented. But, It have a weakness about harmonic to calculate time constant. So in this paper, new protection algorithm for DC railway systems using estimation of time constant based on fourier transform was presented.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2573-2575
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• 2001

아날로그 필터는 각종 시스템의 특히 입출력단에서 신호의 선택적 분리 및 잡음 특성을 개선하는 것으로 필수적인 구성체 이다. 아날로그 필터에는 여러 가지의 형태가 있으나 집적화가 가능하고 높은 주파수 영역에서도 사용이 가능한 Gm-C필터가 많이 연구되고 시스템에서 구현되어 지고 있다. 본 논문에서는 저주파에서 수백 MHz의 주파수 영역에서 동작이 가능한 아날로그 IC 필터인 Gm-C 필터의 새로운 튜닝구조를 제한 하였다.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.353-356
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• 1995

This paper proposes a simple identification method of the rotor time constant to solve the degradation of motor performance due to the difference between the rotor time constant of a controller and actual one in slip frequency type vector control scheme. The proposed method is based on rotor induced voltage equations and it is confirmed that immunity of the stator resistance thermal variation. The simulation results show that the proposed method suitably identifies the rotor time constant in steady state as well as in transient state.