• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권10호
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• pp.492-499
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• 2002

This paper presents the method for an estimation of discharge current waveform in short gap discharge by radiated electromagnetic fields. The method of current waveform estimation is to use the one antenna method (single field method) with a measured electric or magnetic field at given field point by a time domain antenna. In order to verify the availability of the estimation theory, the discharge current waveform estimation was performed by one antenna methods using the measured electric fields of Wilson & Ma and compared with experiments. In addition diagnosis technique for power equipments is able to prevent from large accidents by finding signs of tile accidents before they happen. From the results of the estimation of discharge current, we have a possibility for the application of insulation diagnosis technique for power equipments using S$F_6$ gas. From this point of view, this paper simulated discharge progress and partial discharge by using needle-plan electrodes system in S$F_6$, studied the distribution of frequency spectrum of the radiated electromagnetic waves using a biconical antenna and a spectrum analyzer. From the experimental results of this study, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting Partial discharge and estimating discharge progress in S$F_6$ could be Possible.

• 전기학회논문지
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• 제57권11호
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• pp.1970-1975
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• 2008

Critical current of the superconducting machines is limited by the magnetic field. When the magnetic field is not uniform, it is difficult to estimate the magnetic field and the critical current. This paper proposed a method for the estimation of the magnetic field and the critical current of the HTS pancake windings which can be used to generate the high field magnet. A parameter which was needed to calculate the critical current of a BSCCO magnet with 10 pancake windings was obtained by the experiment. Test which was carried out by using single pancake winding and magnet consisting of 10 pancake windings shows the proposed method can be an effective method for the estimation of the critical current of pancake windings.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권6호
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• pp.402-407
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• 2004

This paper proposed a new speed sensorless control method for AC servo motor, which is based on the current observer. Recently, the study in the estimation using a observer is being widely progressed. In order to prove the superiority of the current observer, we made a comparison between the simulation using current observer and that using Luenberger observer. And also, a comparative experiment of the speed control of the AC servo motor using a sensor and using current observer has been executed. The experiment result shows that the estimation using current observer is superior to the estimation using Luenberger observer or to the speed response using a sensor.

• 전자공학회논문지S
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• 제35S권2호
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• pp.146-156
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• 1998

Thispapr proposes hybrid navigation parameter estimation using sequential aerial images. The proposed navigation parameter estimation system is composed of two parts: relative position estimation and absolute position estimation. the relative position estimation recursively computes the current velocity and absolute position estimation. The relative position estimation recursively computes the current velocity and position of an aircraft by accumulating navigation parameters extracted from two succesive aerial images. Simple accumulation of parameter values decreases reliability of the extracted parameters as an aircraft goes on navigating. therefore absolute position estimation is required to compensate for position error generated in the relative position step. The absolute position estimation algorithm combining image matching and digital elevation model(DEM) matching is presented. Computer simulation with real aerial image sequences shows the efficiency of the proposed hybrial algorithm.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.286-289
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• 2000

from the viewpoint of model-based current control it is indispensable to use the accurate system parameters for the high control performance. This paper adopts the Least-Squares algorithm as a parameter estimation scheme because it has the fast convergence rate and the low sensitivity to noises. in case of the PI current controller with high gains the simulation results show that the adopted estimation scheme can be successfully applied to PWM converters and also show that the control performance can be improved by using the estimated parameters.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.149-152
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• 1998

From the viewpoint of model-based current control, it is indispensable to use the accurate system parameters for the high control performance. This paper adopts the Least-Squares algorithm as a parameter estimation scheme because it has the fast convergence rate and the low sensitivity to noises. In case of the intelligent current controller with delay compensator, the simulation results show that the adopted estimation scheme can be successfully applied to PWM converters and also show the improved control performance in the estimated parameters.

• Journal of Power Electronics
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• 제18권1호
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• pp.300-308
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• 2018

An online estimation method for wireless power transfer (WPT) systems is presented without using any measurement of the secondary side or the load. This parameter estimation method can be applied with a controlling strategy that removes both the receiving terminal controller and the wireless communication. This improves the reliability of the system while reducing its costs and size. In a wireless power transfer system with an LCCL impedance matching circuit under a rectifier load, the actual load value, voltage/current and mutual inductance can be reflected through reflected impedance measuring at the primary side. The proposed method can calculate the phase angle tangent value of the secondary loop circuit impedance via the reflected impedance, which is unrelated to the mutual inductance. Then the load value can be determined based on the relationships between the load value and the secondary loop impedance. After that, the mutual inductance and transfer efficiency can be computed. According to the primary side voltage and current, the load voltage and current can also be detected in real-time. Experiments have verified that high estimation accuracy can be achieved with the proposed method. A single-controller based on the proposed parameter estimation method is established to achieve constant current control over a WPT system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.150-156
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• 1996

Static variations of cutting forces are estimated using spindle motor current. Static sensitivity of spindle motor current is higher than feed motor current. The linear relationship between the cutting force and RMS value of the spindle motor current is obtained. Using cutting force estimation, tool overload in milling process can be well detected, and cutting force is regulated at a constant level by feedrate adaptive control.

• 전력전자학회논문지
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• 제8권2호
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• pp.173-179
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• 2003

본 논문은 3상 PWM 컨버터의 커패시터의 용량을 온라인으로 추정하는 새로운 기법을 제안한다. 무부하 상태의 PWM 컨버터에 저주파수의 입력전류를 주입하면 직류링크단에 이에 대응되는 리플전압이 발생된다. 직류링크단의 리플전압과 전류를 검출하여 커패시터의 용량을 계산한다. 제안된 방법에 의해 계산된 커패시터의 용량의 추정오차는 2% 이내이다.

• 조명전기설비학회논문지
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• 제29권7호
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• pp.38-46
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• 2015

This paper propose a variable parameter estimations for variable over current load of five-phase squirrel-cage induction motor(IM) to servo control system. In order to high performance control of AC motor using a field oriented control(FOC) and direct torque control(DTC) algorithm, there are required precise motor parameters for slip calculation, flux observer, controller gain, torque command of current components, rotor position, speed estimation, and so on. We are suggest a analyzed estimation results of the motor parameters that developing five-phase squirrel-cage IM have a stator of concentrated winding for experimental within variable over current load at rated input frequency. There are results of stator winding measurement, no-load test, locked-rotor test, variable over current load test, and estimated parameters of equivalent circuits using manufactured experimental apparatus by IEEE Standard Test Procedure for Polyphase Induction Motors and Generators 112-2004.