• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.400-405
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• 2008

Motor is energy converting system to generate mechanical force from electrical power and there are various typed motors in home, office, factory, vehicles, aircraft, shipping, etc. Recently in compliance with performance and reliability and the applications of variable speed motors with invert driver are expanded. Almost high power inverter have IGBT and IGBT's fault cause motor system fault. If we can calculate and foresee troubles of IGBT, we can protect accident caused by motor system fault. In this paper, the deterioration test method of IGBT devices is proposed and the test results of proposed method are shown by evaluated equipment. The basic concept of proposed method is current-voltage characteristic curve test between drain and source of IGBT in open state. The applied voltage type is ramp and it is confirmed that the current-voltage curvet pattern of IGBT in open state represents IGBT's deterioration state.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.718-719
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• 2011

Lately, the demand for electrical power has been significantly increased. As a result a power transmission system has been improved. On the other hand fault current increased more than past. Superconducting fault current limiter (SFCL) is one of the solutions to limit fault current. However, SFCL's research has not advanced in a power transmission system fully. Therefore, we studied effect of SFCL in a power transmission system. The power distribution system is open-loop circuit, but a power transmission system is closed-loop system. Consequently, Fault current in a power transmission system is larger than fault current in a power distribution system. we exerimented a simple closed-loop power transmission system circuit.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2277-2287
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• 2015

In recent times, multilevel inverters are given high priority in many large industrial drive applications. However, the reliability of multilevel inverters are mainly affected by the failure of power electronic switches. In this paper, open-switch and short-switch failure of multilevel inverters and its identification using a high performance diagnostic system is discussed. Experimental and simulation studies were carried out on five level cascaded H-Bridge multilevel inverter and its output voltage waveforms were analyzed at different switch fault cases and at different modulation index values. Salient frequency domain features of the output voltage signal were extracted using the discrete wavelet transform multi resolution signal decomposition technique. Real time application of the proposed fault diagnostic system was implemented through the LabVIEW software. Artificial neural network was trained offline using the Matlab software and the resultant network parameters were transferred to LabVIEW real time system. In the proposed system, it is possible to precisely identify the individual faulty switch (may be due to open-switch (or) short-switch failure) of multilevel inverters.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2619-2627
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• 2009

비접지 배전계통에서 전체고장의 약 70%를 차지하는 지락고장 발생시에는 지락전류가 작아 검출이 어렵지만 고장상태로 전원 공급을 지속할 경우 사고 파급 및 기기 소손을 유발할 가능성이 있기 때문에 지락고장 처리는 매우 중요하다. 본 논문에서는 GPT(접지형 계기용 변압기, Ground Potential Transformer)에서 감지하는 영상전압 신호를 이용하여 고장선로를 검출하고, 비상시 연계선로를 이용하여 정전구역을 복구하기 위해 평상시 개폐기가 열려 있는 상태로 배전선로 사이를 연결하는 상시개방점을 이동하며 각 구간을 차례로 분리하면서 GPT 신호의 사라짐 여부를 감시하여 고장구간을 검출하는 방법을 제안한다. 고장구간 탐색 시 전체 정전이 없고, 고장구간 검출과 건전구간 복구가 동시에 가능하며 다양한 형태의 배전계통 구성에 적용 가능하다는 점에서 효율적이다. 본 논문에서 제안하는 고장처리 방법을 프로그램으로 개발하여 베트남 배전자동화 시범사업에 적용함으로써 알고리즘 및 프로그램의 적정성을 검증하였다.

• Journal of Power Electronics
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• 제12권1호
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• pp.24-32
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• 2012

Direct duty-ratio PWM schemes for continuous fault tolerant operation of matrix converter-fed motor drives are presented. The proposed method features simple modular modulation structure based on per output phase concept, which requires no additional modification on the normal modulation schemes for fault-tolerant applications. Realizations of fault-tolerant strategy applied to different system configurations are also treated to enhance the system flexibility. The proposed method can be effectively applied to treat the motor open phase fault and converter switching device failure. Simulation and experimental results show the feasibility and validation of the proposed strategies.

• 조명전기설비학회논문지
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• 제25권1호
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• pp.101-106
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• 2011

The failure of cooling system in Superconducting Fault Current Limiter(SFCL) increases the impedance of superconducting device, and due to malfunction of inner switches the SFCL opens the distribution system inadvertently when required to do so. In this paper, the ground fault and short circuit fault were classified as active failure and the open circuit fault was passive failure. A reliability model of SFCL considers the passive failure as well as active failure, and in the case study the reliability indices of distribution system are evaluated. It is possible that the reliability evaluation excluded passive failure makes the customers reliability seem so worse than it really was. Therefore, the reliability models of SFCL must include the active failure and passive failure together to evaluate the reliability of distribution system connected SFCL.

• Journal of Power Electronics
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• 제9권3호
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• pp.377-385
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• 2009

In this paper, a diagnosis method for switch open-circuit faults in three-phase PWM inverters is proposed, which employs support vector machine (SVM) as classifying method. At first, a discrete wavelet transform (DWT) is used to detect a discontinuity of currents due to the fault, and then the features for fault diagnosis are extracted. Next, these features are employed as inputs for the SVM training. After training, the SVM produces an optimized boundary which is used identifying the fault. Finally, the fault classification is performed online with instantaneous features. The experimental results have verified the validity of the proposed estimation algorithm.

• 전기학회논문지
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• 제64권3호
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• pp.498-504
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• 2015

This paper proposed an Spread Spectrum Time Domain Reflectometry (SSTDR) using time-frequency correlation analysis in order to have more accurate fault determination and location detection than classical SSTDR despite increased signal attenuation due to the long distance to cable fault location. The proposed method was validated through comparison with classical SSTDR methods in open- and short-circuit fault detection experiments of low-voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• Journal of Power Electronics
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• 제10권6호
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• pp.686-693
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• 2010

In this paper, a fault diagnosis method based on fuzzy logic for the three-parallel power converter in a wind turbine system is presented. The method can not only detect both open and short faults but can also identify faulty switching devices without additional voltage sensors or an analysis modeling of the system. The location of a faulty switch can be indicated by six-patterns of a stator current vector and the fault switching device detection is achieved by analyzing the current vector. A fault tolerant algorithm is also presented to maintain proper performance under faulty conditions. The reliability of the proposed fault detection technique has been proven by simulations and experiments with a 10kW simulator.

• Advances in Computational Design
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• 제8권3호
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• pp.255-271
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• 2023

The gear drive of a combat aircraft engine is responsible for power transmission to the different accessories necessary for the engine's operation. Incorrect power transmission can occur due to the presence of failure modes in the gears like bending fatigue, pitting, adhesive wear, scuffing, abrasive wear and polished wear etc. Fault diagnosis of the gear drive is necessary to get an early indication of failure of the gears. The present research is to develop an algorithm using different vibration signal processing techniques on industrial vibration acquisition systems to establish gear fault diagnosis architecture. The signal processing techniques have been used to extract various feature vectors in the development of the fault diagnosis architecture. An open-source dataset of other gear fault conditions is used to validate the developed architecture. The results is a basis for development of artificial intelligence based expert systems for gear fault diagnosis of a combat aircraft engine.