• 전기전자학회논문지
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• 제24권1호
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• pp.170-177
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• 2020

본 논문은 HF/LF 변조 방법을 적용한 ANPC (active neutral point clamped) 인버터의 스위치 개방 고장에 대응하기 위한 허용 제어 방법을 제안한다. 기존 Si 기반 인버터에 비해 SiC MOSFET과 Si IGBT로 구성된 ANPC 인버터는 시스템의 효율이 높고 출력 품질이 우수하다. HF/LF 변조는 커뮤테이션 루프를 줄일 수 있어 MW 급 대용량 인버터를 위해 사용되는 변조 기법이다. MW 급 인버터의 스위치 개방 고장은 부하에 심각한 손상을 입히며, 인버터가 동작을 멈출 경우 막대한 경제적 손실을 야기한다. 제안하는 스위치 개방 고장의 허용 제어 기술은 ANPC 인버터의 지속적인 운전을 가능하게 하며 신뢰성을 향상 시킨다. 제안하는 기법의 성능은 시뮬레이션 결과를 통해 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.368-370
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• 2005

Superconducting fault current limiter (SFCL) provides the effect such as enhancement in power system reliability due to limiting fault current in a few miliseconds. The flux-lock type SFCL among various type SFCLs consists of two coils wound on the same iron core and a component using the YBCO thin film. In the SFCL, operation characteristics can be controlled by adjusting the inductances and the winding directions of the coils. In this paper, we investigated the various fault current limiting characteristics according to the voltage level. To analyze the current limiting performance, we compared operational characteristics on the subtractive polarity winding direction on in case of open-loop iron core.

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.110-113
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• 2002

The high-tc superconducting fault current limiters (SFCL) are studied worldwide to be classified as resistive type or inductive type such as magnetic shielding type and dc reactor type. This Paper deals with an open core type SFCL, a kind of magnetic shielding type SFCL. We manufactured a 30 kVA open core type SFCL. It was modified from the old one with a rated power of 8 kVA. We stacked four superconducting tubes as magnetic shielding material and used the same primary winding as the old one. The experiments were performed with a maximum source voltage of 1 kV. The results show that the fault current in the source voltage of 1 kVrms was reduced to be about 105 Apeak, which was calculated to be about 22 % of the fault current in the system without an SFCL.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.74-76
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• 2019

This paper proposes an open-switch fault tolerant strategy based on the model predictive control for a full bidirectional switches indirect matrix converter (FBS-IMC). Compared to the conventional Indirect Matrix Converter (IMC), the FBS-IMC can provide healthy current path when open-switch fault is occurred. To keep the continuous operation, the fault tolerant strategy is developed by means of reversing the DC-link voltage polarity regardless of the faulty switch location in the rectifier or inverter stage. Therefore, the proposed control strategy can maintain the same input and output performances during the faulty condition as the normal condition. The simulation results are given to verify the effectiveness of the proposed strategy.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.190-199
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• 2014

In the last years, fault problem in power electronics has been more and more investigated both from theoretical and practical point of view. The fault problem can cause equipment failure, data and economical losses. And the analyze system require to ensure fault problem and also rectify failures. The current errors on these faults are applied for identified type of faults. This paper presents technique to detection and identification faults in three-phase voltage source inverter (VSI) by using time-frequency distribution (TFD). TFD capable represent time frequency representation (TFR) in temporal and spectral information. Based on TFR, signal parameters are calculated such as instantaneous average current, instantaneous root mean square current, instantaneous fundamental root mean square current and, instantaneous total current waveform distortion. From on results, the detection of VSI faults could be determined based on characteristic of parameter estimation. And also concluded that the fault detection is capable of identifying the type of inverter fault and can reduce cost maintenance.

• 한국산학기술학회논문지
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• 제16권10호
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• pp.6666-6672
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• 2015

전력 케이블의 고장에 대한 위치를 검출하기 위한 다양한 반사파 계측법들이 연구되고 있다. 하지만 대부분 관련 연구들이 시뮬레이션과 실험실에서의 성능 검증이 이루어지고 있고, 실제 현장과 비슷한 조건에서의 연구는 실증 시험장의 부재로 인해 이루어지지 못하고 있다. 따라서 본 논문에서는 케이블 고장 검출 장치의 표준화된 성능 시험과, 장비 운영 교육을 위한 실증 시험장을 설계 및 구축하였다. 구축된 실증시험장에서는 100m, 200m 거리에서 단선, 합선, 반단선, 접촉 불량 고장을 발생시켰고 최대 거리 측정 시험을 위해 1km 케이블을 설치하였다. 이러한 실증시험장은 향후 케이블 고장 검출 기술의 개발과 표준화, 그리고 장비 성능 검증 및 인증 시험 등을 위해 활용될 수 있을 것이다.

• 한국산업융합학회 논문집
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• 제25권6_2호
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• pp.1003-1008
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• 2022

This paper proposes a method related to fault tolerance operation and characteristic analysis of asymmetric 6-phase permanent magnet synchronous motor. In general, motor drive systems with multi-phase structures can be continuously operated despite a reduction of power and speed by using a phase changeover or control techniques according to the failures. As a result, it is widely used in industrial fields such as aviation and defense, which require high efficiency and high reliability. In this paper, the second order ripple of the electrical fundamental freuqnecy occurs in the dq-axis currents of the synchronous coordinate system through mathematical analysis according to the switch open of the dual 3-phase inverter. Therefore, the fault tolerant operation method is presented by applying the fault detection method with a constant cycle for continuous operations. The effectiveness of the proposed fault tolerance operation method is verified through the several experiments.

• 전자공학회논문지A
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• 제32A권12호
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• pp.198-208
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• 1995

BiCMOS circuit consist of CMOS part which constructs logic function, and bipolar part which drives output load. Test to detect stuck-open faults in BiCMOS circuit is important, since these faults do sequential behavior and are represented as transition faults. In this paper, proposes a method for efficiently detecting transistor stuck-open faults in BiCMOS circuit by transforming them into slow-to=rise transition and slow-to-fall transition. In proposed method, BiCMOS circuit is transformed into equivalent gate-level circuit by dividing it into pull-up part which make output 1, and pull-down part which make output 0. Stuck-open faults in transistor are modelled as transition fault in input line of gate level circuit which is transformed from given circuit. Faults are detceted by using pull-up part gate level circuit when expected value is '01', or using pull-down part gate level circuit when expected value is '10'. By this method, transistor stuck-open faults in BiCMOS circuit are easily detected using conventional gate level test generation algorithm for transition fault.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.292-297
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• 2004

The conventional computerized numerical controller (CNC) of machine tools has been increasingly replaced by a PC-based open architecture CNC (OAC) which is independent of the CNC vendor. The OAC and machine tools with OAC led the convenient environment where it is possible to implement user-defined application programs efficiently within CNC. Tis paper proposes a method of operational fault cause diagnosis which is based on the status of programmable logic controller (PLC) in machine tools with OAC. The operational fault is defined as a disability state occurring during normal operation of machine tools. The faults are occupied by over 70% of all faults and are also unpredictable as most of them occur without any warning. Two diagnosis models, the switching function (SF) and the step switching function (SSF), are propose in order to diagnose the fault cause quickly and exactly. The cause of an occurring fault is logically diagnosed through a fault diagnosis system (FDS) using the diagnosis models. A suitable interface environment between CNC and develope application modules is constructed in order to implement the diagnostic functions in the CNC domain. The diagnosed results were displayed on a CNC monitor for machine operators and provided to a remote site through a web browser. The result of his research could be a model of the fault cause diagnosis and the remote monitoring for machine tools with OAC.

• 전력전자학회논문지
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• 제18권2호
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• pp.199-204
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• 2013

Recently, the demand for fuel efficient electric vehicles (EVs) and hybrid electric vehicles (HEVs) has been growing globally. Due to the increased number of switching devices in the electrified vehicles, the probability of the semiconductor device failure is much higher than in other application areas. A sudden failure in one of the power switches and insufficient power management ability in the systems not only decreases system performance, but also leads to critical safety problems. In this paper, novel switch open circuit fault detection method is proposed, and the proposed approach is verified by experiments.