• Title/Summary/Keyword: Current measurement

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New Sensorless Algorithm for SRM Based on Initial di/dt Measurement of Excited Phase Current (여자상의 초기 전류증가율 측정에 의한 Switched Reluctance Motor의 Sensorless 알고리즘)

  • Lim, Jun-Young;Deshpande, Vijay. V.;Shin, Doo-Jin;Oh, Jae-Yoon;Kim, Jung-Chul
    • Proceedings of the KIEE Conference
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    • 1996.11a
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    • pp.302-304
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    • 1996
  • In this paper, a new algorithm for sensorless speed control of switched reluctance motor (SRM) is proposed. It is based on the measurement of initial rate of change of phase current. The initial rate of rise of phase current mainly depends up on the phase inductance at the time instant when the phase is excited. Therefore, the measurement of initial di/dt permits rotor position estimation, which is used to trigger the next phase. In the proposed technique, there is no need to generate additional current pulses when a phase is not excited. Therefore, this scheme does not introduce the unwanted braking torque. Also, only one current measurement is made every time a phase is excited. This reduces the computational load on the micro-controller and enhances the speed range of the sensorless drive. By using this scheme it is possible to implement the sensorless control of SRM using low cost micro-controller.

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Development of a Compensating Algorithm for an Iron-cored Measurement CT using Flux-magnetizing Current Curves and Voltage-core Loss Current Curves (자속-자화 전류 곡선과 전압-철손 전류 곡선을 이용한 측정용 철심 변류기의 보상 알고리즘 개발)

  • Kang, Yong-Cheol;Zheng, Tai-Ying;Kang, Hae-Gweon;Lee, Byung-Eun;Kim, Yong-Gyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.1849-1854
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    • 2009
  • This paper describes the design, evaluation and implementation of a compensating algorithm for an iron-cored measurement current transformer (CT) that removes the effects of the hysteresis characteristics of the iron-core. The exciting current resulting from the hysteresis characteristics of the core causes an error of the CT. The proposed algorithm decomposes the exciting current into the core loss current and the magnetizing current and each of them is estimated. The core loss current is calculated from the secondary voltage and the voltage-core loss current curve. The core flux linkage is calculated and then inserted into the flux-magnetizing current curve to estimate the magnetizing current. The exciting current at every sampling interval is obtained by summing the core loss and magnetizing currents and then added to the measured current to obtain the correct secondary current. The voltage-core loss current curve and flux-magnetizing current curves, which are different from the conventional curves, are derived in this paper. The performance of the proposed algorithm is validated under various conditions using EMTP generated data. The experimental test results of an iron-core type electronic CT, which consists of the iron-core and the compensation board, are also included. The results indicate that the proposed algorithm can improve the accuracy of the measurement CT significantly, and thus reduce the size and the cost of the CT.

A Study on the Measurement System for Alignment of Cylindrical Forging Die (원통형 단조금형의 정렬을 위한 측정시스템에 관한 연구)

  • Youn, Jae-Woong
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.18 no.1
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    • pp.83-89
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    • 2009
  • In most multi-stage forging processes, the die spotting process or alignment of punch and die depends on the manual operation. It results a very tedious and inefficient procedure, thus the proper measurement system is needed to improve productivity and accuracy. This paper proposes a measurement system for alignment of die and punch which has a cylindrical holder, and describes the system concepts using 3 eddy-current displacement transducers and precise measurement jig. In order to apply this measurement system to real situations, the measuring procedures and system calibration method, etc. are proposed. Finally, the accuracy and productivity of this measurement system are investigated in this paper.

Non-contact critical current measurement of superconducting coated conductor using Hall Probe (Hall Probe를 이용한 초전도선재의 비접촉 임계전류 측정 방법)

  • Kim, Ho-Sup;Oh, Sang-Soo;Lee, Nam-Jin;Ha, Dong-Woo;Baik, Seung-Kyu;Ko, Rock-Kil;Ha, Hong-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03b
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    • pp.12-12
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    • 2010
  • The hall probe measurement system was used to measure the critical current distribution of superconducting coated conductor. The system consists of reel to reel moving apparatus, 7 array hall probe, a rotary encoder and permanent magnet. The magnetic field profile across the width of superconducting coated conductor using Bean's critical state model was calculated. The effect of various parameters of the formulas on the magnetic field distribution and the effect of shape and size of artificial defects, which were formed on the surface of SmBa2Cu3O7-d(SmBCO) coated conductor using laser marking system, on the hall probe magnetic field signal of the hall probe measurement system was investigated.

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Cathodic Protection Behavior of Coastal Bridge Structure with Sacrificial Anode Cathodic Protection System (희생양극식 음극방식이 적용된 해안 교량 구조물의 방식거동)

  • Ha, Ji-Myung;Jin, Chung-Kuk;Jeong, Jin-A
    • Corrosion Science and Technology
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    • v.11 no.6
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    • pp.242-246
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    • 2012
  • This measurement represents the effectiveness of sacrificial anode cathodic protection (SACP) system in a coastal bridge structure. To verify the cathodic protection (CP) effect, the monitoring sensor (DMS-100) that could measure potential, corrosion rate, current, concrete resistivity, and temperature was embedded. The measurement conducted for three years after CP system was installed. Specifically, due to the fact that fresh water and sea water was repeated in the bridge structure, this bridge structure presented special CP behavior. Measurement factors were CP potential, CP current, concrete resistivity, and depolarization potential. In addition, visual inspection was also carried out. As a result of current and depolarization measurement, CP system was well activated in most piers.

Design and Implementation of High Power LED Junction Temperature Measurement Circuit (고출력 LED의 접합온도 측정회로 설계 및 구현)

  • Park, Chong-Yun;Yoo, Jin-Wan
    • Journal of Industrial Technology
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    • v.30 no.A
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    • pp.83-88
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    • 2010
  • Recently, the LED lighting is widely used to illumination purpose due to its high luminous efficiency and the long life time. However, the light power and lifetime is reduced by junction temperature increment of LED. So it is important to measure the junction temperature accurately. In this paper, we proposed a new design and implementation method of high power LED junction temperature measurement circuit. The proposed circuit has two current sources which are a driving current source and a measurement is verified by experiment, and the result shows that the proposed circuit is appropriate to practical use.

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A Study on the Characteristic and Rising Cause of Sheath Circulating Current by Analysis and Measurement (해석 및 측정을 통한 시스순환전류 특성 및 상승원인 검토)

  • Gang, Ji-Won;Yang, Hae-Won
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.10
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    • pp.525-533
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    • 2002
  • It is common to install multiple lines in the same route. Recently, excessive sheath circulating current was partially measured in underground cable systems of KEPCO. Especially, the installation type, unbalance section length between joint boxes and zero sequence current by distribution cable have an effect on the rising of sheath circulating current in the underground transmission system. If excessive current flows in sheath, sheath loss which is reduced the transmission capacity is produced. This paper describes the relation analysis of sheath circulating current and burying types. And also, a detailed analysis on rising cause and characteristic of sheath circulating current by considering various unbalanced conditions presents using analysis and measurement regarding cable systems which have the problem of excessive sheath circulation current.

Study on Development of the Isolation Resistance Measurement System for Hydrogen Fuel Cell Vehicle (수소연료전지자동차용 절연저항 측정시스템 개발에 관한 연구)

  • Lee, Ki-Yeon;Kim, Dong-Ook;Moon, Hyun-Wook;Kim, Hyang-Kon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.5
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    • pp.1068-1072
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    • 2011
  • Hydrogen Fuel Cell Vehicle(HFCV) is system that uses electrical energy of fuel cell stack to main power source, which is different system with other vehicles that use high-voltage, large-current. Isolation performance of this system which is connected with electrical fire and electrical shock is important point. Isolation resistance of electric installation is divided according to working voltage, it follows criterion more than $100{\Omega}$/VDC (or $500{\Omega}$/VAC) about system operation voltage in a hydrogen fuel cell vehicle. Although measurement of isolation resistance in a hydrogen fuel cell vehicle is two methods, it uses mainly measurement by megger. However, the present isolation resistance measurement system that is optimized to use in electrical facilities is unsuitable for isolation performance estimation of a hydrogen fuel cell vehicle because of limit of maximum short current and difference of measurement resolution. Therefore, this research developed the isolation resistance measurement system so that may be suitable in isolation performance estimation of a hydrogen fuel cell vehicle, verified isolation performance about known resistance by performance verification of laboratory level about developed system, and executed performance verification through comparing results of developed system by performance verification of vehicle level with ones of existing megger. Developed system is judged to aid estimation and upgrade of isolation performance in a hydrogen fuel cell vehicle hereafter.

Measurement and Analysis of Risk Voltages in a Grounding System (접지계에서 위험전압의 측정과 분석)

  • Jin, Chang-Hwan;Park, Dae-Won;Seo, Jae-Seok;Kil, Gyung-Suk;Gil, Hyeong-Jun
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.3099-3103
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    • 2011
  • In measurement of risk voltages; the step and touch voltage, the distance between the current electrode and the ground electrode recedes up to several hundred meters as the scale of grounding system increases. This paper dealt with the measurement method of risk voltage in a restricted space. The risk voltage was analyzed depending on the distance and the direction of the current electrode from the ground electrode in a $10[m]{\times}10[m]$ mesh grounding system. The average value of risk voltages measured at a point 20 [m] away from the current electrode was deviated below 5 [%] from that measured at 100 [m] point. Consequently, the evaluation of risk voltage of a large-scale grounding system buried in a spatially restricted place is available if the current electrode is installed in symmetry to the ground electrode.

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Device Development for Longshore Current Measurement and Model Test (연안류 추적 장치 개발 및 모형 실험)

  • Lee, Chung-Il
    • Journal of Environmental Science International
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    • v.23 no.11
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    • pp.1801-1805
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    • 2014
  • Longshore current is main transportation mean causing movement of bed load and suspended particle in coastal waters, and effective measurement method and suitable equipment for shallow water coastal environment where is frequently exposed to atmosphere. Measurement equipment for longshore drift was designed and miniature model was applied to Gyeongpo beach in May and June, 2014. The equipment consists of three main elements, spheroid outer casing, spheroid inner casing, observation module equipped with GPS. Gyroscope principle was applied to observation module, and GPS receiver always can be directed upwards. Miniature models were installed along Gyeonpo beach, and it was well to track the flow of longshore current. This research described the design and function of the equipment and results of field experiments.