• Title/Summary/Keyword: 유도전동기

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Design optimization of the staking line for an electric fan blade using CFD (CFD를 이용한 선풍기 날개의 스태킹 라인 최적 설계)

  • Park, Seunghwan;Ryu, Minhyoung;Cho, Leesang;Cho, Jinsoo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.11
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    • pp.903-910
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    • 2014
  • Electric fans, which consist of axial blades, are operated by the induction motor. In this paper, the objective of this study is the performance improvement of the base model fan using the design optimization. In order to aerodynamic analysis, computational simulations are performed using commercial tool ANSYS-CFX ver. 14.5. And k-${\omega}$ SST turbulence model is used for the CFD analysis. The design variables are set up as sweep and lean angles. Volumetric flow rate and torque of the fan blades are fixed to objective function. The optimized model is shown the increment of the volumetric flow rate and the reduction of the torque compared with the base model. The experimental procedure is followed KS C 9301. CFD results and experimental results are fairly well matched.

Study on Influence of Rotor Temperature Variation on the Performance of Maximum Torque Per Amp Control Strategy (단위 전류당 최대 토크 제어기 성능에 미치는 로터 온도 변화의 영향에 대한 연구)

  • Kwon, Chun-Ki
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.11
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    • pp.3110-3114
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    • 2009
  • Rotor temperature variation is a significant issue in the design of induction motor controls. In the literature, numerous studies have mentioned significant performance degradation due to rotor temperature variation unless it is taken into account. However, those studies have mainly focused on field-oriented control in terms of tracking performance. There was little research about the influence of rotor temperature variation on performance particularly in the case of optimal controls such as maximum torque per amp (MTPA) control strategy. This work investigates how to affect the performance of maximum torque per amp (MTPA) control strategy as rotor temperature varies in time. To this end, investigation was carried out in two ways to see whether the objective of MTPA control strategy is achieved regardless of rotor temperature variation. It is to produce a desired torque with the minimum possible stator current at the same time. Laboratory experiment shows that tracking performance and maximum torque per amp condition is significantly affected by rotor temperature variation as rotor temperature varies, thus ending up with performance degradation of MTPA control.

Design of the PD Controller in the I-PD Control System for Position Control (위치제어를 위한 I-PD제어계에서 PD제어기의 설계)

  • Kim, Sung-Dae
    • Journal of the Institute of Convergence Signal Processing
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    • v.10 no.4
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    • pp.262-266
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    • 2009
  • Since high speed and precision control shoud be satisfied in the position control system, the DC servo motor with easy control and satisfactory response characteristic is used. The various studies of position control techniques have been proposed in order to improve the control performance in the position control system. In this paper, the design method for a position control is suggested for constructing the PD controller in I-PD control system. The coefficients of PD controller in the I-PD control system are determined by using the transfer function which is normalized. Stability and root conditions of the system are derived from mathematical technique. From the result of computer simulation in I-PD control system by applying this control technique, is investigated by the method of proposed design the effectiveness of system response characteristic for input and disturbance.

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A Study on the Reversible SCR Servo Amplifier (정역전이 가능한 SCR 서보증폭기에 관한 연구)

  • Ahn, B. W.;Park, S. K.
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.31 no.2
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    • pp.190-198
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    • 1995
  • Many industrial servo amplifiers employ power transister as output device. Thyristor converters are not adopted to drive servo motor, although thyristor is superior to power TR in power rating, noise immunity, price, and size. The reason is, thyristor has no ability of self turn - off. Here in this paper line commutation, in which thyristor is turned off naturally since cathode voltage is higher than anode as time goes by, is employed to turn on thyristor with a delicate sequence. We developed thyristor servo amplifier which does not cause any damage on thyristor because it is designed to prevent triggering the two SCRs in the same arm simultaneously. And it was made clearly how to trigger SCR without any power line shorting and also harmonic analysis is carried out with the aid of FFT analyzer and proved that it can be used even severe reactive load. The designed circuit operated as a good DC amplifier in conventinal servomotor and the results can be use as a position control system application.

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A Design of Dynamic Braking Resistor for Stationary Mode of Azimuth Driving Equipment for Multi-Function Radar (다기능 레이다 방위각 구동 장치의 정지 모드를 위한 제동저항 설계)

  • Byeol Han;Woo-Seok Oh;Myeong-Hwan Shin;Yeongsu Bak
    • Journal of IKEEE
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    • v.28 no.3
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    • pp.382-389
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    • 2024
  • In this paper, a design of dynamic braking resistor for stationary mode of azimuth driving equipment (ADE) for multi-function radar (MFR) is presented. The ADE carries out missions which is the rotation mode for all directions and the stationary mode for tracing a subject with standstill. The ADE has to transfer the operation mode in demand time from rotation mode to stationary mode for precise target tracing. During the transition with deceleration, it may cause the fault of input power device due to back-electromotive force (back-EMF) of PMSM with generator mode. To protect the power device, a design of dynamic braking resistor is essential for consuming back-EMF. This paper presents the development of dynamic braking resistor for consuming back-EMF of ADE with deceleration mode. The validity and effect of the design is verified using simulation results.

Experimental Study on the Natural Convective Heat Transfer Characteristics of Ferrofluid for Concentric Annuli under Rotating Magnetic Field (회전수 및 자기장강도 변화에 따른 이중원관내 자성유체의 자연대류 열전달 특성에 관한 실험적 연구)

  • Kim, Hyung-Jin;Seo, Jae-Hyeong;Kim, Dae-Wan;Lee, Moo-Yeon;Seo, Lee-Soo
    • Journal of the Korean Magnetics Society
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    • v.23 no.2
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    • pp.77-81
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    • 2013
  • The objective of this study is experimentally to investigate natural convective heat transfer characteristics of the ferrofluid for a concentric annuli under rotating magnetic field with variations of the revolution and the magnetic field strength. The rotating magnetic field was provided by induction motor with 6 poles and 3 phases and the revolution and the magnetic field strength were controlled by an inverter driver and a voltage meter, respectively. Temperatures of the inner pipe and the outer pipe in the tested concentric annuli were maintained at $30^{\circ}C$ and $25^{\circ}C$, respectively, during the test and the direction of the rotating magnetic field was a counterclockwise. As a result, the natural convective heat transfer characteristics of the ferrofluid for a concentric annuli were increased with the rise of the revolution and magnetic field strength due to the increased heat dissipation between hot side and cold side of the concentric annuli.

Analysis of Abnormal Signals for Induction Motor according to Operating Status of Fire Pumps (소방펌프의 운전상태에 따른 유도전동기의 이상 신호 분석)

  • Ku, Bonhyu;Kim, Doo-Hyun;Kim, Sung-Chul
    • Journal of the Korean Society of Safety
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    • v.37 no.4
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    • pp.20-27
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    • 2022
  • This article aims to develop an algorithm that detects fire pump defects by analyzing the current signals of an induction motor, which are triggered by changes in the flow rate and pressure of multistage volute pumps that are used for fire services. The operational status of the pumps was categorized into three: first, normal operation; second, a defect that is caused by a change in the current value; and third, a defect occasioned by a change in current, pressure, and flow rate. When a fire pump was in normal operation, the motor's operating current was measured between 5.06 A and 6.9 A, the flow rate was estimated at 0-0.27 m3/min, and the pressure ranged from 0 to 0.47 MPa. In the event that a defect was caused by an abnormal current value in the motor, it was attributed to the pump's adherence. Furthermore, if there was no source of water, the defect was considered to have been induced by phase-loss operation, no-load operation, or run-stop operation, with the current value of each scenario being measured at > 52.8 A, < 4.13 A, > 45.15 A, and < 3.8 A, respectively, placing its overall range between 0 and 50 A. The sources of defects were detected based on an analysis of the flow rate, pressure, and current, which represent the following causes: air inflow into the casing, inadequate suction of water, and reverse-phase operation, respectively. Each cause entailed the following values: when air seeped into the casing, the pressure was measured at 0.24 MPa irrespective of changes in the flow rate; when there was inadequate suction of water, the pressure was recorded between 0 and 0.05 MPa despite changes in the flow rate; and when the power line's reverse-phase loss was the cause of the defect, the pressure was measured at 0.33 MPa for a flow rate of 0 L/min, and a higher flow rate decreased the pressure to nearly 0 MPa. The results of this study will enable engineers to develop a pump defect detection algorithm that is based on an analysis of current, and this algorithm will facilitate the execution of a program that will control a fire pump defect detection system.

Secondary Science Teachers' Perception about and Actual Use of Visual Representations in the Teaching of Electromagnetism (중등 전자기 수업에서 사용하는 시각적 표상에 대한 교사 인식 및 활용 실태)

  • Yoon, Hye-Gyoung;Jo, Kwanghee;Jho, Hunkoog
    • Journal of The Korean Association For Science Education
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    • v.37 no.2
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    • pp.253-262
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    • 2017
  • This study aims at investigating the perceptions of science teachers about the role of visual representations in the teaching of electromagnetism, and finding out how science teachers use visual representations in their teaching of electromagnetism and the difficulties they experience in dealing with those representations. A total of 121 science teachers responded to the online survey. The results showed that most of the teachers agreed to the significance of using visual representations in the classroom but regarded their role as means of simply delivering science knowledge rather than constructing or generating knowledge. For the three visual representations widely used in teaching of electromagnetism in secondary schools (electrostatic induction on electroscope, magnetic field around current carrying wire, structure and principle of electric motor), the teachers preferred teacher-centered use of visual representations rather than student-centered and teacher's construction of representations were the most frequent among four types of use; interpretation, construction, application, and evaluation. The difficulties of teaching with these three visual representations were categorized into several factors; teachers, students, the characteristics of the representations, and lack of resources and classroom environment. Teachers' limited perceptions about the role of visual representations were associated with the ways of using visual representations in their teaching. Implications for the effective use of visual representations for science learning and teaching were discussed.

A Study for Predicting Rotational Cutting Torque from Electrical Energy Required for Ground Drilling (지반절삭 전기에너지를 활용한 회전굴착토크 예측에 관한 연구)

  • Choi, Chang-Ho;Cho, Jin-Woo;Lee, Yong-Soo;Chung, Ha-Ik;Park, Yong-Boo
    • Journal of the Korean Geotechnical Society
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    • v.23 no.7
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    • pp.57-64
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    • 2007
  • This study proposes a method to estimate drilling torque during ground boring with an aid of electrical energy required for rotating a boring-auger. Ground boring is commonly used in geotechnical engineering such as preboring precast pile installation, soil-cement grouting, ground exploration and so forth. In order to understand the correlation between required electrical energy to rotate the boring auger and the drilling torque, a small laboratory apparatus was designed and a pilot study was performed. The apparatus rotates common drill bits of $D=5{\sim}25mm$ in CBR specimens. The velocity of a bit is 19 RPM and predefined using a reduction gear which connects a main rotation axis to a 25 Watts AC electrical motor shaft. In the middle of drilling the motor current increments and the drilling torque were measured and the correlation between the current and the torque was obtained through linear square fits. Based on the correlation the acquired motor current during drilling was applied to predict the drilling torque in consequent testing and the prediction results were compared to the measured torque. The comparison leads a conclusion that the motor current during drilling using electrical power may be a good indicator to estimate/determine strength characteristics of the ground.