• Title/Summary/Keyword: magnetic flux sensor

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Implementation of a Senseless Position Controller Capable of Multi-turn Detection in a Turret Servo System (터렛 서보 시스템에서 멀티-턴 검출이 가능한 센서리스 위치제어기 구현)

  • Cho, Nae-Soo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.1
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    • pp.37-44
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    • 2021
  • This study is implemented as a sensor-less position controller capable of multi-turn detection to replace the expensive absolute encoder used in the turret servo system. For sensor-less control, the position information of the rotor is essential. For this, a magnetic flux estimator was implemented from the mathematical model of IPMSM used in the turret servo system. The position of the rotor and the angular velocity of the rotor were obtained using the rotor magnetic flux calculated from the magnetic flux estimator. Using the zero-crossing technique, one pulse was generated for each rotation of the estimated rotor magnetic flux to measure the number of multi-turns. Simulation and experiment results confirmed the usefulness of the proposed method.

Design of Magnet Console for NMR Ripeness Sensor Using ANSYS

  • Cho, Seong-In;Chung, Chang-Ho;Kim, Seung-Chan
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 1996.06c
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    • pp.528-538
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    • 1996
  • A magent console is critical element since its homogeneity is essential to the performance of a nuclear magnetic resonance (NMR) based sensor. Geometry and properties of magnet materials determine the magnetic flux density and homogeneity of the console. This study is carried out to develop a design scheme of the magnet console using ANSYS to reduce the design error of the magnet console compared . To enhance the performance of the magnet console, corner steel was proposed and validated by simulation and manufactured one. The corner steel increased the magnetic flux density (B) by about 1% and enhanced homogeneity by approximately 3 times. There was about 3% difference between simulated and measured B values.

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On-line Compensation Method for Magnetic Position Sensor using Recursive Least Square Method (재귀형 최소 자승법을 이용한 자기 위치 센서의 실시간 보상 방법)

  • Kim, Ji-Won;Moon, Seok-Hwan;Lee, Ji-Young;Chang, Jung-Hwan;Kim, Jang-Mok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.12
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    • pp.2246-2253
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    • 2011
  • This paper presents the error correction method of magnetic position sensor using recursive least square method (RLSM) with forgetting factor. Magnetic position sensor is proposed for linear position detection of the linear motor which has tooth shape stator, consists of permanent magnet, iron core and linear hall sensor, and generates sine and cosine waveforms according to the movement of the mover of the linear motor. From the output of magnetic position sensor, the position of the linear motor can be detected using arc-tan function. But the variation of the air gap between magnetic position sensor and the stator and the error in manufacturing process can cause the variation in offset, phase and amplitude of the generated waveforms when the linear motor moves. These variations in sine and cosine waveforms are changed according to the current linear motor position, and it is very difficult to compensate the errors using constant value. In this paper, the generated sine and cosine waveforms from the magnetic position sensor are compensated on-line using the RLSM with forgetting factor. And the speed observer is introduced to reduce the effect of uncompensated harmonic component. The approaches are verified by some simulations and experiments.

Time dependent numerical simulation of MFL coil sensor for metal damage detection

  • Azad, Ali;Lee, Jong-Jae;Kim, Namgyu
    • Smart Structures and Systems
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    • v.28 no.6
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    • pp.727-735
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    • 2021
  • Recently, non-destructive health monitoring methods such as magnetic flux leakage (MFL) method, have become popular due to their advantages over destructive methods. Currently, numerical study on this field has been limited to simplified studies by only obtaining MFL instead of induced voltage inside coil sensor. In this study, it was proposed to perform a novel numerical simulation of MFL's coil sensor by considering vital parameters including specimen's motion with constant velocity and saturation status of specimen in time domain. A steel-rod specimen with two stepwise cross-sectional changes (i.e., 21% and 16%) was fabricated using low carbon steel. In order to evaluate the results of numerical simulation, an experimental test was also conducted using a magnetic probe, with same size specimen and test parameters, exclusively. According to comparative results of numerical simulation and experimental test, similar signal amplitude and signal pattern were observed. Thus, proposed numerical simulation method can be used as a reliable source to check efficiency of sensor probe when different size specimens with different defects should be inspected.

Improvement of MFL sensing-based damage detection and quantification for steel bar NDE

  • Kim, Ju-Won;Park, Minsu;Kim, Junkyeong;Park, Seunghee
    • Smart Structures and Systems
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    • v.22 no.2
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    • pp.239-247
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    • 2018
  • A magnetic flux leakage (MFL) method was applied to detect and quantify defects in a steel bar. A multi-channel MFL sensor head was fabricated using Hall sensors and magnetization yokes with permanent magnets. The MFL sensor head scanned a damaged specimen with five levels of defects to measure the magnetic flux density. A series of signal processing procedures, including an enveloping process based on the Hilbert transform, was performed to clarify the flux leakage signal. The objective damage detection of the enveloped signals was then analyzed by comparing them to a threshold value. To quantitatively analyze the MFL signal according to the damage level, five kinds of damage indices based on the relationship between the enveloped MFL signal and the threshold value were applied. Using the proposed damage indices and the general damage index for the MFL method, the detected MFL signals were quantified and analyzed relative to the magnitude of the damage increase.

A Study on Determining the Shape of Small Axial Cracks by using Magnetic Flux Leakage in NDT System for Underground Pipe (배관용 자기누설 비파괴 검사에서 축방향 미소결함의 형상 판정에 관한 연구)

  • Kim, Hui Min;Park, Gwan Soo
    • Journal of the Korean Magnetics Society
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    • v.23 no.1
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    • pp.18-25
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    • 2013
  • MFL PIG (Magnetic Flux Leakage Pipeline Inspection Gauge) is called the system which detects the defect for underground pipelines by using magnetic flux leakage method in nondestructive testing. This method is very suitable for testing pipelines because pipeline has high magnetic permeability. MFL PIG generates the magnetic fields to the pipe axially oriented, and detect the signal of leakage flux by using hall sensor. However, MFL PIG is hard to detect the axially oriented crack with small size because the magnetic flux leakage is not enough to be occurred. To detect the small size and axially oriented crack, the circumferential MFL (CMFL) PIG is being proposed and it can maximize the leakage flux for the axial crack by performing magnetic fields circumferentially on the pipe. In this paper, CMFL PIG is applied to detect the axially oriented crack with small size and the analysis for the distribution and the amplitude of the leakage flux signal is performed by using three dimensional finite element method. From sensing signals, the method how to determine the shape of axially oriented cracks is proposed and verified with experiment.

Fabrication and Chracteristics of Magnetic Sensor using Ceramic Superconductor (산화물 초전도체를 이용한 자기센서의 제작 및 특성)

  • Lee, Sang-Heon
    • Journal of IKEEE
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    • v.3 no.2 s.5
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    • pp.243-249
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    • 1999
  • A magnetic field sensor is fabricated with superconducting ceramics of Y-Ba-Cu-O system. The prepared material shows the superconductivity at about 95K. The sensor at liquid nitrogen temperature shows the increase in electrical resistance by applying magnetic field. Actually, the voltage drop across the sensor is changed from zero to a value. more than $100{\mu}V$ by the applied magnetic field. The change in electrical resistance depends on magnetic field. The sensitivity of this sensor is 2.9 ohm/T. The sensing limit is about $1.5{\times}10^{-5}T(=1.5{\times}10^{-1}G)$. The increase in electrical resistance by the magnetic field is ascribed to a modification of the Josephson junctions due to the penetrating magnetic flux into the superconducting material.

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Field Oriented Vector Control of Induction Motor without Speed Sensor Using Flux Observer (자속관측기를 이용한 유도 전동기 자계 Orientation형 센서리스 벡터제어)

  • 손의식;홍순일
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.1
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    • pp.100-107
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    • 2003
  • This study was to control magnetic field orientation-typed sensorless vector control by applying the theory of a rotor flux observer to drive an induction motor. This research suggested a new speed estimation method that estimates speed with the rotor flux obtained by using a flux observer and the variable of state current detected by a current sensor without a speed sensor. Because the speed estimation method is independent from the motor constants, it is not necessary to control the gain of the parameters and the algorithm is simple. In the findings of the study, the researcher was convinced of the control function and the possibility of realization in the simulation experiment of sensorless vector control system by using DSP(Digital Signal Prosessor).

A Study on Air-gap Control for Transverse Flux Permanent Magnet Type Magnetic Levitation Electromagnet System (횡자속 영구자석형 자기부상전자석 시스템의 공극제어에 관한 연구)

  • Jae-Won Lee;Myeong-Jae Kim;Seon-Hwan Hwang
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.6_2
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    • pp.1127-1134
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    • 2023
  • In this paper, we proposes a study on air gap control for magnetic levitation of transverse flux permanent magnet electromagnets. In general, mechanical systems have a high failure rate of bearings. Bearings in particular are problematic because they have high surface wear rate and degradations. To solve this problem, replacing the bearing with a magnetic levitation electromagnet system can provide lightweight and efficiency improvements. However, precise air gap control is essential to control the magnetic levitation electromagnet system. Therefore, in this paper, we identify the instable cause of gap control through a mathematical modeling and verify through experiment a control algorithm that can use compensation.

Non-contact Electronic Joystick with a Hall Sensor for Effective Tele-operation (원격작업의 효율성 향상을 위한 단일 홀센서 비접촉식 전자 조이스틱)

  • Kim Hong-Chul;Kang Dae-Hoon;Lee Jang-Myung
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.4
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    • pp.358-363
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    • 2006
  • This paper demonstrates a new non-contact electronic joystick using single hall sensor which detects a horizontal vector of the magnetic field. Furthermore, in this paper, it is mathematically modeled that nonlinear characteristics between the output of hall sensor and the movement of joystick bar. The dynamic horizontal vector of magnetic flux is detected by the hall sensor while a permanent magnet is rotated with the joystick bar, which has two dimension detecting area. Using the nonlinear adjustment equations, the output signals of hall sensor have been linearized to give higher accuracy in the two dimension movement. Finally, through the real experiments, it is showed that the single hall sensor structure mechanism is superior to the dual sensor structure in sensing the two-dimensional motion without offset.