• Title/Summary/Keyword: magnetic measurement

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Design and Analysis of Lorentz Force-type Magnetic Bearing Based on High Precision and Low Power Consumption

  • Xu, Guofeng;Cai, Yuanwen;Ren, Yuan;Xin, Chaojun;Fan, Yahong;Hu, Dengliang
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.203-213
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    • 2017
  • Magnetically suspended control & sensitive gyroscope (MSCSG) is a novel type of gyroscope with the integration of attitude control and attitude angular measurement. To improve the precision and reduce the power consumption of Lorentz Force-type Magnetic Bearing (LFMB), the air gap flux density distribution of LFMB has been studied. The uniformity of air gap flux density is defined to qualify the uniform degree of the air gap flux density distribution. Considering the consumption, the average value of flux density is defined as well. Some optimal designs and analyses of LFMB are carried out by finite element simulation. The strength of the permanent magnet is taken into consideration during the machining process. To verify the design and simulation, a high-precision instrument is employed to measure the 3-dimensional magnetic flux density of LFMB. After measurement and calculation, the uniform degree of magnetic flux density distribution reaches 0.978 and the average value of the flux density is 0.482T. Experimental results show that the optimal design is effective and some useful advice can be obtained for further research.

Monitoring Inductance Change to Quantitatively Analyze Magnetic Wear Debris in Lubricating Oil (인덕턴스 측정에 의한 윤활유 내 자성입자 정량적 평가)

  • Koo, HeeJo;Ahn, Hyo-Sok
    • Tribology and Lubricants
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    • v.32 no.6
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    • pp.189-194
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    • 2016
  • Wear debris in lubricating oil can be indicative of potential damage to mechanical parts in rotating and reciprocating machinery. Therefore, on-line or in-line monitoring of lubricating components in machinery is of great importance. This work presents a device based on inductive measurement of lubricating oil to detect magnetic wear particles in a tested volume. The circuit in the device consists of Maxwell Bridge and LVDT to measure inductance differences between pure and contaminated oil. The device detects the passage of ferrous particles by monitoring inductance change in a coil. The sensing principle is initially demonstrated at the microscale using a solenoid. The device is then tested using iron particles ranging from $50{\mu}m$ to $100{\mu}m$, which are often found in severely worn mechanical components. The test results show that the device is capable of detecting and distinguishing ferrous particles in lubricating oil. The design concept demonstrated here can be extended to an in-line monitoring device for real-time monitoring of ferrous debris particles. A simulation using the CST code is performed to better understand the inductive response in the presence of magnetic bodies in the oil. The CST simulation further verifies the effectiveness of inductance measurement for monitoring magnetic particles within a tube.

Bias Estimation of Magnetic Field Measurement by AHRS Using UKF (UKF를 사용한 AHRS의 자기장 측정 편차 추정)

  • Ko, Nak Yong;Song, Gyeongsub;Jeong, Seokki;Lee, Jong-Moo;Choi, Hyun-Taek;Moon, Yong Seon
    • Journal of Ocean Engineering and Technology
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    • v.31 no.2
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    • pp.177-182
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    • 2017
  • This paper describes an unscented Kalman filter approach to estimate the bias in magnetic field measurements. A microelectromechanical systems attitude heading reference system (MEMS AHRS) was used to measure the magnetic field, together with the acceleration and angular rate. A magnetic field is usually used for yaw detection, while the acceleration serves to detect the roll and pitch. Magnetic field measurements are vulnerable to distortion due to hard-iron effect and soft-iron effect. The bias in the measurement accounts for the hard-iron effect, and this paper focuses on an approach to estimate this bias. The proposed method is compared with other methods through experiments that implement the navigation of an underwater robot using an AHRS and Doppler velocity log. The results verify that the compensation of the bias by the proposed method improves the navigation performance more than or comparable to the compensation by other methods.

Neutron Irradiation Effect of YBa2Cu3O7-y Superconductor (YBa2Cu3O7-y 초전도 벌크의 중성자 조사 효과)

  • Lee, Sang Heon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.34 no.6
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    • pp.438-441
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    • 2021
  • The electrical characteristics of single-crystal composite superconductors produced by a melting process were studied by neutron irradiation. In order to improve the current characteristics of the YBa2Cu3O7-y superconductor, it is necessary to form an effective flux pinning center inside the superconductor. In this study, an increase in flux pinning was attempted through neutron irradiation onto YBa2Cu3O7-y superconductors. The neutron irradiation was performed at 30 MeV for 500 sec, The electrical properties of the superconductors were measured in a magnetic field of 5 Tesla at 50 K using a magnetic properties measurement system (MPMS). After neutron irradiation, the critical current density of the YBa2Cu3O7-y superconductor in a 1 Tesla magnetic field was 1×105 A/cm2. Once neutrons were irradiated at 30 MeV and 10 μA for 500 sec, the critical current density was observed to increase significantly. When neutrons are irradiated to a superconductor, micro-defects are created in the superconductor, and they act as flux pinning centers that hold the magnetic field generated when an electric current flows.

The Measurement of Electromagnetic Wave in Power Cable Tunnel of Underground Utility Tunnel (전력구 내 전자기파에 대한 작업 환경 측정)

  • Kang, Dae Kon;Park, Jai Hak
    • Journal of the Korean Society of Safety
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    • v.34 no.1
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    • pp.1-7
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    • 2019
  • Electromagnetic measurements of the power cable tunnel were conducted from August 10 to 20, 2018, in the ${\bigcirc}{\bigcirc}$ city underground utility tunnel. During this period, the average temperature was $31.89^{\circ}C$ and the humidity was 67.56% in power cable tunnel. As a result of the electromagnetic measurement, the highest electric field was 25.3 V/m and the magnetic flux density was $42.6{\mu}T$. The average electric field was 18.56 V/m and the magnetic flux density was $29.32{\mu}T$ in the power cable tunnel. As a result of comparison with the electric equipment technical standard, the electric field in the power cable tunnel was 0.5% of the electric equipment standard and 35.2% of the magnetic flux density. It's similar value that electric field is about robotic vacuum(15.53 V/m), and magnetic flux density is similar value about capsule- type coffee machine ($23.07{\mu}T$). The number of cable lines and the size of the electromagnetic waves were not proportional to each other through comparison of cable lines in the power cable tunnel. It was confirmed that 154 kV, rather than 22.9 kV, could have a greater influence on occupational.

Evaluation Methods of Homogeneity for Feedstocks and Effect of Homogeneity on the Magnetic Properties of Plastic Magnets (플라스틱 자석 혼합물의 균질도 평가방법과 균질도가 자기특성에 미치는 영향)

  • 이석희;최준환;문탁진;정원용
    • Journal of the Korean Magnetics Society
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    • v.8 no.2
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    • pp.86-92
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    • 1998
  • Homegeneous feedstock is necessary to make plastic magents with uniform magnetic properties, therefore the optrimized mixing route and the homogeneity evaluation method are demanded. In this paper, method of homogeneity evaluation and effect of homogeneity on the magnetic prperites were investigated using Sr-ferrite /EVA plastic magnets. The feedstocks with different homogeneity were prepared using batch mixer and single screw extruder. The homogeneities of feedstocks were tested by torgue sensor, capilary rheometer, and measurement of magnetic properties. Mixing torque measurement using torque sensor was an effective method to determine the critical powder loading, but it was nor suitable to suitable to determine the feedstock mixing quality. Particle alignment measurement of a plastic magent was very accurate to evaluate the homogeneity, but expensive equipments were required to make and measure the samples. Pressure measurement using capillary rheometer was a very effective and easy method with high accuracy. Homogeneous feedstock increased the particle alignment of plastic magnet. Remanet flux density and maximum energy product increased linearly and quadratically with increasing particle alignment, respectively.

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Measurement of the Ship`s Magnetic Field in M . S . ARA by Use of Three Axis Magnetic Detect Elements (3축 자기검출소자를 이용한 아라호의 선내자계의 측정)

  • 안영화
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.31 no.4
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    • pp.385-392
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    • 1995
  • The authors have been studying about and electro-magnetic compass with a three axis magnetic sensor in order to provide and accurate ship's magnetic heading which the compass deviations can automatically compensated in the compass itself, and the theory how to derive the poisson's coefficients from ship's magnetism measured with three axis magnetic sensor. This paper describes on the analysis of deviation derived from the measured values that obtained to measure the various magnetic fields at the compass position of the M. S. ARA, training ship of Cheju University with three axis magnetic sensor at Cheju near sea from 25th, Oct, to 13th, Nov. in 1994.

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Magnetic Pole Structure of Electro-Magnet for Forming Uniform Magnetic Field (평등자계 형성용 전자석 자극 구조에 관한 연구)

  • 김정태;이승면;조현준;김훈년
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.515-518
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    • 2002
  • In this study, the ellipsoidal cap type magnetic pole structure was proposed for the electro-magnet in B-H curve tracer. From the simulation for the electro-magnet without specimen, the area of effective uniform field(99% range for the central field value) was considerably increased in case of the newly proposed ellipsoidal cap type magnetic pole than that of the conventional simple-inclined cap type magnetic pole. Also, through the simulation for the electro-magnet with permanent magnet specimen(NaFe30), the optimal Positions of the magnetic field measurement sensor(Hall sensor) were found out in each case and the errors were decreased in case of the newly proposed ellipsoidal cap type magnetic pole.

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Analysis and Comparision of Measured and Calculated Value on Magnetic Fields Strength under Transmission Lines (초고압 송전선로의 자계크기 해석과 실측 비교)

  • Cho, Sung-Bae;Lee, Eun-Woong
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.7
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    • pp.832-838
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    • 1999
  • Recently, there are growing concerns about power frequency electric and magnetic fields coming out from the high voltage transmission lines, because of the wide spread perception of their probable harmful effect on human body. In connection with this trend, this paper describes the electric and magnetic fields measurement result around 154 kV and 345 kV transmission lines, a comparison of measured EMF to calculated one and the correlations between transmission lines currents and measured magnetic fields. Daily maximum and minimum magnetic field quantities under the selected 154 kV and 345 kV transmission lines had been measured for 1 year of 1997 and the average value of magnetic field exposure under the lines were calculated and presented based on the measured data.

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The Effect of Cr doping on the Magnetic and Magnetocaloric Properties of MnCoGe Alloys

  • Emre, S. Yuce
    • Journal of Magnetics
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    • v.18 no.4
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    • pp.405-411
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    • 2013
  • The structural, magnetic and magnetocaloric properties of $CoMn_{1-x}Cr_xGe$ (x=0.05-0.125) have been investigated by using electron microscopy, x-ray diffraction, calorimetric and magnetic measurements. In this study, our aim is to justify the magnetocaloric effect by tuning the structural and magnetic transition temperature with Cr doping on CoMnGe pure system. The substitution of Cr for Mn leads to a decrease of both structural and magnetic transition temperatures. However, structural and magnetic transition temperatures do not close to each other. From magnetization measurement, we calculate that isothermal entropy change associated with magnetic transition can be as high as 3.82 J $kg^{-1}K^{-1}$ at 302 K in a field of 7 T. Meanwhile, structural phase transition contribution to isothermal entropy change is calculated as 5.85 J $kg^{-1}K^{-1}$ at 322 K for 7 T.