• Title, Summary, Keyword: magnetization

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Study on the Post-Assembly Magnetization Method of Permanent Magnet Motor (영구자석형 전동기의 조립 후 착자 방법에 대한 연구)

  • Lee, C.K.;Kwon, B.I.
    • Proceedings of the KIEE Conference
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    • pp.104-106
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    • 2003
  • In this paper, we study about the stator winding magnetization method and the magnetizing fixture magnetization method in post-assembly magnetization. Most of small electrical machine use the stator winding magnetization method but it is impossible to magnetize the permanent magnet by the stator winding magnetization method when the capacity of machine increases and the coercive force of magnet increases. And the eddy current disturbs the magnetization seriously in case of LSPM(Line Start Permanent magnet Motor) that have conductor bar in rotor. Hence, the magnetization fixture is required. So, in this paper we study about the post-assembly magnetization method that can use the stator winding magnetization method or must use the magnetization fixture magnetization method.

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Precision Determination of Anisotropy Constant $K_1$from Magnetization Curve of Partially Aligned Unaxial Anisotropy System

  • Kim, Yoon-Bae;Kim, Hyoung-Tae
    • Journal of Magnetics
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    • v.6 no.4
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    • pp.142-144
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    • 2001
  • A method to deduce the rotational magnetization curve from experimental magnetization of partially aligned uniaxial anisotropy system has been investigated. The curve obtained by this process has been evaluated quire close to the theoretical magnetization curve compared to that obtained by linear extrapolation from high field data. This new approach offers better accuracy for the determination of magnetic anisotropy by fitting a calculated magnetization curve to the obversed one.

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Identification of Unknown Remanent Magnetization in the Ferromagnetic Ship Hull Utilizing Material Sensitivity Information Combined with Magnetization Modeling

  • Kim, Nam-Kyung;Jeung, Gi-Woo;Yang, Chang-Seob;Chung, Hyun-Ju;Kim, Dong-Hun
    • Journal of Magnetics
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    • v.16 no.2
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    • pp.114-119
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    • 2011
  • This paper presents a magnetization modeling method combined with material sensitivity information to identify the unknown magnetization distribution of a hull and improve the accuracy of the predicted fields. First, based on the magnetization modeling, the hull surface was divided into three-dimensional sheet elements, where the individual remanent magnetization was assumed to be constant. For a fast search of the optimum magnetization distribution on the hull, a material sensitivity formula containing the first-order gradient information of an objective function was combined with the magnetization modeling method. The feature of the proposed method is that it can provide a stable and accurate field solution, even in the vicinity of the hull. Finally, the validity of the method was tested using a scale model ship.

Magnetization Fault Diagnosis of Concentrated Winding BLDC Motors for Compressor (압축기용 집중권 BLDC 전동기의 착자 불량 진단)

  • Lee, Kwang-Woon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.14 no.3
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    • pp.197-203
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    • 2009
  • This paper presents a novel method to diagnose magnetization faults produced during magnetization process using stator coils of a brushless dc motor with concentrated windings. It is demonstrated that the stator coil magnetization faults can cause a drop of energy efficiency of the brushless dc motor through computer simulations using a magnetization fault model and efficiency test using compressors. The proposed method diagnoses the stator coil magnetization faults by using an inverter during the brushless dc motor driving test after the magnetization process is completed. An experimental study on the brushless dc motor for compressor shows that the stator coil magnetization faults can be detected with high sensitivity.

A Study on Intial Susceptibility for the Prediction of Vertical Magnetization in Flash D Demagnetization (Flash D 탈자방법에서 수직자화예측을 위한 초기자화율에 관한 검토)

  • Kim, Young-Hak;Doh, Jaewon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.5
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    • pp.585-590
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    • 2014
  • A permanent vertical magnetization should be obtained to counteract induced vertical magnetization due to the earth's background field during the Flash D demagnetization process. A vertical susceptibility is needed to calculate a extra-permanent magnetization, which is needed to control the permanent vertical magnetization in stage 2 of Flash D demagnetization and added to the final vertical permanent magnetization. Two susceptibilities were found in this paper. One is obtained from the extra-magnetization. The other is obtained by magnetic field measurement from the scaled physical vessel when the vessel is excited by vertical magnetic field. The initial susceptibility by the extra-magnetization was 0.101~0.109 and the one from the measured magnetic field was 0.122. Two susceptibilities have a good agreement each other. From this paper, it is found that the susceptibility is able to appllied to calculate the extr-magnetization.

Measurement of the Magnetization Loss in a HTS Tape (고온초전도선재의 자화손실 측정)

  • Sim, Jeong-Uk;Lee, Hui-Jun;Cha, Gwi-Su;Lee, Ji-Gwang;Han, Song-Yeop
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.48 no.4
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    • pp.182-186
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    • 1999
  • Evaluation of the AC losses in the HTS tapes which are used in electric power machines in one of the important topics in this field. This paper deals with the calculation and measurement of the magnetization loss in HTS tapes. Bean model is adopted for the theoretical calculation of the magnetization loss. Magnetization method is used for the measurement of the loss. Two types of the HTS tape model, multi-filamentary model and mono-filamentary model, are used to evaluate the magnetization loss in this paper. According to the results of the analysis, large discrepancy between the calculated and measured value is observed in multi-filamentary model is more useful than multi-filamentary model for the evaluation of the magnetization loss.

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Magnetization Behavior of CoB/Ru/CoB Thin Film (CoB/Ru/CoB 박막 재료의 자화 거동 특성 분석)

  • Kim, Dong Young;Yoon, Seok Soo
    • Journal of the Korean Magnetics Society
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    • v.23 no.5
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    • pp.154-158
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    • 2013
  • We have analyzed the magnetization curves measures by using VSM and MOKE in synthetic antiferromagnetic coupled CoB/Ru/CoB thin film. The measured results were compared with calculated ones by Stoner-Wohlfarth model based on the magnetization behavior of two ferromagnetic layers ($M_1$, $M_2$). The calculated total magnetization ($M_{tot}=M_1+M_2$) and single layer magnetization($M_1$) behaviors were compared with measured results by using VSM and MOKE, respectively. The total magnetization curve ($M_{tot}=M_1+M_2$) showed reversible magnetization behavior with flopping field of about 50 Oe. While single layer magnetization ($M_1$) behaviors showed irreversible magnetization behavior in the field range of $H_F$ < H < $H_F$. These magnetization behaviors were explained by the angle difference between magnetization directions of two ferromagnetic layers in SAF sample.

Computer Simulation of Switching Characteristics and Magnetization Flop in Magnetic Tunnel Junctions Exchange Biased by Synthetic Antiferromagnets

  • Lim, S.H.;Uhm, Y.R.
    • Journal of Magnetics
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    • v.6 no.4
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    • pp.132-141
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    • 2001
  • The switching characteristics and the magnetization-flop behavior in magnetic tunnel junctions exchange biased by synthetic antiferromagnets (SyAFs) are investigated by using a computer simulations based on a single-domain multilayer model. The bias field acting on the free layer is found to be sensitive to the thickness of neighboring layers, and the thickness dependence of the bias field is greater at smaller cell dimensions due to larger magnetostatic interactions. The resistance to magnetization flop increases with decreasing cell size due to increased shape anisotropy. When the cell dimensions are small and the synthetic antiferromagnet is weakly, or not pinned, the magnetization directions of the two layers sandwiching the insulating layer are aligned antiparallel due to a strong magnetostatic interaction, resulting in an abnormal magneto resistance (MR) change from the high-MR state to zero, irrespective of the direction of the free-layer switching. The threshold field for magnetization-flop is found to increase linearly with increasing antiferromagnetic exchange coupling in the synthetic antiferromagnet. Irrespective of the magnetic parameters and cell sizes, magnetization flop does not exist near zero applied field, indicating that magnetization flop is driven by the Zeeman energy.

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Influence Factor on Magnetization Property of Carbonyl Iron-based Magnetorheological Fluids

  • Wang, Daoming;Zi, Bin;Qian, Sen;Qian, Jun;Zeng, Yishan
    • Journal of Magnetics
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    • v.21 no.4
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    • pp.622-628
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    • 2016
  • Magnetization property is a critical factor for magnetorheological fluids (MRFs) to achieve the liquid-solid transition. The main focus of this study is on exploring the influence factors on magnetization properties of MRFs. In this paper, a theoretical analysis is performed to discuss the magnetization characteristics of MRFs firstly. Then, a method for the preparation of carbonyl iron-based MRFs is illustrated and five MRFs samples with various material parameters are prepared. It is succeeded by a series of experiments on testing the hysteresis loop and the magnetization curve of each sample and the influence factors are compared and analyzed. Experimental results indicate that there is basically no hysteresis phenomenon on MRFs which exhibits superparamagnetic behavior at room temperature. A surfactant coating on magnetic particles can slightly improve the MRFs magnetization. Additionally, the magnetic susceptibility and the saturation magnetization both increase with the particle concentration, whereas the influence of particle diameter is relatively very small. Moreover, as the temperature increases, the magnetization decreases and the declining rate accelerates gradually.

Comparison of Three Modeling Methods for Identifying Unknown Magnetization of Ferromagnetic Thin Plate

  • Choi, Nak-Sun;Kim, Dong-Wook;Yang, Chang-Seob;Chung, Hyun-Ju;Kim, Hong-Joon;Kim, Dong-Hun
    • Journal of Electrical Engineering and Technology
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    • v.6 no.6
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    • pp.799-805
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    • 2011
  • This study presents three different magnetization models for identifying unknown magnetization of the ferromagnetic thin plate of a ship. First, the forward problem should be solved to accurately predict outboard magnetic fields due to the magnetization distribution estimated at a certain time. To achieve this, three different modeling methods for representing remanent magnetization (i.e., magnetic charge method, magnetic dipole array method, and magnetic moment method) were utilized. Material sensitivity formulas containing the first-order gradient information of an objective function were then adopted for an efficient search of an optimum magnetization distribution on the hull. The validity of the proposed methods was tested with a scale model ship, and field signals predicted from the three different models were thoroughly investigated with reference to the experimental data.