Magnetic Performance of (Nd,Ce)-Fe-B-type Die-upset Hybrid Magnet Composed of Melt-spun and HDDR-treated Materials

Dagus R. Djuanda,M. S. Kang,H. W. Kwon,D. H. Kim,J. G. Lee,H. J. Kim 한국자기학회 2019 Journal of Magnetics Vol.24 No.4

Ce-containing (Nd,Ce)-Fe-B-type hybrid magnet was fabricated by die-upset technique using two different types of materials: Ce-substituted (Nd0.55Ce0.45)15Fe72.2Co6.6Ga0.6B5.6 HDDR powder and melt-spun Nd13.6Fe73.6Co6.6Ga0.6B5.6 flakes. Magnetic performance of the hybrid magnet was superior to that of the single alloy magnet when they had identical overall composition: iHc = 6.8 kOe, Mr = 10.6 kG, and (BH)max = 19.8 MGOe for the Ce-containing hybrid magnet and iHc = 3.9 kOe, Mr = 9.8 kG, and (BH)max = 11.6 MGOe for the magnet from the single alloy HDDR powder. Die-upset hybrid magnet consisting of two constituent materials showed smooth and single-material-like demagnetization behavior, and this was attributed to the exchange interaction between neighbouring grains in the magnet.

Research on Tangential Magnetization Parallel Magnetic Path Hybrid Excitation Synchronous Machine

Pang Liang,Zhao ChaoHui,Shen HeBiao 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

A hybrid excitation motor with strong magnetizing ability is proposed. To solve the existing hybrid excitation machine problems, such as the diffi culty of total adjustment of air gap magnetic fi eld, many additional magnetic paths, fault tolerance is poor, and Air gap fl ux density harmonic distortion rate is high. According to the structural characteristics and the principle of magnetic regulation of tangential magnetization parallel magnetic path hybrid excitation synchronous machine. The equivalent magnetic path model of the motor was established, and the infl uence of electric excitation magnetic potential on permanent magnetic potential and air gap magnetic fi eld was analyzed. With the ANSYS Maxwell fi nite element simulation software, the variation law of the magnetic fi eld of the motor under diff erent excitation conditions is studied. The infl uence of pole boot length and magnetic pole eccentricity on air gap fl ux density amplitude and harmonic distortion rate is discussed. The results show that due to the characteristics of the parallel magnetic path. The motor has obvious eff ect of adjusting magnetic fi eld and gathering magnetic fi eld, motor fault tolerance is excellent, and less additional magnetic path. In addition, the air gap density can be optimized by using reasonable pole boot length and magnetic pole eccentricity.

Study of a Hybrid Magnet Array for an Electrodynamic Maglev Control

Chan Ham,Wonsuk Ko,Kuo-Chi Lin,Younghoon Joo 한국자기학회 2013 Journal of Magnetics Vol.18 No.3

This paper introduces an innovative hybrid array consisting of both permanent and electro magnets. It will enable us to develop an active control mechanism for underdamped electro-dynamic suspension (EDS) Maglev systems. The proposed scheme is based on the Halbach array configuration which takes the major technical advantage from the original Halbach characteristics: a strongly concentrated magnetic field on one side of the array and a cancelled field on the opposite side. In addition, the unique feature of the proposed concept only differs from the Halbach array with permanent magnets. The total magnetic field of the array can be actively controlled through the current of the electro-magnet’s coils. As a result, the magnetic force produced by the proposed hybrid array can also be controlled actively. This study focuses on the magnetic characteristics and capability of the proposed array as compared to the basic Halbach concept. The results show that the proposed array is capable of producing not only an equivalent suspension force of the basic Halbach permanent magnet array but also a controlled mode. Consequently, the effectiveness of the proposed array confirms that this study can be used as a technical framework to develop an active control mechanism for an EDS Maglev system.

Magnetization of a Modified Magnetic Quantum Dot

Park, Dae-Han,Kim, Nammee The Korean Vacuum Society 2016 Applied Science and Convergence Technology Vol.25 No.6

The energy dispersion and magnetization of a modified magnetic dot are investigated numerically. The effects of additional electrostatic potential, magnetic field non-uniformity, and Zeeman spin splitting are studied. The modified magnetic quantum dot is a magnetically formed quantum structure that has different magnetic fields inside and outside of the dot. The additional electrostatic potential prohibits the ground-state angular momentum transition in the energy dispersion as a function of the magnetic field inside the dot, and provides oscillation of the magnetization as a function of the chemical potential energy. The magnetic field non-uniformity broadens the shape of the magnetization. The Zeeman spin splitting produces additional peaks on the magnetization.

Magnetization of a Modified Magnetic Quantum Dot

박대한,김남미 한국진공학회 2016 Applied Science and Convergence Technology Vol.25 No.6

The energy dispersion and magnetization of a modified magnetic dot are investigated numerically. The effects of additional electrostatic potential, magnetic field non-uniformity, and Zeeman spin splitting are studied. The modified magnetic quantum dot is a magnetically formed quantum structure that has different magnetic fields inside and outside of the dot. The additional electrostatic potential prohibits the ground-state angular momentum transition in the energy dispersion as a function of the magnetic field inside the dot, and provides oscillation of the magnetization as a function of the chemical potential energy. The magnetic field non-uniformity broadens the shape of the magnetization. The Zeeman spin splitting produces additional peaks on the magnetization.

Magnetization of a Modified Magnetic Quantum Dot

Dae-Han Park,Nammee Kim 한국진공학회(ASCT) 2016 Applied Science and Convergence Technology Vol.25 No.6

The energy dispersion and magnetization of a modified magnetic dot are investigated numerically. The effects of additional electrostatic potential, magnetic field non-uniformity, and Zeeman spin splitting are studied. The modified magnetic quantum dot is a magnetically formed quantum structure that has different magnetic fields inside and outside of the dot. The additional electrostatic potential prohibits the ground-state angular momentum transition in the energy dispersion as a function of the magnetic field inside the dot, and provides oscillation of the magnetization as a function of the chemical potential energy. The magnetic field non-uniformity broadens the shape of the magnetization. The Zeeman spin splitting produces additional peaks on the magnetization.

플라이휠 에너지 저장장치를 위한 저 전력소모 하이브리드 마그네틱 베어링의 설계

김우연(Kim, Woo-Yeon),이종민(Lee, Jong-Min),배용채(Bae, Yong-Chae),김승종(Kim, Seung-Jong) 한국소음진동공학회 2010 한국소음진동공학회 논문집 Vol.20 No.8

For the application into a 1 kWh flywheel energy storage system(FESS), this paper presents the design scheme of radial and axial hybrid magnetic bearings which use bias fluxes generated by permanent magnets. In particular, the axial hybrid magnetic bearing is newly proposed in this paper, in which a permanent magnet is arranged in axial direction so that it can support the rotor weight as well as provide a bias flux for axial magnetic bearing. Such hybrid magnetic bearings consume very low power, compared with conventional electromagnetic bearings. In this paper, to stably support a 140 kg flywheel rotor without contact, design process is explained in detail, and magnetic circuit analysis and three-dimensional finite element analysis are carried out to determine the design parameters and predict the performance of the magnetic bearings.

Robust Zero Power Levitation Control of Quadruple Hybrid EMS System

Su-Yeon Cho,Won-Ho Kim,Ik-Sang Jang,Dong-Woo Kang,Ju Lee 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.6

This paper presents the improved zero power levitation control algorithm for a quadruple hybrid EMS (Electromagnetic Suspension) system. Quadruple hybrid EMS system is a united form of four hybrid EMS systems one on each corner coupled with a metal plate. Technical issue in controlling a quadruple hybrid EMS system is the permanent magnet’s equilibrium point deviation caused by design tolerance which eventually leads to a limited zero power levitation control that only satisfies the zero power levitation in one or two hybrid EMS system among the four hybrid EMS system. In order to satisfy a complete zero power levitation control of the quadruple hybrid EMS system, the proposed method presented in this paper adds a compensating algorithm which adjusts the gap reference of each individual axe. Later, this paper proves the stability and effectiveness of the proposed control algorithm via experiment and disturbance test.

Robust Zero Power Levitation Control of Quadruple Hybrid EMS System

Cho, Su-Yeon,Kim, Won-Ho,Jang, Ik-Sang,Kang, Dong-Woo,Lee, Ju The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.6

This paper presents the improved zero power levitation control algorithm for a quadruple hybrid EMS (Electromagnetic Suspension) system. Quadruple hybrid EMS system is a united form of four hybrid EMS systems one on each corner coupled with a metal plate. Technical issue in controlling a quadruple hybrid EMS system is the permanent magnet's equilibrium point deviation caused by design tolerance which eventually leads to a limited zero power levitation control that only satisfies the zero power levitation in one or two hybrid EMS system among the four hybrid EMS system. In order to satisfy a complete zero power levitation control of the quadruple hybrid EMS system, the proposed method presented in this paper adds a compensating algorithm which adjusts the gap reference of each individual axe. Later, this paper proves the stability and effectiveness of the proposed control algorithm via experiment and disturbance test.

Magnetic Resonance Imaging of the Inner Ear by Using a Hybrid Radiofrequency Coil at 7 T

김경남,허필,김영보,한규철 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.2

Visualization of the membranous structures of the inner ear has been limited to the detection ofthe normal fluid signal intensity within the bony labyrinth by using magnetic resonance imaging(MRI) equipped with a 1.5 Tesla (T) magnet. High-field (HF) MRI has been available for morethan a decade, and numerous studies have documented its significant advantages over conventionalMRI with regards to its use in basic scientific research and routine clinical assessments. No previousstudies of the inner ear by using HF MRI have been reported, in part because high-quality resolutionof mastoid pneumatization is challenging due to artifacts generated in the HF environment andinsufficient performance of radiofrequency (RF) coils. Therefore, a hybrid RF coil with integratedcircuitry was developed at 7 T and was targeted for anatomical imaging to achieve a high resolutionimage of the structure of the human inner ear, excluding the bony portion. The inner-ear’s structureis composed of soft tissues containing hydrogen ions and includes the membranous labyrinth,endolymphatic space, perilymphatic space, and cochlear-vestibular nerves. Visualization of theinner-ear’s anatomy was performed in-vivo with a custom-designed hybrid RF coil and a specificimaging protocol based on an interpolated breath-held examination sequence. The comparativesignal intensity value at 30-mm away from the phantom side was 88% higher for the hybrid RF coiland 24% higher for the 8-channel transmit/receive (Tx/Rx) coil than for the commercial birdcagecoil. The optimized MRI protocol employed a hybrid RF coil because it enabled high-resolutionimaging of the inner-ear’s anatomy and accurate mapping of structures including the cochlea andthe semicircular canals. These results indicate that 7 T MRI achieves high spatial resolution visualizationof the inner-ear’s anatomy. Therefore, MRI imaging using a hybrid RF coil at 7 T couldprovide a powerful tool for clinical investigations of petrous pathologies of the inner ear.