An investigation on the improved magnetic stiffness model and characteristic analysis for two cylindrical permanent magnets

This paper presents torque characteristic analysis of synchronous induction motors called “IM/PM hybrid motors” by using the two-dimensional finite element method taking terminal voltage into account. The slip characteristics are analyzed by using multi-meshes corresponding to each rotor position, because the transient numerical analysis is quite difficult due to slip even two-dimensional analysis. There are many researches on IM/PM hybrid motors, however the torque characteristics when they are operating as an induction motor have not yet examined sufficiently. In this paper, we tried to explore how to improve the torque characteristics even operating as an induction motor by incorporating the embedded permanent magnets. The results show that the arrangement of the permanent magnets is very important to improve whole torque characteristics.

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Mathematical Modeling and Characteristic Analysis of the Vertical Stiffness for Railway Vehicle Air Spring System

Mathematical Problems in Engineering ◽

10.1155/2020/2036563 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Liufeng Xu

Keyword(s):

Experimental Tests ◽

Geometric Parameters ◽

Railway Vehicle ◽

Characteristic Analysis ◽

Air Spring ◽

Vertical Stiffness ◽

Stiffness Model ◽

Spring System ◽

Stiffness Characteristics ◽

The Impact

Establishing a correct and reliable vertical stiffness model has an important significance on reproducing the characteristics of an air spring system. In this paper, a dynamic vertical stiffness model is developed based on thermodynamics and fluid dynamics, and geometric parameters are identified by an approximate analytical method. Meanwhile, experimental tests are performed to verify the accuracy and reliability of the proposed model. Furthermore, the impact of geometric parameters on the vertical stiffness characteristics is discussed through a sensitivity analysis. The conclusions show that the dynamic vertical stiffness model can well characterize the dynamic characteristics of the air spring system, which provides a theoretical basis for the optimal design of air spring parameters and the study of mechanical properties.

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Characteristic Analysis of Vernier Motor with Permanent Magnets in Stator Core

Journal of the Japan Society of Applied Electromagnetics and Mechanics ◽

10.14243/jsaem.29.346 ◽

2021 ◽

Vol 29 (2) ◽

pp. 346-351

Author(s):

Kenji OKADA ◽

Noboru NIGUCHI ◽

Katsuhiro HIRATA

Keyword(s):

Permanent Magnets ◽

Characteristic Analysis ◽

Stator Core

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Design and Analysis of a Magnetic QZS Vibration Isolator

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.470.484 ◽

2013 ◽

Vol 470 ◽

pp. 484-488 ◽

Cited By ~ 2

Author(s):

Hui Li ◽

Jing Zhang

Keyword(s):

Dynamic Analysis ◽

Permanent Magnet ◽

Permanent Magnets ◽

Approximate Expression ◽

Repulsive Force ◽

Vibration Isolator ◽

Coil Spring ◽

Characteristic Analysis ◽

Unique Relationship

In this paper, a novel nonlinear magnetic vibration isolator is developed. The developed isolators possess the characteristic of quasi-zero stiffness (QZS). It is obtained by connecting a vertical coil spring with two permanent magnet springs in couple with three permanent magnets. Firstly, the permanent magnet spring is introduced, and approximate expression of repulsive force in the permanent magnet spring is proposed. Secondly, characteristic analysis of system is investigated. It is shown that there is a unique relationship between the stiffness of vertical spring and parameters of system that yields a QZS system. The approximate stiffness of QZS system can be used instead of the analytical stiffness in dynamic analysis.

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EM of rapidly solidified permanent magnets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121399 ◽

1992 ◽

Vol 50 (1) ◽

pp. 198-199

Author(s):

Raja K. Mishra

Keyword(s):

Melt Spinning ◽

Permanent Magnets ◽

Dark Field Image ◽

Dark Field ◽

Maximum Energy ◽

Quench Rate ◽

Maximum Energy Product ◽

Energy Product ◽

Annular Dark Field ◽

Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

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Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178082 ◽

1990 ◽

Vol 48 (4) ◽

pp. 990-991

Author(s):

Mahesh Chandramouli

Keyword(s):

Electron Microscope ◽

Liquid Phase ◽

Permanent Magnets ◽

Phase Distribution ◽

Energy Dispersive Spectrometer ◽

Nucleation And Growth ◽

Liquid Phase Sintering ◽

Domain Wall Energy ◽

Oxide Phases ◽

Scanning Electron

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.

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Characterisation of planar crystal defects in Y2Fe17Cx (0.6 ≤ x ≤ 1.6) magnetic material by High Resolution Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177003 ◽

1990 ◽

Vol 48 (4) ◽

pp. 774-775

Author(s):

W. Coene ◽

F. Hakkens ◽

T.H. Jacobs ◽

K.H.J. Buschow

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Permanent Magnets ◽

Annealing Treatment ◽

High Resolution Electron Microscopy ◽

Crystal Defects ◽

Ordered Structure ◽

X Ray ◽

Planar Crystal ◽

Resolution Electron

Intermetallic compounds of the type RE2Fe17Cx (RE= rare earth element) are promising candidates for permanent magnets. In case of Y2Fe17Cx, the Curie temperature increases from 325 K for x =0 to 550 K for x = 1.6 . X ray and electron diffraction reveal a carbon - induced structural transformation in Y2Fe17Cx from the hexagonal Th2Ni17 - type (x < 0.6 ) to the rhombohedral Th2Zn17 - type ( x ≥ 0.6). Planar crystal defects introduce local sheets of different magnetic anisotropy as compared with the ordered structure, and therefore may have an important impact on the coercivivity mechanism .High resolution electron microscopy ( HREM ) on a Philips CM30 / Super Twin has been used to characterize planar crystal defects in rhombohedral Y2Fe17Cx ( x ≥ 0.6 ). The basal plane stacking sequences are imaged in the [100] - orientation, showing an ABC or ACB sequence of Y - atoms and Fe2 - dumbbells, for both coaxial twin variants, respectively . Compounds resulting from a 3 - week annealing treatment at high temperature ( Ta = 1000 - 1100°C ) contain a high density of planar defects.

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