Design of quasi-axisymmetric stellarators with varying-thickness perpendicular permanent magnets based on “two-step” magnet design strategy

A permanent magnet Brushless DC (BLDC) motor has been designed with different rotor configurations based on the arrangement of the permanent magnets. Rotor configurations strongly affect the torque and efficiency performance of permanent magnet electric motors. In this paper, different rotor configurations of the permanent magnet BLDC motor with parallel the Halbach array permanent magnet were compared and evaluated. Many applications of electric drives or air-crafts have recently preferred the surface-mounted permanent magnet design due to its ease of construction and maintenance. The finite element technique has been used for the analysis and comparison of different geometry parameters and rotor magnet configurations to improve efficiency and torque performance. A comprehensive design of a three-phase permanent magnet BLDC 35kW motor is presented and simulations were conducted to evaluate its design. The skewing rotor and Halbach magnet array are applied to the permanent surface-mounted magnet on the BLDC motor for eliminating torque ripples. In order to observe the skewing rotor effect, the rotor lamination layers were skewed with different angles and Halbach sinusoidal arrays. The determined skewing angle, the eliminated theoretically cogging torque, and the back electromotive force harmonics were also analyzed.

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Design of quasi-axisymmetric stellarators with varying-thickness permanent magnets based on Fourier and surface magnetic charges method

Nuclear Fusion ◽

10.1088/1741-4326/abcdb6 ◽

2020 ◽

Author(s):

Guo Sheng Xu ◽

Zhiyuan Lu ◽

Dehong Chen ◽

Liang Chen ◽

Xiangyu Zhang ◽

...

Keyword(s):

Permanent Magnets ◽

Varying Thickness

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Optimal sizing design of a 1.5 MW permanent magnets synchronous generator for an onshore wind conversion system

Renewable Energy and Power Quality Journal ◽

10.24084/repqj19.368 ◽

2021 ◽

Vol 19 ◽

pp. 630-635

Author(s):

H. Gallas ◽

◽

S. Le Ballois ◽

H. Aloui ◽

L. Vido

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Permanent Magnets ◽

Synchronous Generator ◽

Element Model ◽

Design Strategy ◽

Design Parameters ◽

Mapping Technique ◽

Good Efficiency ◽

Optimal Sizing

This paper proposes a fast and accurate optimal sizing design of 1.5 MW Permanent Magnets Synchronous Generator (PMSG) for a grid-connected wind application. A design strategy inspired from the output space mapping technique is adopted. A fast analytical model is used and detailed to determine the parameters and the performances of the PMSG. Then, the results are validated by a precise finite element model and adjusted iteratively until coherence between the two models is obtained. A multi-objective particle swarm optimization algorithm is deployed with aim of reducing the total losses and weight of the generator. The algorithm's parameters and results are given and analyzed. Three optimal machines are chosen and tested using a 2D-finite element model. The main design parameters of the optimal generators are given and discussed. Good efficiency and optimal designs are obtained for the sized machines thanks to the adopted design strategy.

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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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