scholarly journals The Study of Demagnetization of the Magnetic Orientation of Permanent Magnets for IPMSM with Field-Weakening Control under Hot Temperature

2018 ◽  
Vol 6 (3) ◽  
Author(s):  
Noriyoshi Nishiyama ◽  
Hiroki Uemura ◽  
Yukio Honda
Keyword(s):  
Permanent Magnets ◽  
Magnetic Orientation ◽  
Field Weakening ◽  
Hot Temperature

scholarly journals Detection of Partial Demagnetization Faults in Five-Phase Permanent Magnet Assisted Synchronous Reluctance Machines

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3496
Author(s):  
Carlos Candelo-Zuluaga ◽  
Jordi-Roger Riba ◽  
Dinesh V. Thangamuthu ◽  
Antoni Garcia
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Short Circuit ◽  
Detection Methods ◽  
Element Analysis ◽  
Field Weakening ◽  
Synchronous Reluctance Motor ◽  
Harmonic Content ◽  
Zero Sequence ◽  
Demagnetization Faults

This paper analyzes partial demagnetization faults in a five-phase permanent magnet assisted synchronous reluctance motor (fPMa-SynRM) incorporating ferrite permanent magnets (PMs). These faults are relevant because of the application of field weakening, or due to high operating temperatures or short circuit currents, the PMs can become irreversibly demagnetized, thus affecting the performance and safe operation of the machine. This paper proposes fault indicators to detect such fault modes with low demagnetization levels between 5.0% to 16.7% relative demagnetization. Four partial demagnetization fault detection methods are tested, which are based on the analysis of the harmonic content of the electromotive force (EMF) under no load conditions, the harmonic content of the line currents, the harmonic content of the zero-sequence voltage component (ZSVC) and the analysis of the power factor (PF). This work also compares the sensitivity and performance of the proposed detection methods. According to the fault indicators proposed in this paper, the results show that the analysis of the EMF, ZSVC and PF are the most sensitive detection methods. Experimental results are presented to validate finite element analysis (FEA) simulations.

Performance Comparison of AFDS PMSG during Voltage Regulation by mechanical field-weakening in Extended-Speed-Range

2019 ◽  
Vol 13 ◽  
Author(s):  
Shailendra Kumar Gupta ◽  
Rakesh Kumar Srivastava
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Voltage Regulation ◽  
Performance Comparison ◽  
High Coercivity ◽  
Axial Flux ◽  
Field Weakening ◽  
Mechanical Field ◽  
Mechanical Methods ◽  
Speed Range

: Axial-flux permanent magnet generators have been found suitable in wind energy conversion system and electrical vehicle owing to its compactness, high torque to inertia ratio, modular geometry, and high magnet usability index. Such applications require the generator to operate in extended speed range. In extended speed range, voltage regulation of the generator is achieved by field-weakening of the generator. Usually, field-weakening is achieved by injecting negative d-axis current in the armature winding of the generator. However, in the axial-flux machine field-weakening by current injection is not substantial due to the low inductance of the machine and use of permanent magnets with high coercivity. Therefore, this paper emphasizes field-weakening using mechanical methods. This paper compares the performance of different axial-flux dual-stator permanent magnet generator (AFDS PMG) topologies on the basis of voltage regulation by mechanical-field-weakening-technique. Field-weakening in the generator is achieved by angularly displacing one of the stators with respect to other via a mechanical actuator. Experimental test results on proof-of-concept generators have been presented to conclude that AFDS PMSG with perfect sinusoidal back-emf characteristic is best suited for mechanical field-weakening-based voltage regulation in ESR.

scholarly journals DEVELOPMENT OF AN ALGORITHM FOR SWITCHING CONTROL STRATEGIES OF SALIENT SYNCHRONOUS MOTORS WITH PERMANENT MAGNETS

2021 ◽  
Vol 2021 (58) ◽  
pp. 30-38
Author(s):  
O.I. Tolochko ◽  
◽  
O.O. Burmelov ◽  
Ya.O. Kalenchuk ◽  
◽  
...  
Keyword(s):  
Permanent Magnets ◽  
Control Strategies ◽  
Permanent Magnet Synchronous Motor ◽  
Optimal Strategies ◽  
Motor Speed ◽  
Maximum Torque ◽  
Control Zone ◽  
Field Weakening ◽  
Wide Range ◽  
Maximum Torque Per Ampere

In this paper, a detailed analysis of the control algorithms for a permanent magnet synchronous motor in a wide range of speeds is carried out using the optimal strategies: "Maximum torque per ampere" (first zone), "Field weakening mode" (second zone) and "Maximum torque per volt" (third zone). A method for determining the boundaries of the first and second zones, as well as a method for determining the maximum static moment with which the motor can operate without the risk of irreversible demagnetization of permanent magnets, was proposed. It allows determining the maximum possible operating speed of the motor at a given load, the maximum motor load at a given speed, as well as the advisability of using the third control zone to achieve the maximum motor speed. References 19, figures 4.

Novel hybrid excited machine with flux barriers in rotor structure

2018 ◽  
Vol 37 (4) ◽  
pp. 1489-1499 ◽  
Author(s):  
Marcin Wardach ◽  
Ryszard Palka ◽  
Piotr Paplicki ◽  
Michal Bonislawski
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Control Method ◽  
Permanent Magnet Machines ◽  
Original Design ◽  
Element Analysis ◽  
Flux Control ◽  
Content Type ◽  
Field Weakening ◽  
Rotor Structure

Purpose Permanent magnet (PM) electrical machines are becoming one of the most popular type of the machines used in electrical vehicle drive applications. The main drawback of permanent magnet machines, despite obvious advantages, is associated with the flux control capability, which is limited at high rotor speeds of the machine. This paper aims to present a new arrangement of permanent magnets and flux barriers in the rotor structure to improve the field weakening control of hybrid excited machines. The field weakening characteristics, back-emf waveforms and efficiency maps of this novel machine have been reported. Design/methodology/approach In the study, finite element analysis was used to perform simulation research. Then, based on the simulation studies, an experimental model was built. The paper also presents selected experimental results. Findings Obtained results show that the proposed machine topology and novel control strategy can offer an effective flux control method allowing to extend the maximal rotational speed of the machine at constant power range. Practical implications The proposed solution can be used in electric vehicles drive to extend its torque and speed range. Originality/value The paper presents original design and results of research on a new solution of a hybrid excited machine with magnetic barriers in a rotor.

EM of rapidly solidified permanent magnets

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.

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

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.

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

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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