scholarly journals Design of dual rotor axial flux permanent magnet generators with ferrite and rare-earth magnets

2020 ◽  
Vol 33 (4) ◽  
pp. 553-569
Author(s):  
Jawad Faiz ◽  
Tohid Asefi ◽  
Mohammad Khan
Keyword(s):  
Rare Earth ◽  
Permanent Magnet ◽  
Three Dimensional ◽  
Torque Ripple ◽  
Population Based ◽  
Axial Flux ◽  
Energy Applications ◽  
Rotor Pole ◽  
Mass Minimization ◽  
Population Based Algorithm

This article addresses dual rotor axial flux Ferrite permanent magnet (PM) generator, as an alternative to a surface mounted and spoke types Nd-Fe-B generator which have concentrated windings. The performance parameters of all generators, particularly the efficiency, are identical. The design objective function is the generators mass minimization using a population-based algorithm. To predict the performance of the generators a finite element (FE) technique is applied. Besides, the aims of the design include minimizing cogging torque, examining different rotor pole topologies and different pole arc to pole pitch ratios. Three-dimensional FE technique is employed. It is shown that the surface mounted Ferrite generator topology cannot develop the rated torque and also has high torque ripple. In addition, it is heavier than the spoke type generator. Furthermore, it is indicated that the spoke type Ferrite PM generator has favorable performance and could be an alternative to rare-earth PM generators, particularly in wind energy applications. Finally, the performance of the designed generators is experimentally verified.

scholarly journals Design and Performance Assessment of a Small-Scale Ferrite-PM Flux Reversal Wind Generator

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5565
Author(s):  
Bharathi Manne ◽  
Malligunta Kiran Kumar ◽  
Udochukwu B. Akuru
Keyword(s):  
Rare Earth ◽  
Wind Energy ◽  
Permanent Magnet ◽  
Torque Ripple ◽  
Small Scale ◽  
Cogging Torque ◽  
Flux Reversal ◽  
Wind Generator ◽  
Rotor Pole ◽  
Flux Reversal Machine

Currently, there is increasing research interest in harnessing wind energy for power generation by means of non-conventional electrical machines e.g., flux-reversal machines. The flux reversal machine is usually designed using scarce rare–earth permanent magnet material which may be unattractive in terms of machine cost. In this study, an attempt is made to re-design the flux reversal machine with non-rare-earth ferrite permanent magnet for wind energy applications. Because these machines possess high cogging torque, which results in vibration and noise, that are detrimental to the machine performance, especially at low speeds, a novel combined skewed and circumferential rotor pole pairing method is developed. The proposed cogging torque reduction method is implemented in 2-dimensional finite element analysis modeling and comparatively analyzed with other existing stand-alone methods viz., skewing, and rotor pole pairing. The results show that the proposed method led to 94.8% and 71% reduction in the cogging torque and torque ripple compared to the reference generator, respectively. However, the calculated torque density is reduced by 13%. Overall, the electromagnetic performance of the proposed ferrite PM machine exhibits desirable qualities as an alternative design for the direct drive wind generator.

scholarly journals Design and Analysis of a Novel Axial-Radial Flux Permanent Magnet Machine with Halbach-Array Permanent Magnets

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3639
Author(s):  
Rundong Huang ◽  
Chunhua Liu ◽  
Zaixin Song ◽  
Hang Zhao
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Torque Ripple ◽  
Axial Flux ◽  
Element Analysis ◽  
Torque Density ◽  
Axial Forces ◽  
Halbach Array ◽  
Radial Flux ◽  
High Torque

Electric machines with high torque density are needed in many applications, such as electric vehicles, electric robotics, electric ships, electric aircraft, etc. and they can avoid planetary gears thus reducing manufacturing costs. This paper presents a novel axial-radial flux permanent magnet (ARFPM) machine with high torque density. The proposed ARFPM machine integrates both axial-flux and radial-flux machine topologies in a compact space, which effectively improves the copper utilization of the machine. First, the radial rotor can balance the large axial forces on axial rotors and prevent them from deforming due to the forces. On the other hand, the machine adopts Halbach-array permanent magnets (PMs) on the rotors to suppress air-gap flux density harmonics. Also, the Halbach-array PMs can reduce the total attracted force on axial rotors. The operational principle of the ARFPM machine was investigated and analyzed. Then, 3D finite-element analysis (FEA) was conducted to show the merits of the ARFPM machine. Demonstration results with different parameters are compared to obtain an optimal structure. These indicated that the proposed ARFPM machine with Halbach-array PMs can achieve a more sinusoidal back electromotive force (EMF). In addition, a comparative analysis was conducted for the proposed ARFPM machine. The machine was compared with a conventional axial-flux permanent magnet (AFPM) machine and a radial-flux permanent magnet (RFPM) machine based on the same dimensions. This showed that the proposed ARFPM machine had the highest torque density and relatively small torque ripple.

scholarly journals A Three-Dimensional Magnetic Force SolutionBetween Axially-Polarized Permanent-Magnet Cylinders for Different Magnetic Arrangements

2020 ◽  
Vol 7 ◽  
Keyword(s):  
Experimental Data ◽  
Rare Earth ◽  
Field Strength ◽  
Permanent Magnet ◽  
Magnetic Force ◽  
Three Dimensional ◽  
Method Of Images ◽  
Field Equations ◽  
Rare Earth Magnet ◽  
Finite Sums

A three-dimensional field solution is presented foraxially polarized permanent magnet cylinders. The fieldcomponents are expressed in terms of finite sums of elementaryfunctions and are easily programmable. They can be used todetermine the operating point of rare-earth magnet cylinders.They are also useful for performing rapid parametriccalculations of field strength as a function of materialproperties and dimensions. The field components aredeveloped for different magnet arrangements by taking intoaccount the back iron. Also the method of images is used. Usingthe field equations, three-dimensional analytical expressionsare derived for computing the magnetic force between axiallypolarized permanent-magnet cylinders for different magneticarrangements. The field calculated results are in goodagreement with the experimental data.

Torque ripple reduction of synchronous reluctance machines

2015 ◽  
Vol 34 (1) ◽  
pp. 3-17 ◽  
Author(s):  
K. Wang ◽  
Z.Q. Zhu ◽  
G. Ombach ◽  
M. Koch ◽  
S. Zhang ◽  
...  
Keyword(s):  
Permanent Magnet ◽  
Double Layer ◽  
Torque Ripple ◽  
Content Type ◽  
Synchronous Reluctance Machine ◽  
Barrier Layers ◽  
Reluctance Machine ◽  
Output Torque ◽  
Rotor Pole ◽  
Cage Induction Motor

Purpose – The purpose of this paper is to investigate the influence of stator and rotor pole number combinations together with the flux-barrier layers number on the performance of synchronous reluctance machine with emphasis on output torque capability and torque ripple. Design/methodology/approach – AC synchronous reluctance machine (SynRM) or permanent magnet assisted SynRM presently receives a great deal of interest, since there is less or even no rare-earth permanent magnet in the rotor. Most of SynRM machines employ a stator that is originally designed for a standard squirrel cage induction motor for a similar output rating and application, or the SynRM machine with 24-slot, four-pole are often directly chosen for investigation in most of the available literature. Therefore, it is necessary to investigate the influence of stator and rotor pole number combinations together with the flux-barrier layers number on the performance of SynRM machine with emphasis on output torque capability and torque ripple. Findings – The average torque decreases with the increase of the pole numbers but remain almost constant when employing different stator slot numbers but with the same pole number. In addition, the torque ripple decreases significantly with the increase of the stator slot number. The machine with double-layer flux-barrier in the rotor has the biggest average torque, while the machines with three- and four-layer flux-barrier in the rotor have almost the same average torque but their value is slightly smaller than that of machine with double-layer flux-barrier. However, the machine with three-layer flux-barrier has the lowest torque ripple but the highest torque ripple exists in the machine with double-layer flux-barrier. Research limitations/implications – The purely sinusoidal currents are applied in this analysis and the effects of harmonics in the current on torque ripple are not considered in this application. Originality/value – This paper has analyzed the torque ripple and average torque of SynRMs with considering slot/pole number combinations together with the flux-barrier number.

scholarly journals Comparison of Three Analytical Methods for the Precise Calculation of Cogging Torque and Torque Ripple in Axial Flux PM Machines

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Ahmed Hemeida ◽  
Bert Hannon ◽  
Hendrik Vansompel ◽  
Peter Sergeant
Keyword(s):  
Permanent Magnet ◽  
Lateral Force ◽  
Torque Ripple ◽  
Analytical Models ◽  
Permanent Magnet Synchronous Machines ◽  
Axial Flux ◽  
Cogging Torque ◽  
Precise Calculation ◽  
Analytical Tools ◽  
2D And 3D

A comparison between different analytical and finite-element (FE) tools for the computation of cogging torque and torque ripple in axial flux permanent-magnet synchronous machines is made. 2D and 3D FE models are the most accurate for the computation of cogging torque and torque ripple. However, they are too time consuming to be used for optimization studies. Therefore, analytical tools are also used to obtain the cogging torque and torque ripple. In this paper, three types of analytical models are considered. They are all based on dividing the machine into many slices in the radial direction. One model computes the lateral force based on the magnetic field distribution in the air gap area. Another model is based on conformal mapping and uses complex Schwarz Christoffel (SC) transformations. The last model is based on the subdomain technique, which divides the studied geometry into a number of separate domains. The different types of models are compared for different slot openings and permanent-magnet widths. One of the main conclusions is that the subdomain model is best suited to compute the cogging torque and torque ripple with a much higher accuracy than the SC model.

scholarly journals Performance Evaluation of a Permanent Magnet-Assisted Synchronous Reluctance Machine with Hybrid Magnets of Ferrite Magnets and Rare-earth PMs

2017 ◽  
Author(s):  
Xiping Liu ◽  
Ya Li ◽  
Zhangqi Liu
Keyword(s):  
Rare Earth ◽  
Permanent Magnet ◽  
Torque Ripple ◽  
Hybrid Magnet ◽  
Element Analysis ◽  
Cost Performance ◽  
Synchronous Reluctance Machine ◽  
Reluctance Machine ◽  
Output Torque ◽  
Loss Efficiency

In this paper, a novel permanent magnet-assisted synchronous reluctance machine (PMASynRM) with rare-earth PMs and ferrite magnets is proposed. The performance of PMASynRM is discussed with respected to the different magnet ratio of rare-earth PMs and ferrite magnets. Some characteristics including the flux density, output torque, cogging torque, output power, power factor, torque ripple, loss, efficiency, and demagnetization are calculated by 2-D finite element analysis (FEA). The analysis results show that the excellent performance can be obtained by using hybrid magnet of rare-earth PMs and ferrite magnets with the suitable magnet ratio, and provide some desirable cost-performance trade-off.

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