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Article
Publication date: 5 October 2022

Qiang Zhao and Xu Liu

The purpose of this study is to develop a novel mechanical flux-weakening topology for the switched flux permanent magnet (SFPM) machine to extend the speed range, which will be…

Abstract

Purpose

The purpose of this study is to develop a novel mechanical flux-weakening topology for the switched flux permanent magnet (SFPM) machine to extend the speed range, which will be suitable for the electric vehicles and hybrid electric vehicles.

Design/methodology/approach

The 3 dimensional mechanical flux-weakening model with flux adjusters (FAs) in the end-cap is established. Subsequently, the electromagnetic performance is compared between the SFPM machine with FAs in the end-cap and without FAs. The open circuit flux-linkage is calculated by finite element analysis (FEA) to investigate the influence of this mechanical flux-weakening topology together with the d/q-axis inductance. The flux-weakening capability and torque-speed curve is also calculated.

Findings

The proposed topology decreases the permanent magnet flux-linkage and increases the d-axis inductance, which improve the flux-weakening capability simultaneously. Subsequently, the speed range and constant power region are much wider than those without FAs. Finally, the prototype is fabricated and the measured result of the open circuit back electromotive force has good agreement with the FEA result.

Originality/value

This paper provides a novel mechanical flux-weakening topology with FAs in the end-cap for the SFPM machine, whose volume is smaller than another mechanical flux-weakening topology with FAs at the stator outside. Thus, higher torque and power density can be obtained compared with the SFPM machine with FAs at the stator outside.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 42 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 26 August 2014

K. Wang, Z.Q. Zhu, G. Ombach and W. Chlebosz

The purpose of this paper is to investigate torque ripple and magnetic force on the teeth in interior permanent magnet (IPM) machines over a wide range of speed operation for…

Abstract

Purpose

The purpose of this paper is to investigate torque ripple and magnetic force on the teeth in interior permanent magnet (IPM) machines over a wide range of speed operation for electrical power steering (EPS) applications.

Design/methodology/approach

The flux-weakening capability of IPM machines has been analysed by finite element method considering the effect of cross-coupling between d- and q-axis current. The traditional method of analysing torque ripple is based on constant torque and flux-weakening region. However, the cross-coupling need to be considered when applying this technique to flux-weakening region. Meanwhile, the torque ripple with current amplitude and angle and with different speed in the flux-weakening region is also investigated. In addition, the magnetic force on the teeth due to the separated teeth with stator yoke is also investigated during the constant torque and flux-weakening region.

Findings

The torque ripple and magnetic force on teeth in IPM machine are dependent on current and current angle. Both the lowest torque ripple and magnetic force on teeth exist over the whole torque-speed region.

Research limitations/implications

The purely sinusoidal currents are applied in this analysis and the effects of harmonics in the current on torque ripple and magnetic force on teeth are not considered in this application. The 12-slot/10-pole IPM machine has been employed in this analysis, but this work can be continued to investigate different slot/pole number combinations.

Originality/value

This paper has analysed the torque ripple and magnetic force on the teeth in IPM machines for EPS application over a wide range of operation speed, which are the main cause of vibration and acoustic noise. The variation of torque ripple with current amplitude and angle as well as speed in the flux-weakening region is also investigated. In addition, the magnetic force on the teeth is also investigated over the whole torque-speed region.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 January 2013

Massimo Barcaro and Nicola Bianchi

The purpose of this paper is to give an overview of the design issues of permanent magnet machines for the hybrid electric and plug‐in electric vehicles, including railway…

Abstract

Purpose

The purpose of this paper is to give an overview of the design issues of permanent magnet machines for the hybrid electric and plug‐in electric vehicles, including railway traction and naval propulsion.

Design/methodology/approach

Focus is given on both synchronous permanent magnet and reluctance machines. An overview of the design rules are provided, covering the topics of: fractional‐slot windings, fault‐tolerant configurations, flux‐weakening capability, and torque quality.

Findings

The peculiarities of these machines and the advanced design considerations to fit the automotive requirements are analyzed.

Originality/value

The paper includes a wide description of innovative electrical machines for electric vehicles, including not only the traction capability, but also analysis of features as weight reduction, torque ripple reduction, increase of fault tolerance, and so on.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 5 January 2015

Asma Masmoudi and Ahmed Masmoudi

The purpose of this paper is to compare the study between two topologies of fractional-slot permanent-magnet machines such that: double-layer topology and single-layer one. The…

Abstract

Purpose

The purpose of this paper is to compare the study between two topologies of fractional-slot permanent-magnet machines such that: double-layer topology and single-layer one. The comparison considers the assessment of the iron loss in the laminated cores of the magnetic circuit as well as in the permanent magnets (PMs) for constant torque and flux weakening ranges.

Design/methodology/approach

The investigation of the hysteresis and eddy-current loss has been carried out using 2D transient FEA models.

Findings

It has been found that the stator iron losses are almost the same for both topologies. Whereas, the single-layer topology is penalized by higher iron loss especially the eddy-current ones taking place in the PMs. This is due to their denser harmonic content of the armature air gap MMF spatial repartition.

Originality/value

The analysis of the iron loss maps in different parts of each machine including stator and rotor laminations as well as the PMs, in one hand, and the investigation of their variation with respect to the speed, in the other hand, represent the major contribution of this work.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 March 2016

M,M.J, Al-ani and Z.Q. Zhu

The purpose of this paper is to investigate and compare the influence of end-effect on the torque-speed characteristics of three conventional switched flux permanent magnet (SFPM…

Abstract

Purpose

The purpose of this paper is to investigate and compare the influence of end-effect on the torque-speed characteristics of three conventional switched flux permanent magnet (SFPM) machines having different stator/rotor pole combinations, i.e. 12/10, 12/13 and 12/14 as well as three novel topologies with less permanent magnets (PMs), i.e. multi-tooth, E-core and C-core.

Design/methodology/approach

SFPM machines combine the advantages of simple and robust rotor and easy management of the temperature due to the location of the PMs and armature windings on the stator. However, due to spoke location of the PMs a large flux leakage in the end region, i.e. end-effect, can be observed which could result in a large reduction in the electromagnetic performance. Therefore, the influence of end-effect on the torque-speed characteristics is investigated. 3D-finite element analyses (FEA) results are compared with their 2D-FEA counterparts in order to account for the end-effect influence.

Findings

It has been concluded that due to end flux leakage, lower torque capability in the constant torque region is observed in the six machines. However, improved flux-weakening capability in the conventional machines can be exhibited at high current levels, whereas due to the large inductance lower power capability in the multi-tooth, E-core and C-core machines is obtained.

Research limitations/implications

The influence of temperature rise on the performance is not included.

Originality/value

This paper has analysed the influence of end-effect on the torque-speed characteristics of several SFPM machines.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 March 2016

D. Wu, Z.Q. Zhu and X. Liu

The purpose of this paper is to propose the design concepts of external rotor switched flux hybrid magnet memory machine (SFHMMM) to further increase the torque capability while…

Abstract

Purpose

The purpose of this paper is to propose the design concepts of external rotor switched flux hybrid magnet memory machine (SFHMMM) to further increase the torque capability while keeping the merits of internal rotor SFHMMM, such as adjustable back-EMF, and good flux weakening performance, etc.

Design/methodology/approach

The torque enhancing principle of external rotor SFHMMM, and the design considerations such as feasible stator and rotor pole numbers (Ns/Nr ) are discussed by equations. Then, the performances such as back-EMF, dq-axis inductances, torque and flux weakening performances are calculated and compared with the aid of finite element analysis software.

Findings

The external rotor SFHMMMs have obviously larger torque capabilities compared with the internal rotor ones under the same copper loss and machine size. The main reason is that the external SFHMMs could fully utilize the inner space of stator, which offers higher slot area, larger split ratio and consequently the higher average torque. For the external rotor machines with larger rotor pole number Nr , the back-EMF adjust ratio as well as the maxim torque are better. However, leakage flux and losses also increase with Nr due to limited machine size and higher operation frequency. Considering torque capability and flux weakening performance (efficiency map), the external SFHMMM with Nr =2Ns +1, e.g. 6/13 Ns/Nr stator/rotor pole machine, is the optimal choice.

Originality/value

This paper introduces the design concept and design considerations of external SFHMMM for the first time. The proposed machine could be a competent candidate for direct-drive electric vehicle applications.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 4 January 2011

Zi‐Qiang Zhu

Fractional slot permanent magnet (PM) brushless machines having concentrated non‐overlapping windings have been the subject of research over last few years. They have already been…

1491

Abstract

Purpose

Fractional slot permanent magnet (PM) brushless machines having concentrated non‐overlapping windings have been the subject of research over last few years. They have already been employed in the commercial hybrid electric vehicles (HEVs) due to high‐torque density, high efficiency, low‐torque ripple, good flux‐weakening and fault‐tolerance performance. The purpose of this paper is to overview recent development and research challenges in such machines in terms of various structural and design features for electric vehicle (EV)/HEV applications.

Design/methodology/approach

In the paper, fractional slot PM brushless machines are overviewed according to the following main and sub‐topics: first, machine topologies: slot and pole number combinations, all and alternate teeth wound (double‐ and single‐layer windings), unequal tooth structure, modular stator, interior magnet rotor; second, machine parameters and control performance: winding inductances, flux‐weakening capability, fault‐tolerant performance; and third, parasitic effects: cogging torque, iron loss, rotor eddy current loss, unbalanced magnetic force, acoustic noise and vibration.

Findings

Many fractional slot PM machine topologies exist. Owing to rich mmf harmonics, fractional slot PM brushless machines exhibit relatively high rotor eddy current loss, potentially high unbalanced magnetic force and acoustic noise and vibration, while the reluctance torque component is relatively low or even negligible when an interior PM rotor is employed.

Originality/value

This is the first overview paper which systematically reviews the recent development and research challenges in fractional‐slot PM machines. It summarizes their various structural and design features for EV/HEV applications.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 March 2016

I.A.A. Afinowi, Z.Q. Zhu, Y. Guan, Jean-Claude Mipo and P. Farah

– The purpose of this paper is to comparatively study the conventional, i.e. single magnet, and novel hybrid-magnet switched-flux permanent-magnet (HMSFPM) machines.

Abstract

Purpose

The purpose of this paper is to comparatively study the conventional, i.e. single magnet, and novel hybrid-magnet switched-flux permanent-magnet (HMSFPM) machines.

Design/methodology/approach

The HMSFPM machines utilize two magnet types, i.e. low-cost ferrites and NdFeB. Thus, a set of magnet ratios (?), defined as the quotient of the NdFeB volume to the total PM volume, is introduced. This allows any desired performance and cost trade-off to be designed. Series- and parallel-excited magnet configurations are investigated using 2-dimensional finite element analysis.

Findings

The torque of the HMSFPM machines is lower than the NdFeB SFPM machine but the flux-weakening performance is improved for similar machine efficiency. If the machine dimensions are unconstrained, the HMSFPM machines can have the same torque for reduced material costs and a moderate increase in machine dimensions. Ferrite SFPM machines have the lowest cost for the same torque but a significant increase in machine dimensions is required. Finally, the series-excited HMSFPM machine is the preferred over the parallel-excited HMSFPM machine because it has superior demagnetization withstand capability.

Research limitations/implications

Mechanical and winding eddy current losses are not considered in the efficiency map calculations.

Originality/value

The NdFeB SFPM, ferrite SFPM, series-excited HMSFPM, and the parallel-excited HMSFPM machines are compared for their electromagnetic performance, flux-weakening, PM demagnetization, efficiency, and material costs.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 26 August 2014

Imen Abdennadher and Ahmed Masmoudi

The purpose of this paper is to investigate the magnetic forces generated by a 12 slot/10 pole concentrated winding PM machines, considering a comparative study between two…

Abstract

Purpose

The purpose of this paper is to investigate the magnetic forces generated by a 12 slot/10 pole concentrated winding PM machines, considering a comparative study between two topologies: a surface mounted permanent magnet (SPM) machine and an interior PM (IPM) machine.

Design/methodology/approach

Following a description of the main characteristics of the concentrated winding permanent magnet machines (CWPMMs) under comparison, an investigation of the magnetic forces developed by both machines under study is carried out using finite element analysis (FEA).

Findings

A 2D FEA-based investigation has highlighted that the SPM machine develops higher magnetic forces than the IPM one. However, and following a 3D FEA, it has been found that the distribution of the magnetic forces along the air gap of the SPM machine is almost homogenous while it is concentrated in two opposite positions in the air gap of the IPM machine.

Research limitations/implications

This work has treated almost all features of the machines under comparison, except the power losses. These should be investigated with emphasis on the PM eddy current losses is so far as the harmonic content of the armature air gap MMF is high.

Practical implications

The list of the selection criteria of CWPMMs should be extended to the magnetic force cancellation in order to fulfill the requirements of many applications such as the automotive ones.

Originality/value

The paper proposes a combined electromagnetic-mechanical approach to investigate the magnetic forces generated by CWPMMs using 2D and 3D FEA.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 12 September 2008

Ayman M. EL‐Refaie and Thomas M. Jahns

The purpose of this paper is to provide a comparison of synchronous permanent magnet machine types for wide constant power speed range operation.

1303

Abstract

Purpose

The purpose of this paper is to provide a comparison of synchronous permanent magnet machine types for wide constant power speed range operation.

Design/methodology/approach

A combination of analytical models and finite element analysis is used to conduct this study.

Findings

The paper has presented a detailed comparison between various types of synchronous PM machines for applications requiring a wide speed range of constant‐power operation. Key observations include: surface permanent magnet (SPM) and interior permanent magnet (IPM) machines can both be designed to achieve wide speed ranges of constant‐power operation. SPM machines with fractional‐slot concentrated windings offer opportunities to minimize machine volume and mass because of their short winding end turns and techniques for achieving high‐slot fill factors via stator pole segmentation. High back‐emf voltage at elevated speeds is a particular issue for SPM machines, but also poses problems for IPM machine designs when tight maximum limits are applied. Magnet eddy‐current losses pose a bigger design issue for SPM machines, but design techniques can be applied to significantly reduce the magnitude of these losses. Additional calculations not included here suggest that the performance characteristics of the inverters accompanying each of the four PM machines are quite similar, despite the differences in machine pole number and electrical frequency.

Research limitations/implications

The paper is targeting traction applications where a very wide speed range of constant‐power operation is required.

Practical implications

Results presented are intended to provide useful guidelines for engineers faced with choosing the most appropriate PM machine for high‐constant power speed ratio applications. As in most real‐world drive design exercises, the choice of PM machine type involves several trade‐offs that must be carefully evaluated for each specific application.

Originality/value

The paper provides a comprehensive comparison between different types of synchronous PM machines, which is very useful in determining the most suitable type for various applications.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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