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Article
Publication date: 1 January 2013

Imen Abdennadher and Ahmed Masmoudi

The paper is aimed at the investigation of the magnetic forces generated by fractional slot surface mounted PM machines, considering a comparative study between two…

Abstract

Purpose

The paper is aimed at the investigation of the magnetic forces generated by fractional slot surface mounted PM machines, considering a comparative study between two topologies: a 9 slot/10 pole machine and a 12 slot/10 pole machine.

Design/methodology/approach

Following the distribution of the armature windings using the star of slots approach, an investigation of the magnetic forces developed by both machines under study, using 3D finite element analysis (FEA). Prior to such investigation, a 2D FEA based sizing procedure is carried out in order to select a set of suitable geometrical parameters. Then, the comparison between both machines is extended to the torque production capability.

Findings

It has been found that the 9 slot/10 pole machine has a pic value of the average magnetic force reaching almost 40N which is located in one side of the air gap. Such a peak does not exceed 7N in the 12 slot/10 pole machine and is located in two diametrically‐opposite areas of the air gap.

Research limitations/implications

This work should be extended by an experimental validation of the FEA results regarding the magnetic force generation.

Practical implications

The list of the selection criteria of fractional slot PM machines should be extended to the magnetic force generation in order to fulfil the requirements of many applications such as the propulsion systems.

Originality/value

The paper proposes a combined electromagnetic‐mechanical approach to investigate the magnetic forces generated by fractional slot surface mounted PM machines using 2D and 3D finite element analysis.

Details

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

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Article
Publication date: 13 November 2009

Ayman M. EL‐Refaie, Z.Q. Zhu, Thomas M. Jahns and David Howe

Permanent magnet (PM) brushless machines equipped with fractional‐slot concentrated‐windings (FSCW) have been receiving considerable attention over the past few years, due…

Abstract

Purpose

Permanent magnet (PM) brushless machines equipped with fractional‐slot concentrated‐windings (FSCW) have been receiving considerable attention over the past few years, due to the fact that they have short end‐windings, a high‐slot fill factor, a high efficiency and power density, and good flux‐weakening and fault‐tolerance capabilities. A key design parameter for such machines is the phase winding inductance since this has a significant impact on the performance, as well as on the magnitude of any reluctance torque. The purpose of this paper is to describe a detailed investigation of the various components of the winding inductance in machines equipped with both overlapping and non‐overlapping windings and different slot/pole number combinations. It also examines the influence of key design parameters, which affect the inductance components, with particular reference to the inductances of machines in which all the teeth are wound and those in which only alternate teeth are wound.

Design/methodology/approach

The paper analyzes and compares various inductance components which result from different winding configurations.

Findings

It is shown that the main component of the winding inductance is the relatively large slot‐leakage component. Both analytical and finite element models are employed and predicted results are validated on several prototype machines.

Originality/value

Such a thorough investigation of the various inductance components for these type of machines has not been presented before. The paper will serve as a good reference for engineers and researchers designing PM machines equipped with FECW.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 5 January 2015

K. Wang, Z.Q. Zhu, G. Ombach, M. Koch, S. Zhang and J. Xu

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…

Abstract

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.

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

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Case study
Publication date: 20 January 2017

Kent Grayson and Elliot Freeman

CEO Richard Gedman has suddenly found himself running two separate but potentially related businesses: the slot manufacturing and marketing business that he has been…

Abstract

CEO Richard Gedman has suddenly found himself running two separate but potentially related businesses: the slot manufacturing and marketing business that he has been running for years, and a new online and mobile gaming business that has grown incredibly fast over the past couple of years. To sustain success in both businesses, it seems clear that each one will require significant R&D investments. Should he invest in only one or both?

After students analyze the case, they will have a greater appreciation for why successful marketing requires a true understanding of customers and their preferences, rather than (for example) merely examining competitor offerings. They will also have a clearer understanding of how to calculate some of the basic metrics needed to do a marketing analysis (e.g., market share, price per unit) and how these metrics can inform any marketing decisions significantly.

Details

Kellogg School of Management Cases, vol. no.
Type: Case Study
ISSN: 2474-6568
Published by: Kellogg School of Management

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Article
Publication date: 1 February 2013

Sandy C. Chen, Stowe Shoemaker and Dina Marie V. Zemke

Slot machines and other machine gaming generate between 65 percent and 90 percent of a US casino's revenue. This article aims to examine the motivations, behaviors, and…

Abstract

Purpose

Slot machines and other machine gaming generate between 65 percent and 90 percent of a US casino's revenue. This article aims to examine the motivations, behaviors, and preferences of slot machine customers, and to develop market segments.

Design/methodology/approach

The study's objectives include: understanding the demographic, gambling motivation, and gambling behavioral characteristics of slot machine players; identifying important reasons for choosing one slot machine game over another; examining player attitudes and behaviors pertaining to progressive machines; and investigating player desire for theme‐based games. This was accomplished through an online survey of slot machine players.

Findings

Profiles of slot machine players are developed and the slot players are segmented into four clusters that explain motivations and game preferences.

Practical implications

This article fills in some of the gaps in understanding the gambling behavior of slot players. This study can help gaming machine manufacturers design new products and features to serve existing machine gaming customers and to attract new customers. Casino and other gaming operators can use this information not only to select the right types of machines to provide on‐site, but also to develop advertising and promotions to attract and retain new and existing customers for slot machines and other types of gaming machines.

Originality/value

This is the first published study that segments slot machine players from a marketing perspective and identifies their preferences, behaviors, and demographic groupings.

Details

International Journal of Contemporary Hospitality Management, vol. 25 no. 1
Type: Research Article
ISSN: 0959-6119

Keywords

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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…

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

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Article
Publication date: 1 January 2012

Ayman EL‐Refaie and Manoj Shah

The purpose of the paper is to investigate the performance of induction machines with fractional‐slot concentrated‐windings.

Abstract

Purpose

The purpose of the paper is to investigate the performance of induction machines with fractional‐slot concentrated‐windings.

Design/methodology/approach

This paper examines induction machine performance with fractional‐slot concentrated windings using the standard distributed lap windings as reference. Four designs are compared and various performance tradeoffs highlighted. The first machine has integral‐slot distributed 2 slots/pole/phase lap winding and it serves as the reference winding. The second machine has a double‐layer 1/2 slot/pole/phase winding, a workhorse for brushless DC machines. The third machine has double‐layer 2/5 slot/pole/phase winding. Lastly, the fourth machine has single‐layer 2/5 slot/pole/phase windings. The comparison includes torque‐speed curves (including the effects of major space harmonic components), rotor bar losses, and ripple torque levels.

Findings

Based on the analysis results presented here, the traditional distributed lap winding is proven to be superior to FSCW in terms of torque production and rotor bar losses for induction machine applications. The 1/2 spp shows some promising results in terms of torque production, in addition to significant reduction and simplification of end turns with lower number of coils albeit with more turns/coil (12 slots vs 48 slots). The penalty is the additional rotor bar losses due to the 2nd and 4th harmonic mmf components. The 2/5 spp is not promising for torque production and should be avoided. The transient simulation results that simultaneously take into account the effects of all space harmonics and magnetic saturation showed comparable trends compared to the harmonic analysis results. It has also been shown that FSCW tend to have higher torque ripple compared to distributed windings.

Originality/value

To the best of the authors' knowledge, this paper for the first time attempts to quantitatively address the tradeoffs involved in using FSCW in induction machines.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 4 January 2011

Jin‐Tao Chen and Zi‐Qiang Zhu

The purpose of this paper is to analyze the phase coil connections and winding factors of flux‐switching permanent magnet (FSPM) brushless AC machines with all poles and…

Abstract

Purpose

The purpose of this paper is to analyze the phase coil connections and winding factors of flux‐switching permanent magnet (FSPM) brushless AC machines with all poles and alternate poles wound, and different combinations of stator and rotor pole numbers.

Design/methodology/approach

The coil‐emf vectors, which are widely used for analyzing the conventional fractional‐slot PM machines with non‐overlapping windings, are employed for FSPM machines.

Findings

Although the coil‐emf vectors have been employed to obtain coil connections in the conventional fractional‐slot PM machines, they are different in FSPM machines. It is mainly due to different polarities in the stator of FSPM machines. In addition, from the coil‐emf vectors it is able to predict whether the back‐emf waveforms are symmetrical or asymmetric.

Originality/value

This is the first time that coil‐emf vectors are used to determine the coil connections and winding factors in FSPM machines with different topologies and combination of stator and rotor pole numbers.

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

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Article
Publication date: 30 April 2019

Jawad Faiz, Mohammadreza Hassanzadeh and Arash Kiyoumarsi

This paper aims to present an analytical method, which combines the complex permeance (CP) and the superposition concept, to predict the air-gap magnetic field…

Abstract

Purpose

This paper aims to present an analytical method, which combines the complex permeance (CP) and the superposition concept, to predict the air-gap magnetic field distribution in surface-mounted permanent-magnet (SMPM) machines with eccentric air-gap.

Design/methodology/approach

The superposition concept is used twice; first, to predict the magnetic field distribution in slot-less machine with eccentric air-gap, the machine is divided into a number of sections. Then, for each section, an equivalent air-gap length is determined, and the magnetic field distribution is predicted as a concentric machine model. The air-gap field in the slot-less machine with eccentricity can be combined from these concentric models. Second, the superposition concept is used to find the CP under eccentricity fault. At this end, the original machine is divided into a number of sections which may be different from the one for slot-less magnetic field prediction, and for each section, the CP is obtained by equivalent air-gap length of that section. Finally, the air-gap magnetic field distribution is predicted by multiplying the slot-less magnetic field distribution and the obtained CP.

Findings

The radial and tangential components of the air-gap magnetic flux density are obtained using the proposed method analytically. The finite element analysis is used to validate the proposed method results, showing good agreements with the analytical results.

Originality/value

This paper addresses the eccentricity fault impact upon the air-gap magnetic field distribution of SMPM machines. This is done by a combined analysis of the complex permeance (CP) method and the superposition concept. This contrasts to previous studies which have instead focused on the subdomain method.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 38 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 1 June 1930

H.B. Irving

THERE is little doubt at the present time as to the great advance in safety which the invention of the automatic slot has brought to the aeroplane. It has been the means…

Abstract

THERE is little doubt at the present time as to the great advance in safety which the invention of the automatic slot has brought to the aeroplane. It has been the means of overcoming one of its chief failings, the loss of stability and control at the stall. Automatic slots at the wing tips are themselves capable of converting an aeroplane which is unstable in roll at incidences beyond the stall into one which is definitely stable; at the same time the aileron control is increased and improved in that its application is not accompanied by so great an adverse yawing moment as for ailerons working on an unslotted wing. Further, if some form of interconnection between ailerons and slots is adopted, or some device (e.g. the “interceptor”), by means of which the action of the slot can be spoiled, a further big addition to the control at the stall can be made as well as further improvement in the shape of a reversal of the usual yawing moment. Whether such addition is desirable for all types of machine remains to bo seen; it may be that in certain types the automatic slots alone, without interconnection, will provide all the increase in stability and control at the stall which is required.

Details

Aircraft Engineering and Aerospace Technology, vol. 2 no. 6
Type: Research Article
ISSN: 0002-2667

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