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Article
Publication date: 9 November 2023

Mohammadhossein Arianborna, Jawad Faiz, Mehrage Ghods and Amirhossein Erfani-Nik

The aim of this paper is to introduce an accurate asymmetric fault index for the diagnosis of the faulty linear permanent magnet Vernier machine (LPMVM).

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Abstract

Purpose

The aim of this paper is to introduce an accurate asymmetric fault index for the diagnosis of the faulty linear permanent magnet Vernier machine (LPMVM).

Design/methodology/approach

Three-dimensional finite element method is applied to model the LPMVM. The geometrical and physical properties of the machine, the effect of stator and translator teeth, magnetic saturation of core and nonuniform air gap due to asymmetric fault are taken into account in the simulation. The air gap asymmetric fault is proposed. This analytical method estimates the air gap flux density of an LPMVM.

Findings

This paper presents an analytical method to predict the performance of a healthy and faulty LPMVM. The introduced index is based on the frequency patterns of the stator current. Besides, the robustness of the index in different loads and fault severity is addressed.

Originality/value

Introducing index for air gap asymmetry fault diagnosis of LPMVM.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 42 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 28 March 2019

Jawad Faiz and Farhad Rezaee-Alam

The purpose of this paper is to present an improved winding function theory (IWFT) for performance analysis of surface mounted permanent magnet (SMPM) motors, which can precisely…

164

Abstract

Purpose

The purpose of this paper is to present an improved winding function theory (IWFT) for performance analysis of surface mounted permanent magnet (SMPM) motors, which can precisely and simultaneously consider the impacts of stator slotting, the winding distribution, the magnetic flux density within PMs because of the armature reaction, the PM magnetization angle and the magnetic saturation,.

Design/methodology/approach

To obtain this improved analytical model, the conformal mappings (CMs) are introduced to calculate the relative complex permeance of slotted air-gap, which is used to obtain the function of slotted air-gap length. The equivalent magnetizing current model is used to extract the equivalent winding function for each PM pole. For retaining the basic assumption of WFT, the magnetic saturation is also considered by a proper increase in the air-gap length in the front of the stator teeth.

Findings

A new hybrid analytical model (HAM) based on WFT is presented in this paper, which can simultaneously and accurately consider the effects of slotting, the magnetic saturation, the variation of PM operating point and the winding distribution. In fact, IWFT removes all the drawbacks of the conventional WFT. Moreover, IWFT is more user-friendly and faster than other analytical and numerical techniques.

Practical implications

The obtained HAM can be used for design, optimization and fault diagnosis in electric machines.

Originality/value

This paper presents a new HAM for accurate modeling the SMPM motors, which includes different considerations of electromagnetic modeling. This new HAM can also be used for modeling the other electric motors.

Details

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

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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 distribution in…

219

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

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Article
Publication date: 1 March 2000

Jawad Faiz and John W. Finch

Method of unaligned permeance determination for a doubly‐salient rectilinear airgap with infinite slot depth is used in order to cover a wider range of gap geometry. The results…

363

Abstract

Method of unaligned permeance determination for a doubly‐salient rectilinear airgap with infinite slot depth is used in order to cover a wider range of gap geometry. The results are arranged in a more convenient form than is available in the literature. A set of new correction factor curves for finite slot depth and taper are then obtained. These data can directly give the unaligned permeance of a rectilinear slotted geometry for given airgap proportions (t/λ and λ/g, where λ is the tooth pitch, t is the tooth width and g is the airgap length). A wide and useful range of airgap proportions are covered, the aim having been to encompass all geometries likely to be of practical importance.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 December 2001

Jawad Faiz and M.B.B. Sharifian

This paper presents various available and new techniques for prediction of the hysteresis loop, no‐load current curve and hysteresis losses. It is shown that linearization is a…

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Abstract

This paper presents various available and new techniques for prediction of the hysteresis loop, no‐load current curve and hysteresis losses. It is shown that linearization is a convenient method to be employed for quick estimation of the hysteresis loop with acceptable accuracy. Although the third and fifth order functions for saturation curve prediction lead to more accurate results, it requires more data and also more complicated equations resulting in longer computation time. Use of various third and fifth order functions for saturation curve are the noticeable advantages of the techniques. The three proposed techniques could predict the hysteresis loop of transformers using simple experiments and iterative computer computations.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 20 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 March 2000

Jawad Faiz and John W. Finch

Effect of slot depth on the evaluation of permeance in the aligned position for identically slotted rectilinear tooth geometry can be carried out using conformal transformations…

332

Abstract

Effect of slot depth on the evaluation of permeance in the aligned position for identically slotted rectilinear tooth geometry can be carried out using conformal transformations. Consequent increase of permeance is related to the airgap proportion ratios; tooth‐width to tooth‐pitch, t/λ; tooth‐pitch to airgap dimension, λ/g; and slot‐depth to slot‐d/s; through two intermediate parameters. Efficient search routine is used to find a suitable combination of these two parameters corresponding to given proportions of tooth and slot. For λ/g larger than 80 and d/s between 0.3 and 1, the effect of slot depth is negligible, but for λ/g equal to or less than 80 a family of permeance correction factor curves is obtained which may be used to correct for finite slot depth in permeance calculations based on infinitely deep slots. This effect is important in stepping and switched reluctance motors, particularly those with multiple teeth per stator pole.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 February 1998

Jawad Faiz and Mansour Ojaghi

In this paper, different shapes of the boundary surfaces within the power transformers are reviewed. The surface charge distribution function on the two surface elements, which…

315

Abstract

In this paper, different shapes of the boundary surfaces within the power transformers are reviewed. The surface charge distribution function on the two surface elements, which have the majority of usage, are recognized and the resultant potential and electric field intensity equations are derived. A numerical interpolation idea is presented and extended to evaluate the values of the existing integrals within the equations. Fulfilment of this idea removes the problems due to the singularity of the integrands and it leads to a shorter computation time for the boundary element method. This idea is applied to a typical problem and results are compared with the corresponding values obtained using the numerical integration. Finally, the electric field within the interior space of a power transformer is estimated using the developed computer program based on the boundary element method.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 17 no. 1
Type: Research Article
ISSN: 0332-1649

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Expert briefing
Publication date: 5 February 2016

Foreign ministers from 23 countries met in Rome on February 2 to discuss responses to the Islamic State group (ISG). The meeting was held amid a steady stream of statements from…

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Article
Publication date: 4 January 2011

Estelle Dryland and Jawad Syed

The aim of this paper is to explore issues of cultural identity of the people of Baltistan and any challenges they face in the nation state of Pakistan.

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Abstract

Purpose

The aim of this paper is to explore issues of cultural identity of the people of Baltistan and any challenges they face in the nation state of Pakistan.

Design/methodology/approach

The paper uses a postcolonial lens to offer a review and synthesis of issues of cultural identity of the Balti people of Pakistan.

Findings

The review demonstrates how the historical and socio‐political context is intertwined with the Balti people's cultural identity which remains hybrid as well as contextual in its construction. It reveals that while the state of Pakistan has been able to assert its control over the Balti people and the region of Baltistan predominantly through military means, the critical issues of cultural pluralism and the basic human rights of the Balti people have remained generally ignored throughout the 63 years since partition.

Research limitations/implications

The contentions offered in this paper need to be refined through in‐depth empirical studies. Future scholars may wish to examine the class and cultural politics at work in the emerging renaissance movement in Baltistan. Scholars may also examine how the lack of economic development and investment in Baltistan may be forcing the Balti people to resign (at least some elements of) their cultural identity to seek employment in urban areas of Pakistan.

Originality/value

The paper brings to the fore issues of cultural identity of the people of Baltistan, which have – to a large extent – remained ignored by Pakistan as well as internationally.

Details

Equality, Diversity and Inclusion: An International Journal, vol. 30 no. 1
Type: Research Article
ISSN: 2040-7149

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