Jawad Faiz

Jawad Faiz
University of Tehran | UT · School of Electrical and Computer Engineering

Professor

About

423
Publications
215,368
Reads
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8,396
Citations
Citations since 2016
135 Research Items
4757 Citations
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
Additional affiliations
January 2005 - December 2009
University of Tehran

Publications

Publications (423)
Chapter
Condition monitoring in electrical machines, particularly in synchronous generators, has increased considerably in recent years. This chapter investigates the different fault types encountered in synchronous generators and the reasons for the creation of these faults. The health of a synchronous generator, and the origins of the faults depend on th...
Chapter
Accurate fault detection and condition monitoring, in addition to the machine rating power, depend on the salient pole synchronous generator topology. Data acquisition is one of the main steps in the fault detection procedure for generators. The data can be measured by: oscilloscope and data acquisition device. This chapter provides a practical app...
Chapter
A precise description of any power system dynamic performance requires accurate modeling of synchronous generators. The available parameters of the synchronous generators vary non‐linearly, depending on the environment temperature and operating conditions. Multi‐phase synchronous generator modeling has received less attention in the relevant litera...
Chapter
Design and analysis of electrical generators is a multi‐disciplinary process, generally comprising electromagnetic, thermal, and mechanical analysis in a highly repetitive process. Analysis of the thermal aspects of synchronous generators using existing methods can generally be divided into analytical and numerical methods. Several analytical and n...
Chapter
This chapter explores the use of signal processing in fault detection, and provides a concise description of “signal”. It provides a brief introduction to the advanced signal processing tools that have already been used in fault diagnosis. In a modern analog‐to‐digital conversion, the effects are mainly dominated by analog noise. The frequency at w...
Chapter
In recent years, the current signal analysis has been used to interpret the partial discharge (PD) signals due to greater advances in electronics, sampling, and signal recording. This chapter discusses the method of using these three techniques for the PD interpretation. One of the most critical steps in electrical measurement of the PD is choosing...
Chapter
Faults in synchronous generators are divided into electrical faults and mechanical faults. This chapter describes the mechanical faults which include: eccentricity faults; misalignment fault; broken damper bar fault; broken end ring fault; stator core deformation; stator core interlaminar fault; and stator core joint fault. Numerous eccentricity fa...
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The modeling of electrical machines typically employs an analytical method based on the winding function or its magnetic equivalent circuit. Other numerical techniques, such as finite difference, boundary element, and finite element (FEM) methods, have also been adopted. This chapter provides a better understanding of FEM, synchronous machine model...
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The finite element method provides a deep understanding of the magnetic behavior of electrical machines. Its use requires solving the Maxwell and Poisson equations in a combination of difficult boundary conditions related to the complicated geometry of the electrical machines. The winding function approach, or modified winding function method, is o...
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Machine learning as part of artificial intelligence is capable of tackling the solution to a problem without being specifically programmed. It can be classified into supervised, unsupervised, and reinforcement types. Weak learners may have poor performance in generating a good strong learner performance. By combining many of these weak learners, en...
Chapter
Analytical modeling is the key approach for a better understanding of the electromagnetic phenomena in electrical machines. Wave and permeance is one of the simple methods that is utilized frequently in electric machine modeling. The method is based on air gap magnetic field modeling, which consists of a stator and rotor magnetic field. The stator...
Chapter
One of the most important concerns in the manufacturing industry and in power plants is the prevention of unplanned stoppage of electric machines. Various methods have been used for condition assessment of synchronous machines, such as: an electromagnetic‐based approach based on various signal measurements; partial discharge measurement; vibration...
Chapter
This chapter investigates condition monitoring based on the vibration signals in synchronous generators. It presents general details about vibration in synchronous generators. The chapter explains the detailed analysis of the air gap magnetic field and forces that create vibration in the machine body in a healthy and faulty condition. Protective re...
Chapter
The synchronous generator is the most essential equipment in electrical energy generation. This chapter provides a history of the synchronous generator from the beginning until the present. All synchronous generators, including diesel, gas, and steam, are utilized in thermal power stations, large hydroelectric turbines in hydro‐power stations, and...
Chapter
This chapter presents the history of insulation of rotating electrical machines, different types of partial discharges (PDs), and PD measurement sensors. PD consists of small sparks that occur in electrical machine insulation. The methods used for the PD diagnosis in electrical machines can be divided into online and offline categories. The factors...
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Full-text available
Performance analysis of a linear permanent magnet Vernier machine (LPMVM), which has a complex structure, is mostly based on the finite element methods, while for its optimisation or sensitivity analysis a quick mathematical technique is desirable. This paper introduces an LPMVM and its principles of operation. Then, a mixed subdomain and magnetic...
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Permanent magnet (PM) machines have gained increasing attention from the industry because of their potential merits over conventional electrical machines. High‐temperature level in electrical machines is a major factor that can adversely impact the performance and health conditions of these machines. These effects need to be minimized to make them...
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Air-gap eccentricity fault causes rotor-stator rub and consequently damage to Synchronous Generators (SGs). In this paper, a fault diagnosis approach to diagnose the eccentricity fault for SGs is presented. In this approach, the state matrix eigenvalues based on the subspace identification are estimated, and those are used for fault diagnosis. Two...
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Full-text available
Abstract Flux‐based fault diagnosis methods have attracted ever‐increasing attention from technical communities because of their potential diagnostic capabilities and ability to overcome weaknesses of the traditional methods such as motor current signature analysis (MCSA). This study reviews recent literature on these methods and addresses their st...
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The cover image is based on the Review Article Airgap and stray magnetic flux monitoring techniques for fault diagnosis of electrical machines: An overview by Jawad Faiz et al., https://doi.org/10.1049/elp2.12157. image
Chapter
In order to reduce the global energy consumption, the energy efficiency must be improved. Electric motors are the major consumers of electrical energy and their efficiency improvement can have a very large impact on saving electrical energy. This chapter focuses on the latest advancements of various types of electric motors. These advancements spri...
Article
Any reduction in the cross-sectional area of wires (RCSAW) in the stator or rotor (field or damper) windings of synchronous generators (SGs) is considered as a fault in SGs. In this paper, a signal-model-based fault detection, isolation, and estimation approach based on the eigenvalues estimation of SGs is presented to diagnose RCSAW fault. The sub...
Article
The spoke-type arrangement of permanent-magnets (PMs) in rotor of Vernier-PM (VPM) machines was first introduced in a dual-stator topology to overcome low power drawback of VPM machines. However, this special structure is mostly applicable for high-power motor drives. This paper presents a fractional-slot spoke-array VPM machine with a special roto...
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Full-text available
In this paper, an online model-based fault detection approach based on residual analysis in synchronous generators (SGs) is presented. Two types of faults are studied in this paper: (i) reduction of the cross-sectional area of windings wires in SGs, and (ii) air-gap eccentricity. The residual vector based on the equivalent circuit (EC) parameters o...
Article
Stator and rotor structures, arrangement of permanent magnets (PMs), and type of coils of PM Vernier machines are reviewed and classified. Then, electromagnetic performance and the energy conversion process in the machine are described. Determination of magnetic field distribution and air-gap permeance of the machine is very complicated than that o...
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Full-text available
Abstract Operation of Vernier machines is based on flux modulation. They have some advantages including maintaining the rated torque in motor applications and the rated output power in generator applications at low speeds, high torque density and relatively low torque ripple due to their magnetic gear property and fault‐tolerance. In recent years,...
Article
The cover image is based on the Review Article Single stator-single rotor permanent magnet Vernier machine topologies for direct-drive applications: Review and case study by Jawad Faiz et al., https://doi.org/10.1002/2050-7038.13240.
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Special attention has been paid to two-phase switched reluctance motors (SRMs) as they have fewer power electronics components compared to three- or multi-phase ones. However, their main drawbacks are the lack of starting torque and a predetermined direction of rotation. This paper proposes a new self-starting technique for two-phase SRMs, which ha...
Article
This paper presents a method for estimating the equivalent circuit parameters of three-phase induction motors by employing the extended Kalman filter. In this method, the stator currents and voltages, and rotor speed of the motor under an unspecified load and in unsaturated condition are considered. The rotor resistance, mutual inductance, and stat...
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Abstract Thermal models are widely used for diagnosing thermal faults, predicting the thermal behaviour, estimating hot spots, and evaluating the loading capacity. This paper uses a new advanced thermal model, thermography method, and computational fluid dynamic separately to obtain the top‐oil and radiator temperatures. The model consists of four...
Article
Early detection of internal faults within the transformer reduces the outage and repair costs by planning the repair procedure according to the circumstances and prior to a catastrophic failure. Thermal faults are types of internal faults, which lead to high temperatures in the transformer causing accelerated aging of the insulation or its short-te...
Article
Armature reaction is considered as one of the challenging problems in on-load permanent magnet (PM) motors. Reducing the undesirable impacts of the armature reaction is necessary to improve the PM motors performance. The ironless stator PM motor is known as an appropriate choice for low armature reaction. Although in these motors, disturbing high-o...
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Full-text available
Abstract The authors analyse no‐load and full‐load performance of a permanent magnet transverse flux generators (PMTFGs) in fully aligned condition as well as under different types of mechanical faults including static eccentricity (SE), dynamic eccentricity (DE), inclined rotor (IR) and run‐out (RO) faults. An analytical model is developed to calc...
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Full-text available
Synchronous generator (SG) plays a vital and critical role in the power system by supplying electric power to consumers. Various faults in SGs can cause some catastrophic events such as power disruption or blackout. These faults can be classified into two electrical and mechanical faults. Short circuit in stator windings and field winding are elect...
Article
Eccentricity fault is a common fault in axial flux permanent magnet (PM) machines that can be destructive. The finite element method (FEM) has been already used for modelling eccentricity fault in disc type PM machine. Applying three-dimensional (3D) FEM to this motor is essential. However, 3D-FEM is a very time-consuming technique. Therefore, it i...
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Full-text available
The main idea of this paper is to offer a continuous C-cores unique configuration for switched reluctance motor (SRM) and to present an analytical model for its analysis. The proposed SRM is analyzed by finite element method (FEM) and by employing magnetic flux density pattern and magnetic fluxes path, its magnetic equivalent circuit (MEC) is obtai...
Article
Linear permanent magnet Vernier machines (LPMVMs) is an attractive solution for stroke and direct-drive applications. Several LPMVM topologies have been presented for different applications that operate based on magnetic flux modulation. LPMVMs have some advantages including high force, and torque density at low speeds. This paper introduces a doub...
Article
Although Vernier machines have been introduced a long ago, their description, applications, and design improvement have been recently proposed. This paper reviews different types of linear Vernier machine. Their description and theoretical base of the performance are presented. The performance of the motor is improved by reducing the cogging force,...
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Permanent magnet vernier generators (PMVGs) are suitable for meeting power concussion requirements of traffic enforcement cameras and traffic‐driven applications. In this study, the performance of PMVGs at no‐load and full‐load are analysed in healthy machines and machines under different types of mechanical faults including static eccentricity, dy...
Article
Ferroresonance leads to a high saturation of the transformer core. This causes severe rise of the amplitude of current and voltage of the transformer and leads to current and voltage non-sinusoidal waveforms. Therefore, the increase of the transformer losses and its temperature rises during Ferroresonance can overstress the transformer insulation s...
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Full-text available
Fault diagnosis of brush-less direct current (BLDC) motors has recently gained more attention. Inter-turn faults in BLDC motors distort three-phase currents waveform, leading to an asymmetrical condition. This paper introduces a simple and efficient method to identify inter-turn faults based on one modal current and four different simple indices. T...
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Thermal conditions of power transformers in abnormal operating conditions such as harmonic loads can be considered as a critical case. In this study, thermal analysis of transformer and additional imposed heat on it, caused by non‐linear loads, are addressed. For this purpose, an appropriate thermal equivalent circuit is used in which temperature o...
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Single‐sided linear induction motors (SLIMs) are used in maglev levitation systems for propelling purpose. The reasons for such usages are their capability in direct drive applications with very good dynamic performance, high reliability and high flexibility in trajectory generation. High‐performance requirements of the machine demand a high salien...
Article
Electric power transformer is a vital apparatus in power systems and failure prognostics is significant for the protection of this asset. In addition to the asset damage, its unexpected failure would interrupt power delivery and jeopardize the stability of the system. There are several fault diagnosis methods introduced for the detection of this ki...
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Full-text available
Condition monitoring is an essential technology for detecting various incipient defects in electrical machines. Stator inter‐turn and rotor broken bar faults are two major faults of the squirrel cage induction motors (SCIMs). Many attempts have been made to provide fault diagnosis systems for detecting the faults individually. This study proposes a...
Article
Rare-Earth Permanent Magnets (RE-PMs) are widely used in high efficiency and high torque density electrical machines. However, in recent years the exclusive and unstable supply of Rare-Earth Elements (REEs) is a major concern to substitute RE-based electrical machines by less or even no RE alternatives. Ferrite (Fe) PMs as the least expensive PMs s...
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Full-text available
Permanent magnet flux switching machines (FSPMs) have attracted considerable attention in recent years, due to their outstanding characteristics to operate as brushless AC drives. Since they are relatively new, there are particular challenges not only for their design procedure but also for their operating principle comprehension. This study highli...
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This paper presents surrogate-model based optimization for synchronous reluctance motor (SynRm) with transversally laminated rotor. A radial basis function (RBF) model with 12 input variables and three outputs is first trained. A dataset is obtained using finite element method to estimate parameters of RBF model. By building RBF model, the RBF netw...
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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 u...
Article
—To insure the health of power transformers insulation, its heat distribution in different operating conditions must be determined. In extended thermal equivalent circuits (TECs), less attention has been paid to losses and temperature distribution of different parts such as core, tank and metallic regions of transformer. Most previous works, hot-sp...
Article
Full-text available
Although interior permanent magnet brushless direct current (IPMBLDC) motors have higher torque and power density compared to surface‐mounted PMBLDC motors, the reluctance torque of IPMBLDC motors generates higher torque ripples. This study introduces a new current waveform as a reference to control the IPM motors while keeping the total developed...
Article
The frequency response analysis (FRA) is a promising diagnostic method for detecting mechanical faults inside a power transformer. Despite the standardization of the FRA measurement procedure, the interpretation of the results is still a subject of study. The reason lies in the fact that the frequency response is different from case to case. Theref...
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Full-text available
Eccentricity fault with 10% severity is probably the only existing fault in a brand new healthy electrical machine that is acceptable as a manufacturing tolerance. This fault can be developed due to a continuous pull between stator and rotor, even in a de-energized machine. So, it must be diagnosed,and its severity monitored. The authors introduced...
Article
The synchronous generator is one of the most expensive and important components of power systems. Therefore, it must be protected against any fault. To prevent fault expansion, appropriate protection must be able to quickly diagnose generator internal faults. Meanwhile, protection system security depends on the stability of power system transients....
Preprint
Full-text available
This paper introduces modelling magnetization characteristic of real ferromagnetic materials. Several equations are fitted to the actual magnetization characteristic. Then, they are employed in a magnetic equivalent circuit model and results verified with finite element method and a good agreement is achieved.
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There is always uncertainty in industrial manufacturing. These uncertainties have an undesirable impact on the products if deterministic optimization approaches are employed. In order to have products as desired, uncertainties must be quantified in the design process. This paper presents a robust design optimization of an outer rotor surface mounte...
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Full-text available
Deformation of the windings is one of the main causes of the power transformers failure. Here, for the first time, the electromagnetic forces exerted on the windings are computed in ferroresonance condition and compared with that of the inrush current for a typical power transformer. In both cases, the magnetic core of the transformer saturates and...