Original Article
Modeling, analysis and design of electromechanical systems
Hamed Tahanian; Ahmad Darabi
Abstract
Magnetic hysteresis affects the performance of electromagnetic devices, e.g., motors, generators, and transformers. However, due to complex, non-linear, and multi-valued nature of this phenomenon, its accurate coupling to Finite Element Analysis (FEA) of these devices has been always a challenging task. ...
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Magnetic hysteresis affects the performance of electromagnetic devices, e.g., motors, generators, and transformers. However, due to complex, non-linear, and multi-valued nature of this phenomenon, its accurate coupling to Finite Element Analysis (FEA) of these devices has been always a challenging task. A novel approach has been presented in this paper for linking FEA to the Preisach model, which is known as the most accurate hysteresis model. An individual Preisach module has been considered for each field component of each element of the hysteresis material mesh. Hysteresis characteristics between each two successive time steps have been linearly approximated. An iterative algorithm has been proposed for obtaining field distributions along with parameters of these lines, simultaneously. The proposed method has been applied to a general magnetic circuit to predict its behavior over a given time span. Space distributions of flux density at some time steps, time variations of flux density and field intensity for one element, induced voltage, and hysteresis characteristics for some elements have been obtained. In contrast with most previous works, approach of this paper could reflect the details of hysteresis phenomenon, including minor loops, into the FEA. Also, it is applicable to problems with non-uniform and rotating field distributions.
Review Article
Modeling, analysis and design of electromechanical systems
Mehdi Aliahmadi; Alireza Ghaempanah; Javad Faiz
Abstract
Increasing loading without comparable change in the size of synchronous generators, causes end-winding force estimation become important. Therefore, design of an appropriate support to protect windings deterioration and damages by the above mentioned forces is critical. In slot-embedded portion of coils, ...
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Increasing loading without comparable change in the size of synchronous generators, causes end-winding force estimation become important. Therefore, design of an appropriate support to protect windings deterioration and damages by the above mentioned forces is critical. In slot-embedded portion of coils, the forces could be adjusted by teeth and slot wedges. Normally, the ends of coils have no external support and it is necessary to provide it. Synchronous generators have been considered reliable if accurate end winding forces are evaluated and taken into account in the design process of the external support. The topic based on the current literature is reviewed. Structure of end windings and different analytical and numerical techniques for forces estimation are discussed. The current state of the art is reviewed and more successful developments are introduced. At the end, the area of research which needs more attention in the future to advance the subject is identified.
Original Article
Modeling, analysis and design of electromechanical systems
Alireza Sheikhi Fini
Abstract
Iran is one of the known countries that has unfavorable energy efficiency, therefore the policy makers of the country have put the correction of this situation on the agenda. This paper has been compiled to review and study the basics of the road map for the development of high-efficiency building technologies ...
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Iran is one of the known countries that has unfavorable energy efficiency, therefore the policy makers of the country have put the correction of this situation on the agenda. This paper has been compiled to review and study the basics of the road map for the development of high-efficiency building technologies and to present a picture of the current state of these technologies in the country. In this paper, the necessity and importance of these technologies and the necessity of developing a road map for this development are expressed. Gathering all the upstream documents in the field of these technologies, the current state of the technology and its characteristics, actors and stakeholders are examined. The strengths and weaknesses in the country for the development of energy-efficient technologies in the building sector have been identified, then the threats and opportunities caused by external factors (outside the country), which stand in the way of the development of energy-efficient technologies in the building sector inside the country, has been studied. A drawing of the existing situation is also provided. This article is useful and effective for policymakers and planners, managers and officials, researchers and academics, industrialists and builders, and in other words, all stakeholders in the field of electricity industry.
Original Article
Control of Electromechanical systems
mohammadmahdi kazemi; alireza rezazade
Abstract
In this paper, two different structures of a multiphase inverter for controlling a Brushless DC (BLDC) motor are presented and compared parameters These two structures are in fault mode. In the first structure, each phase of the BLDC motor is fed from an individual H-Bridge inverter, which is controlled ...
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In this paper, two different structures of a multiphase inverter for controlling a Brushless DC (BLDC) motor are presented and compared parameters These two structures are in fault mode. In the first structure, each phase of the BLDC motor is fed from an individual H-Bridge inverter, which is controlled by a Proportional-Resonance (PR) controller. The system dealt with in this paper is designed especially for reliability-critical applications. In other words, the motor structure has to be implemented not to compromise the drive performance even in fault conditions. For these purposes, modular designs to minimize the coupling between each phase. in the second structure, a typical six-legged inverter is used, which is divided into two groups of three phases with double Y-connected windings displaced by 30 degrees is presented and switching is done using Space Vector Pulse Width Modulation (SVPWM). According to the model, the use of SVPWM modulation for a six-phase motor reduces computations. MATLAB/Simulink software has been used to analyze these two structures and the results of its simulations are given.
Original Article
Condition monitoring and fault diagnosis
Alireza Sheikhi Fini; Ahmad Esmaieli; Mehdi Karimian; Hosein Borhani; Mehdi Moallem
Abstract
Due to the increasing non-linear loads in power systems and furthermore, the increase of loads sensitive to power quality pollution, power quality issues have become important. Power quality disturbances in general cause many problems for power systems. One of the most important problems is economic ...
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Due to the increasing non-linear loads in power systems and furthermore, the increase of loads sensitive to power quality pollution, power quality issues have become important. Power quality disturbances in general cause many problems for power systems. One of the most important problems is economic issues and costs imposed on the network. In this paper, the classification of the origin of power quality problems and the most important technical damages caused by power quality are addressed. Therefore, in this article the effect and distortions of power quality on losses and lives of equipment i.e. cables and overhead lines, power transformers, capacitor banks are formulated. Furthermore, the costs and damages caused by these disturbances on various equipment of power system have been investigated. In this regard, using the results of power quality measurement in Khizrabad (Yazd) Industrial Substation, the amount of damage to the system has been calculated in this pilot.
Review Article
Magnetic, Electric and insulation materials
Banafsheh Mirtaheri; Hamed Tahanian
Abstract
Permanent Magnets (PMs) are employed in many modern devices, thanks to their unique properties. Electrical machines, i.e., motors and generators, are a major application of PMs, which produce the required magnetic field. When there are severe constraints on the weight and dimensions of the device (e.g. ...
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Permanent Magnets (PMs) are employed in many modern devices, thanks to their unique properties. Electrical machines, i.e., motors and generators, are a major application of PMs, which produce the required magnetic field. When there are severe constraints on the weight and dimensions of the device (e.g. in hybrid electric vehicles or wind turbines), using high-energy PMs would be of crucial importance. Currently, PMs which contain Rare-Earth Elements (REEs), e.g. Sm-Co and Nd-Fe-B, are the most commonly used and the most powerful practical PMs. However, the monopolized supply of the raw materials required for the production of these PMs as well as the recent rise in their global price, have encouraged researchers to investigate some methods for reducing the consumption of REEs or substituting other PMs for those with REEs. This paper studies the state of the art advances in developing PMs with less or no REEs and the corresponding achievements.
