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inductance
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The principle of open induction and specker sequences
, Article Logic Journal of the IGPL ; Volume 25, Issue 2 , 2017 , Pages 232-238 ; 13670751 (ISSN) ; Ghafouri, Z ; Sharif University of Technology
Oxford University Press
2017
Abstract
The schema ED asserts that 'there exists an intuitionistically enumerable subset of N which is not intuitionistically decidable.' In this article, we prove that in the presence of Markov's Principle over Bishop's constructive analysis, ¬ED is equivalent to the principle of open induction on [0,1], via Specker sequences. © 2016. Oxford University Press. All rights reserved
A control strategy for reducing the torque ripple in low speed operation of direct torque controlled induction motor
, Article 2004 IEEE International Symposium on Industrial Electronics, IEEE-ISlE, 4 May 2004 through 7 May 2004 ; Volume 2 , 2004 , Pages 1203-1208 ; Zolghadri, S. M. R ; Haghbin, T. S ; Homaifar, F. A ; Sharif University of Technology
2004
Abstract
A new switching table is proposed for decreasing the torque ripple in DTC especially in low speed. Each sector is divided to two half sector and a proper vector set is defined for each. Through this new switching table, the torque response is smooth even in the beginning of each sector and it leads to the reduction of torque ripple. None of motor parameters are used in this switching strategy and there is no need to shorten the sampling period. Simulation and experimental results confirm the ability of this method in reducing the torque ripple. ©2004 IEEE
Torque ripple minimization in DTC of induction motor based on optimized flux value determination
, Article The 29th Annual Conference of the IEEE Industrial Electronics Society, Roanoke, VA, 2 November 2003 through 6 November 2003 ; Volume 1 , 2003 , Pages 431-435 ; Zolghadri, M. R ; Haghbin, S ; Emadi, A ; Sharif University of Technology
2003
Abstract
Torque ripple is a major difficulty in direct torque controlled induction motors. The reference value of the motor flux greatly influences the torque ripple. On the other hand, many motors work in an operating cycle, which includes load intervals of less than their nominal power. In these situations, it is not necessary to set their flux value as the nominal value. In this paper, the effect of the reference value of the motor flux on the motor torque ripple is investigated. A new control algorithm is proposed to determine the reference value of the flux according to the value of the motor torque. Simulation and experimental results justify the validity of the proposed method to reduce the...
A criterion to evaluate the accuracy of reduced order models of induction generators based on neglecting stator transients
, Article 5th IFAC Symposium on Power Plants and Power Systems Control 2003, 15 September 2003 through 19 September 2003 ; Volume 36, Issue 20 , 2003 , Pages 509-512 ; 14746670 (ISSN) ; Varahram, M. H ; Sharif University of Technology
IFAC Secretariat
2003
Abstract
Various attempts has been made to derive linearized, reduced order models of induction generators. Due to the fact that there is usually numerous number of these machines in wind power plants, these models provide great facilities in calculations, and therefore are used widely in power system transient stability studies.Among various order reduction methods the most applicable ones are those based on neglecting the stator transients of the machine.In this paper, some of these methods are discussed and a criterion has been introduced to evaluate the accuracy of resultant reduced order models. Copyright © 2003 IFAC
Effects of the flux value on the torque ripple of the direct torque controlled induction motor drives determination
, Article 5th International Conference on Power Electronics and Drive Systems, PEDS 2003, 17 November 2003 through 20 November 2003 ; Volume 1 , 2003 , Pages 439-444 ; 0780378857 (ISBN) ; Zolghadri, M. R ; Haghbin, S ; Homaifar, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2003
Abstract
Torque ripple is a major difficulty in direct torque control of induction motors. The reference value of the motor flux greatly influences the torque ripple. On the other hand, many motors work in an operating cycle, which includes load intervals of less than their nominal power. In these situations, it is not necessary to set their flux value as the nominal value. In this paper, the effect of the reference value of the motor flux on the motor torque ripple is investigated. The effect of the flux reference variation on the motor power factor as well as torque dynamics is also presented. Simulation results as well as experimental results justify the validity of the proposed method on the...
Low voltage ride-through of DFIG and brushless DFIG: Similarities and differences
, Article Electric Power Systems Research ; Vol. 110 , May , 2014 , p. 64-72 ; ISSN: 03787796 ; Tavner, P ; McMahon, R ; Oraee, H ; Zolghadri, M. R ; Shao, S ; Abdi, E ; Sharif University of Technology
Abstract
The brushless doubly fed induction generator (BDFIG) has been proposed as a viable alternative in wind turbines to the commonly used doubly fed induction generator (DFIG). The BDFIG retains the benefits of the DFIG, i.e. variable speed operation with a partially rated converter, but without the use of brush gear and slip rings, thereby conferring enhanced reliability. As low voltage ride-through (LVRT) performance of the DFIG-based wind turbine is well understood, this paper aims to analyze LVRT behavior of the BDFIG-based wind turbine in a similar way. In order to achieve this goal, the equivalence between their two-axis model parameters is investigated. The variation of flux linkages,...
A survey on rotor faults in brushless doubly fed machines
, Article Proceedings of the 2011 3rd International Youth Conference on Energetics, IYCE 2011, 7 July 2011 through 9 July 2011 ; July , 2011 , Page(s): 1 - 8 ; 9781457714948 (ISBN) ; Gorginpour, H ; Saket, M. A ; Oraee, A ; Ahmadian, M ; Oraee, H ; Sharif University of Technology
2011
Abstract
The cause of about 10% of faults in induction machines is related to the rotor part. In this paper, an analytical method for general modeling of brushless doubly-fed machines (BDFMs) with broken rotor loops and end ring is presented. The approach is based on calculation of resistance and inductance matrices through the winding function of the machine, so the assumption of sinusoidal MMF is not needed. It is also shown that a fault in a loop can lead to faults in other parts of the rotor. To validate the method a simulation in MATLAB/Simulink is performed based on the D180-frame prototype BDFM
A novel torque hysteresis comparator for torque and current ripple reduction of direct torque control of induction machine
, Article 9th IEEE International Power Electronics Congress, CIEP 2004, Celaya, Gto, 17 October 2004 through 22 October 2004 ; 2004 , Pages 140-145 ; Zolghadri, M. R ; Haghbin, S ; Sharif University of Technology
2004
Abstract
The notable effeets of time delay aid time discretization on the torque and current ripple amplitude of the direct torque controlled induction motor scheme are investigated. A simply modified torque hysteresis comparator structure is proposed. It minimizes the undesirable effects of the time delay and time discretization on the torque ripple and allows a sensible reduction of torque and current ripple amplitudes and switching frequency in the whole rotor speed range. Numerical simulations and experimental tests have been carried out to validate the proposed torque comparator effect. © 2004 IEEE
Online optimal flux controller for DTC based induction motor drives
, Article IECON 2004 - 30th Annual Conference of IEEE Industrial Electronics Society, Busan, 2 November 2004 through 6 November 2004 ; Volume 2 , 2004 , Pages 1391-1395 ; Zolghadri, M. R ; Roye, D ; Emadi, A ; Sharif University of Technology
2004
Abstract
A flux search controller is proposed to achieve the best efficiency in a direct torque controlled induction motor with light load. The reference flux value is determined through a minimization algorithm with stator current as objective function. Experimental results show that using motor current instead of motor input power as the objective function causes better performance. © 2004 IEEE
Effects of sampling time on the performance of direct torque controlled induction motor drive
, Article IEEE International Symposium on Industrial Electronics, ISIE 2003, 9 June 2003 through 11 June 2003 ; Volume II , 2003 , Pages 1049-1052 ; 0780379128 (ISBN) ; Zolghadri, M. R ; Homaifar, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2003
Abstract
The torque ripple and harmonic loss of motor and switching loss of inverter are greatly influenced by sampling time in the direct torque control method. Hence these variables must be observed in the control process to maximize performance of the system. In this paper the effects of sampling time on inverter switching loss, harmonic loss and torque ripple of induction motor are investigated. To find their optimum values a cost function consisting of motor harmonic losses, torque ripples and inverter switching losses are defined. Minimizing this cost function leads to the optimum value of the sampling time. © 2003 IEEE
A Critical Review of the Argument Called “Unconceived Alternatives”
, M.Sc. Thesis Sharif University of Technology ; Taqavi, Mostafa (Supervisor)
Abstract
Scientific realism has always faced continuous criticism from anti-realists. Kyle Stanford's argument based on the problem of "unconceived alternatives" can be seen as a late and troublesome version of these challenges. In this thesis, first in the first chapter, after explaining the main points of conflict in the scientific realism/anti-realism debate, we will list the main positions in these two camps, and then we will mention the arguments in favor of scientific realism. After that, we will list the main challenges that scientific realism has faced. Arguments such as pessimistic meta-induction and underdetermination which are raised against scientific realism. In the second chapter, we...
Crosstalk stability analysis in multilayer graphene nanoribbon interconnects
, Article Circuits, Systems, and Signal Processing ; Volume 32, Issue 6 , 2013 , Pages 2653-2666 ; 0278081X (ISSN) ; Faez, R ; Sharif University of Technology
2013
Abstract
In this paper a time-domain response and Nyquist stability criterion to acquire dependence of degree of crosstalk relative stability based on transmission lines modeling (TLM) is investigated for coupled multilayer graphene nanoribbon (MLGNR) interconnects. This is the first instance that such an analysis has been presented for coupled MLGNR consisting of both capacitive and mutual-inductive couplings. The near-end and far-end outputs of coupled MLGNR individually are compared in two cases, with considering both couplings and without them (single MLGNR). It is observed that the near-end output of the system together with both couplings is more stable and at its far-end output, an induced...
Performance analysis of outer-rotor single-phase induction motor based on magnetic equivalent circuit
, Article IEEE Transactions on Industrial Electronics ; Volume 68, Issue 2 , 2021 , Pages 1046-1054 ; 02780046 (ISSN) ; Nasiri Gheidari, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Single-phase, outer-rotor squirrel cage induction motors are widely used in ceiling fan applications. Furthermore, they can be employed for pumps, and in-wheel hub drives. In this article, an analytical model based on magnetic equivalent circuit is proposed to evaluate the performance of the motor. The influence of rotor slots' skewing, stator end windings, slots' leakage inductance, and core saturation are included in the model. Furthermore, the windings' copper losses and the core's iron losses are calculated using the proposed model. The results of the presented model are compared with those of time variant finite element analysis (TVFEA) and experimental measurements close agreement...
True Class-E Design For Inductive Coupling Wireless Power Transfer Applications
, Article 30th International Conference on Electrical Engineering, ICEE 2022, 17 May 2022 through 19 May 2022 ; 2022 , Pages 864-868 ; 9781665480871 (ISBN) ; Safarian, A ; Fotowat Ahmady, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
The Class-E power amplifier has been widely studied and formulated in the literature. Although the majority of reported inductive coupling wireless power transfer (WPT) systems use a class-E power amplifier for driving the primary coil, still there is a lack of a comprehensive study on class-E circuit dedicated to WPT, providing a set of closed form design equations for proper class-E operation. This paper presents the required design equations needed to design a 'true' class-E circuit for WPT applications. Equations for the series-tuned secondary coil WPT system are presented, as well as two different design procedures for the parallel-tuned secondary coil. The derived equations have been...
The Making of Vacuum Induction Melting Furnace and the Survey of the Influences of Temperature and Material of Crucible on Created Type of Inclusion in Super Alloyed Based Nickel IN738LC
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
The purpose of this project is to survey the created kind of inclusion in super alloyed based nickel. primarily, for this matter for the preparing of super alloyed based nickel, the vacuum induction melting furnace has been designed and built , then for surveying the kind of inclusion the effective parameters such as temperature , timing and material of crucible has been considered accordingly , the material of crucibles was considered based on mud-clay- graphitic- pure graphitic- aluminum- zirconium. From the obtained analysis samples of SEM has been distinguished which, with increasing of the temperature and the time ,the percentage of impurity will go up in super- alloyed and the...
Study of Melting Process of Dri, Product of Tunnel Kiln, in Induction Furnace
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
Due to the expanding trend of using induction furnaces in Iran, the production of sponge iron at a smaller scale by Midrex method has become important. Since induction furnaces cannot benefit from the oxygen blower and foam slag like arc furnaces, the induction furnace charge should be of a higher quality. In addition, as the oxidation conditions in induction furnace are higher in comparison to arc furnaces, re-oxidation control of the induction furnace is essential. Making briquettes is one of the processes, which reduces re-oxidation during melting and since the briquette remains floated on the melt until complete melting, the lower level of briquette's contact with ambient atmosphere and...
Magnetic equivalent circuit modelling of brushless doubly-fed induction generator
, Article IET Renewable Power Generation ; Vol. 8, Issue. 3 , 2014 , pp. 334-346 ; ISSN: 1752-1416 ; Jandaghi, B ; Oraee, H ; Abdi, E ; Sharif University of Technology
Abstract
The brushless doubly-fed induction generator (BDFIG) has substantial benefits, which make it an attractive alternative as a wind turbine generator. The aim of this work is to present a nodal-based magnetic equivalent circuit (MEC) model of the BDFIG which provides performance characteristics and flux density distributions. The model takes into account stator winding distributions, special configuration of rotor bars, slotting effects, teeth saturation, flux fringing and current displacement effects. The real flux tubes are considered for creating an MEC network and calculating its non-linear elements. A method for simplifying the rotor magnetic network has been applied and Gauss elimination...
Statistical study of nano-scale VLSI interconnect crosstalk and its induced power estimation
, Article 2012 2nd IEEE CPMT Symposium Japan, ICSJ 2012, 10 December 2012 through 12 December 2012 ; December , 2012 ; 9781467326551 (ISBN) ; Sarvari, R ; Seyedolhosseini, A ; Sharif University of Technology
2012
Abstract
Crosstalk due to the capacitive and inductive coupling has adverse effect on the circuit performance. In this paper crosstalk voltage and its induced power are studied for a stochastic environment bus with specific physical structure. Input switching pattern, driver, and load are swept in wide range for VLSI application to study crosstalk variation. Crosstalk and power is extracted to drive mean and standard deviation for implemented structures. The crosstalk mean and its induced power get lower with increasing of the load and driver resistance. This phenomenon is proportional to shrinking the technology
Dynamic model for Brushless Doubly-Fed Machine with stator winding faults
, Article PEDSTC 2010 - 1st Power Electronics and Drive Systems and Technologies Conference, 17 February 2010 through 18 February 2010 ; February , 2010 , Pages 316-322 ; 9781424459728 (ISBN) ; Sotoodeh, P ; Oraee, H ; Sharif University of Technology
2010
Abstract
In this paper, a detailed analytical model for dynamic analysis of the Brushless Doubly-Fed Machine is presented. The model is capable to predict the machine behavior under different modes of operation including: simple induction mode, cascade mode and synchronous mode, both with and without winding faults and unbalanced excitations. The proposed approach employs the basic principles of the generalized harmonic theory for calculating self inductances and mutual inductances of circuits with any distribution of conductors. Dynamic equations of modified coupled-circuit method are then solved to compute the currents flowing in the stator windings and rotor loops
Measurements of the plasma current density and q-profiles in IR-T1 tokamak
, Article Journal of Fusion Energy ; Volume 29, Issue 3 , June , 2010 , Pages 232-236 ; 01640313 (ISSN) ; Salar Elahi, A ; Abbaspour Tehrani Fard, A ; Tajdidzadeh, M ; Sharif University of Technology
2010
Abstract
The purposes of this paper are determination of the current density and safety factor profiles, J(r) and q(r), in IR-T1 tokamak. For these purposes, a diamagnetic loop with its compensation coil, and also an array of magnetic probes were designed, constructed, and installed on outer surface of the IR-T1 tokamak chamber, and then the poloidal beta and poloidal and radial magnetic fields measured. Moreover, a few approximate values of the internal inductance for the different possible profiles of the plasma current density are also calculated. From the results, current density and q-profiles obtained