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Total 29 records

    A fast flux search controller for DTC based induction motor drives

    , Article PESC Record - IEEE Annual Power Electronics Specialists Conference ; Volume 2005 , 2005 , Pages 739-744 ; 02759306 (ISSN); 0780390334 (ISBN); 9780780390331 (ISBN) Kaboli, S ; Zolghadri, M. R ; Emadi, A ; Sharif University of Technology
    2005
    Abstract
    In this paper, a flux search controller is proposed to increase the efficiency of a direct torque controlled induction motor with light load. The reference flux value is determined through a two stage minimization algorithm with the amplitude of the stator current as the objective function. In the transient state, a great flux step is used to speed up the convergence. In the steady state, a noise cancellation algorithm is used to let using small flux step and improves the steady state behavior of flux controller. Simulation and experimental confirm the fast dynamics of the proposed method and its superiority compared to the other optimal flux search controllers. © 2005 IEEE  

    A new approach for the reliability-based robust design optimization of mechanical systems under the uncertain conditions

    , Article SAE Technical Papers, 10 April 2018 through 12 April 2018 ; Volume 2018-April , 2018 ; 01487191 (ISSN) Khodaygan, S ; Sharafi, M. H ; Sharif University of Technology
    SAE International  2018
    Abstract
    A mechanical system inherently affected by the conditions, factors, and parameters of uncertainties. Without including the uncertainty effects in the design procedure, the designs may not be robust and reliable. Robust design optimization (RDO) method is a procedure to find the insensitive design with respect to the variations. On the other hand, reliability is measured by the probability of satisfying a specific design criterion. Therefore, a reliable design is a design that satisfies the specified criteria even with some uncertainties in variables and parameters. Reliability-based design optimization (RBDO) is an optimization procedure that incorporates reliability requirements to find the... 

    A diversity based reconfigurable method for fault tolerant control of induction motors

    , Article International Symposium on Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006, Taormina, 23 May 2006 through 26 May 2006 ; Volume 2006 , 2006 , Pages 66-71 ; 1424401941 (ISBN); 9781424401949 (ISBN) Tahami, F ; Shojaei, A ; Ahmadi Khatir, D ; Sharif University of Technology
    2006
    Abstract
    AC motor drive systems are sensitive to faults occurring at the power inverter, or at the control system. A novel fault tolerant Field Oriented Control system for induction motors is introduced. The system maintains speed control in the event of sensors malfunction and adverse signal conditions, providing enhanced reliability. The system comprises four different flux estimators which are fused by a Fuzzy aggregation system in order to give a reliable estimate of motor flux. The proposed control system is an effective and easy to implement method giving a potential for motor drive reliability enhancement. © 2006 IEEE  

    On the performance of optimal flux search controller for DTC based induction motor drives

    , Article 2005 IEEE International Conference on Electric Machines and Drives, San Antonio, TX, 15 May 2005 through 15 May 2005 ; 2005 , Pages 1752-1756 ; 0780389875 (ISBN); 9780780389878 (ISBN) Kaboli, S ; Vahdati Khajeh, E ; Zolghadri, M. R ; Homaifar, A ; Sharif University of Technology
    IEEE Computer Society  2005
    Abstract
    Application of a flux search controller in direct torque control of induction motor drives produces divergence problem and steady state flux ripple, because of the disturbance in the control loop. In this paper, an investigation about the origin of this noise has been performed. It is shown that the variation of voltage harmonics is the main reason of disturbance in the flux control loop. The minimum allowable value of flux step has been determined based on this analysis to prevent the divergence problem. Feasibility of noise cancellation has been discussed. Experimental results are presented to justify the theoretical analysis. © 2005 IEEE  

    A fast optimal flux search controller with improved steady state behavior for DTC based induction motor drives

    , Article 2005 IEEE International Conference on Electric Machines and Drives, San Antonio, TX, 15 May 2005 through 15 May 2005 ; 2005 , Pages 1732-1736 ; 0780389875 (ISBN); 9780780389878 (ISBN) Kaboli, S ; Vahdati Khajeh, E ; Zolghadri, M. R ; Homaifar, A ; Sharif University of Technology
    IEEE Computer Society  2005
    Abstract
    Flux search controllers are proposed to improve the efficiency of electrical motors especially induction motors. In this paper, a flux search controller is proposed to increase the efficiency of a direct torque controlled induction motor with light load. The reference flux value is determined through a two stage minimization algorithm with the amplitude of the stator current as the objective function. In the transient state, a great flux step is used to speed up the convergence. In the steady state, a noise cancellation algorithm is used to let using small flux step and improves the steady state behavior of flux controller. Simulation and experimental confirm the fast dynamics of the... 

    A novel double carrier PWM modulation for sensorless control of permanent magnet synchronous motors

    , Article 10th International Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2019, 12 February 2019 through 14 February 2019 ; 2019 , Pages 127-131 ; 9781538692547 (ISBN) Hosseinyar, H ; Karimi, S ; Tahami, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Control of Synchronous Motors at low speed has been the topic of several studies for the last years. Due to the lower amplitude of Back-EMF voltage in lower speed, it is inappropriate to merely rely on induced voltages for position estimation. In this paper, a new double carrier PWM modulation is presented in which two carrier frequencies are utilized for two legs of the inverter. This proposed method rectify the need of powerful processors which decreases the cost of the electric drive system. Employing a non-linear control system and an automatic gain control, ensures the sensorless control of the motor for a wide range of speed. © 2019 IEEE  

    Markov model of drive-motor systems for reliability calculation

    , Article International Symposium on Industrial Electronics 2006, ISIE 2006, Montreal, QC, 9 July 2006 through 13 July 2006 ; Volume 3 , 2006 , Pages 2286-2291 ; 1424404975 (ISBN); 9781424404971 (ISBN) Molaei, M ; Oraee, H ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2006
    Abstract
    Due to considerable use of electric drives in industrial applications, reliability assessment of drive-motor systems both in design and operating phases is of considerable importance. Reliability assessment of drive-motor systems is presented in this paper. Using the basic component of a drivemotor system, a suitable reliability block diagram is first developed. The system availability and reliability is then determined using developed block diagram. The impacts on system reliability of various parameters such as failure rate and repair rate of system components are investigated. The proposed technique is then applied to a practical drive-motor system and the results are presented. © 2006... 

    Functional process capability analysis in mechanical systems

    , Article International Journal of Advanced Manufacturing Technology ; Vol. 73, issue. 5-8 , July , 2014 , p. 899-912 ; 02683768 Khodaygan, S ; Movahhedy, M. R ; Sharif University of Technology
    Abstract
    Functional quality in the mechanical products is governed mainly by the degree of satisfaction of the design requirements, which itself depends on the variations in the effective variables. The functional parameters cannot be easily measured in mass production, and thus, are not usually considered as a direct inspection objective. Process capability indices are useful tools for evaluating the ability of a process to produce the dependent variables of a product that meet certain specifications. In this paper, the conventional process capability concept is extended to develop a computational tool for analysis of the functional quality of a mechanical product. Through defining new proper... 

    Speed control of servo drives with a flexible couplings using fractional order state feedback

    , Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2014 , p. 25-30 Tahami, F ; Moghadam, B. E ; Sharif University of Technology
    Abstract
    Using elastic couplings in servo motor drives may lead to torsional oscillations which are usually extinguished by reducing the bandwidth of the control system as a countermeasure. A high performance servo drive however needs fast dynamic characteristics. The conventional controllers, such as PI controllers, may not be able to improve the dynamic response while keeping the system stable. Fractional order modeling offers a good framework for flexible structures such as two mass servo drives. In this paper, the dynamic response and stability of two-mass servo drive is improved using a fractional order controller. The fractional order controller allows increasing the phase margin of the system... 

    Comparing different rotor structures in superconducting synchronous motors

    , Article Proceedings of the 2013 IEEE International Electric Machines and Drives Conference ; May , 2013 , Pages 1053-1057 ; 9781467349758 (ISBN) Elhaminia, P ; Yaghoobi, J ; Yazdanian, M ; Zolghadri, M. R ; Ferdowsi, M ; Sharif University of Technology
    2013
    Abstract
    Two major structures for rotor core of superconducting synchronous machine are air-cored and magnetic-cored structures. Magnetic-cored structure can be divided into two categories including salient and non-salient magnetic core. In this paper, three different structures of superconducting synchronous machine comprising air-cored, non-salient magnetic-cored and salient magnetic-cored, have been studied and compared considering required superconducting wire and machine weight. Required superconducting wire determines the capital cost and the weight of the machine determines the running cost in the case of portable applications such as ships and aircrafts  

    Comparison of efficiency for different switching tables in six-phase induction motor DTC drive

    , Article Journal of Power Electronics ; Volume 12, Issue 1 , 2012 , Pages 128-135 ; 15982092 (ISSN) Taheri, A ; Rahmati, A ; Kaboli, S ; Sharif University of Technology
    2012
    Abstract
    In this paper, different switching tables proposed for the Direct Torque Controlled (DTC) of a six-phase induction machine are simulated and implemented. A six-phase induction motor has 64 space voltage vectors which result in increased complexity in the selecting of inverters switching. The unsuitable selection of a switching table leads to large harmonics especially at low speed and it also reduces drive efficiency. A six-phase induction machine has large zero sequence harmonic currents of the order 6k ±1. These harmonic currents are varied in various techniques. Decreasing this loss is essential in a six-phase induction machine. The main purpose of this paper is to improve the ST-DTC of... 

    Implementation and hardware in the loop verification of five-leg converter control system on a FPGA

    , Article IECON Proceedings (Industrial Electronics Conference), 7 November 2011 through 10 November 2011, Melbourne, VIC ; 2011 , Pages 4015-4020 ; 9781612849720 (ISBN) Shahbazi, M ; Zolghadri, M. R ; Poure, P ; Saadate, S ; Sharif University of Technology
    2011
    Abstract
    FPGAs are interesting choices for control of power electronics converters and electrical drives. In this paper, implementation of the control method of a reduced switch- count five-leg converter is carried out. Two PWM methods are studied. For verification of the implemented controller in a practical manner, without risking the damaging of the real system, "FPGA in the loop" experiments are performed. It is shown that using the proposed methodology, FPGA implementation and verification is fast and effective. The provided results show the high performance of the implemented controller on the FPGA, therefore the feasibility and suitability of the FPGA for this application is approved  

    Modeling and control of a grid-connected BDFM under unbalanced grid voltage conditions

    , Article 2011 IEEE International Electric Machines and Drives Conference, IEMDC 2011, 15 May 2011 through 18 May 2011 ; May , 2011 , Pages 1647-1651 ; 9781457700613 (ISBN) Sotoodeh, P ; Seyed Mahdi Izadkhast ; Khosravi, H ; Oraee, H ; Sharif University of Technology
    2011
    Abstract
    This paper presents a mathematical model for Brushless Doubly-Fed Machine (BDFM) based on Stator Flux Orientation (SFO) in positive and negative reference frames under unbalanced grid voltage conditions. A negative controller is designed to eliminate the effects of unbalanced conditions on electrical torque. The model and controller performance during unbalanced conditions is validated by time domain simulation in MATLAB/Simulink  

    Modeling and optimization of an elliptical shape ultrasonic motor using combination of finite element method and design of experiments

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010, Vancouver, BC ; Volume 8, Issue PARTS A AND B , 2010 , Pages 491-496 ; 9780791844458 (ISBN) Sanikhani, H ; Akbari, J ; Shahidi, A. R ; Darki, A. A ; Sharif University of Technology
    2010
    Abstract
    Standing-wave ultrasonic motors are a modern class of positioning systems, which are used to deliver a high precision linear or rotary motion with an unlimited stroke. The design process should be performed through an effective optimization algorithm in order to guaranty proper and efficient function of these motors. An optimization method of ultrasonic motors is proposed based on the combination of finite element method and factorial design as a design of experiments in this study. The results show the ability of this method in optimal design of ultrasonic motors especially those which have a complex structure and multi modes operation principle  

    Probabilistic voltage harmonic analysis of direct torque controlled induction motor drives

    , Article IEEE Transactions on Power Electronics ; Volume 21, Issue 4 , 2006 , Pages 1041-1052 ; 08858993 (ISSN) Kaboli, S ; Vahdati Khajeh, E ; Zolghadri, M. R ; Sharif University of Technology
    2006
    Abstract
    In high frequency motor-drives such as direct torque controlled (DTC) induction motor drives, the motor harmonic loss, and electromagnetic interference are largely affected by the spectrum of the motor input voltage. Nonlinear elements in the control loop of DTC drive make harmonic analysis of the drive very complex compared to classical pulsewidth modulated controlled drives. In this paper, a probabilistic method to study the harmonic contents of voltage in DTC of induction motors is presented. The DTC voltage chain is simulated with a random process. Then, the autocorrelation function of voltage vectors is calculated and its power spectrum density is obtained. The effect of flux and torque... 

    Fault-tolerant five-leg converter topology with FPGA-Based reconfigurable control

    , Article IEEE Transactions on Industrial Electronics ; Volume 60, Issue 6 , 2013 , Pages 2284-2294 ; 02780046 (ISSN) Shahbazi, M ; Poure, P ; Saadate, S ; Zolghadri, M. R ; Sharif University of Technology
    2013
    Abstract
    Fast fault detection and reconfiguration of power converters is necessary in electrical drives to prevent further damage and to make the continuity of service possible. On the other hand, component minimized converters may provide the benefits of higher reliability and less volume and cost. In this paper, a new fault-tolerant converter topology is studied. This converter has five legs before the fault occurrence, and after fault detection the converter continues to function with four legs. A very fast fault detection and reconfiguration scheme is presented and studied. Simulations and experimental tests are performed to evaluate the structure requirements, the digital reconfigurable... 

    Dynamic modeling and simulation of brushless doubly fed induction machine in consideration of core loss

    , Article IECON Proceedings (Industrial Electronics Conference) ; 2012 , Pages 1753-1757 ; 9781467324212 (ISBN) Hashemnia, M. N ; Tahami, F ; The Institute of Electrical and Electronics Engineers (IEEE); IEEE Industrial Electronics Society (IES) ; Sharif University of Technology
    2012
    Abstract
    Brushless doubly fed induction machine has recently attracted attention in variable speed generators and motor drives. In order to have a high performance control, a precise dynamic model is required. This paper aims at introducing a model of brushless doubly fed induction machine taking core loss into account. The details of model derivation are outlined and the torque relation is expressed in the general reference frame. The model is then used for simulation of the dynamic performance of the machine. The error introduced by neglecting core loss effect is also shown  

    A modified DTC for induction motor drive system fed by Indirect Matrix Converter using Active Learning Method

    , Article 2011 2nd Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2011, 16 February 2011 through 17 February 2011 ; February , 2011 , Pages 356-361 ; 9781612844213 (ISBN) Faraji, V ; Aghasi, M ; Khaburi, D. A ; Ghorbani, M. J ; Sharif University of Technology
    2011
    Abstract
    This paper presents a high performance Direct Torque Control (DTC) theme for the induction motor using Indirect Matrix Converter (IMC). To improve the dynamic behavior of motor, Active Learning Method (ALM) is implemented on the DTC. The ALM uses its own modeling technique called the ink drop spread (IDS) method. Functionally the IMC is very similar to the Direct Matrix Converter (DMC) but it has separate line and load bridges. In the inverter stage, the classical DTC method is employed. In the rectifier stage, in order to reduce losses caused by snubber circuit the rectifier four-step commutation method is employed. By suitably selecting switching pattern and using Active Learning Method... 

    A variable switching frequency control method for active front end multilevel rectifier

    , Article 17th IEEE International Conference on Environment and Electrical Engineering and 2017 1st IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2017, 6 June 2017 through 9 June 2017 ; 2017 ; 9781538639160 (ISBN) Ouni, S ; Khodabandeh, M ; Zolghadri, M. R ; Rodriguez, J ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    Conventional back-to-back converters with input power factor correction are still the best solution for motor drive applications which are usually subjected to considerable load changes during their operation. Since converter components, especially input-side inductances are designed for nominal power rating, the rated input power factor and input current distortion aren't achievable in light loads. In this paper a control method is proposed to improve the input current distortion and input power factor in light loads. This is achieved by increasing the switching frequency according to the reduction in load. Since conduction and switching losses decrease in light loads, the overall losses by... 

    Active damping of torsional vibrations due to the sub-harmonic instability on a synchronous generator

    , Article 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe, 17 September 2018 through 21 September 2018 ; 2018 ; 9789075815283 (ISBN) Peyghami, S ; Azizi, A ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Sub-harmonic stability issues due to the interaction between a load-commutated motor drive and a synchronous turbo-generator train in a Liquefied Natural Gas (LNG) station are studied in this paper. The sub-harmonic current injected by motor drives may excite the mechanical torsional modes of turbogenerator train. In this paper, the electro-mechanical interaction phenomenon is investigated and an active damper is proposed to absorb the sub-harmonic currents of motor drives and increase the damping of the electro-mechanical system. Simulations and experiments validate the instability problem and effectiveness of the proposed solution. © 2018 EPE Association