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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) ; 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...
Design of an optimum torque actuator for augmenting lower extremity exoskeletons in biomechanical framework
, Article 2011 IEEE International Conference on Robotics and Biomimetics, ROBIO 2011 ; 2011 , Pages 1979-1983 ; 9781457721373 (ISBN) ; Ghafari, A. S ; Meghdari, A ; Sharif University of Technology
Abstract
This research presents virtual prototyping and performance evaluation of a series elastic torque actuator developed for augmenting lower extremity exoskeletal systems employing biomechanical framework. For this purpose, experimental kinematical data of the lower extremity were collected for walking and backpack load carrying. Forward dynamics simulation of the movements under investigation is performed in a biomechanical framework consisting of a musculoskeletal model with ten degrees-of-freedom actuated by eighteen Hill-type musculotendon actuators per leg to perform the muscle functional analysis. Muscle torque analysis results employed for optimal design and selection of components in the...
Direct torque control of brushless doubly fed induction machine
, Article International Journal of Control and Automation ; Volume 3, Issue 4 , 2010 , Pages 5- ; 20054297 (ISSN) ; Khayyat, A. A ; Sharif University of Technology
2010
Abstract
This article contributes a torque control based on hysteresis for Brushless Doubly Fed Induction Machine (BDFM) through machine analysis and extracting the d-q parameters that influence on the machine behavior. In this research, a Direct Torque Control (DTC) based on stator flux-oriented vectors and machine's relation and equations with voltage and current of both stators have been introduced. The control for the BDFM is implemented by a voltage source inverter connected to the second stator as a torque controller that uses the classical field-oriented control method widely used in voltage sector selection. Finally BDFM as a closed loop model with DTC is simulated and evaluated
Direct torque control of induction motor by active learning method
, Article PEDSTC 2010 - 1st Power Electronics and Drive Systems and Technologies Conference, 17 February 2010 through 18 February 2010, Tehran ; 2010 , Pages 267-272 ; 9781424459728 (ISBN) ; Akhbari, M ; Mokhtari, H ; Sharif University of Technology
2010
Abstract
This paper presents a high performance direct torque control (DTC) theme for the induction motor (IM). To solve those problems associated with conventional DTC, such as flux and torque ripple, variable switching frequency, inaccuracy in motor model and other parts of system. The Active Learning Method (ALM) is implemented on the DTC. In the Active Learning Method for information modeling, a method known as Ink Drop Spread (IDS) is used. The simulation results of DTC system based on ALM and the comparison of motor performance under the proposed control system with respect to those obtained under conventional DTC confirms its effectiveness and accuracy
Failure detection and isolation in robotic manipulators using joint torque sensors
, Article Robotica ; Volume 28, Issue 4 , 2010 , Pages 549-561 ; 02635747 (ISSN) ; Aghili, F ; Sharif University of Technology
2010
Abstract
Reliability of any model-based failure detection and isolation (FDI) method depends on the amount of uncertainty in a system model. Recently, it has been shown that the use of joint torque sensing results in a simplified manipulator model that excludes hardly identifiable link dynamics and other nonlinearities such as friction, backlash, and flexibilities. In this paper, we show that the application of the simplified model in a fault detection algorithm increases reliability of fault monitoring system against modeling uncertainty. The proposed FDI filter is based on a smooth velocity observer of degree 2n where n stands for the number of manipulator joints. No velocity measurement and...
Friction stir butt welding of Al-Cu bilayer laminated composites: analysis of force, torque, and temperature
, Article International Journal of Advanced Manufacturing Technology ; Volume 88, Issue 1-4 , 2017 , Pages 393-400 ; 02683768 (ISSN) ; Kazeminezhad, M ; Zarezadeh Mehrizi, M ; Eisaabadi, B. G ; Loureiro, A ; Sharif University of Technology
Abstract
The effect of the layer in contact with tool (Al or Cu) and the depth of plunge on friction stir butt welding of Al-Cu bilayer laminated composites produced by cold roll welding were studied. The measurement of weld cross sections and variations of the axial load and torque during welding process showed that material flow is influenced by the material which is in contact with the shoulder. Being Al layer in contact with the shoulder led to higher force and torque during welding, and a defect-free weld could be obtained in this manner. By welding from Cu side, a higher plunge depth was needed to develop enough force and torque and thereby a defect-free weld. The amount of material swept by...
The Control of an exoskeleton and the reduction of interaction force using human intent detection by EMG signals and torque estimation
, Article Proceedings of the 6th RSI International Conference on Robotics and Mechatronics, IcRoM 2018, 23 October 2018 through 25 October 2018 ; 2019 , Pages 536-541 ; 9781728101279 (ISBN) ; Vossoughi, G. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Disability and motor disorders are some of the problems that people may face due to some factors such as accident, spinal cord injuries, brain damage, and the presence of a problem in neurological commands due to stroke. One of the proposed methods for solving the problems of these people is the use of exoskeletons to generate movement. The main goal of this paper is the control of Sharif Exoskeleton Robot and the reduction of interaction force between user and robot by using human intent detection. This goal is done by estimating the knee torque of one degree of freedom in a swing phase using Hill model based on the EMG data from the thigh muscles. Accordingly, the calibration algorithm is...
Implementation and intelligent gain tuning feedback–based optimal torque control of a rotary parallel robot
, Article JVC/Journal of Vibration and Control ; Volume 28, Issue 19-20 , 2022 , Pages 2678-2695 ; 10775463 (ISSN) ; Ebrahimi Toulkani, N ; Sharif University of Technology
SAGE Publications Inc
2022
Abstract
Aiming at operating optimally minimizing error of tracking and designing control effort, this study presents a novel generalizable methodology of an optimal torque control for a 6-degree-of-freedom Stewart platform with rotary actuators. In the proposed approach, a linear quadratic integral regulator with the least sensitivity to controller parameter choices is designed, associated with an online artificial neural network gain tuning. The nonlinear system is implemented in ADAMS, and the controller is formulated in MATLAB to minimize the real-time tracking error robustly. To validate the controller performance, MATLAB and ADAMS are linked together and the performance of the controller on the...
Using axiomatic design theory for selection of the optimum design solution and manufacturing process plans of a limited angle torque motor
, Article Journal of Manufacturing Science and Engineering, Transactions of the ASME ; Vol. 136, Issue. 5 , 2014 ; ISSN:1096-6668 ; Houshmand, M ; Nasiri-Zarandi, R ; Mirsalim, M ; Sharif University of Technology
Abstract
The brushless dc limited angle torque motor (LATM) has been widely used in areas of aerospace equipments, robot drives, optical scanning systems and any drive systems that require limited motion, ranging from the simple ON-OFF servo valves to the accurate tracking of a reference signal. This paper presents the optimum design procedure of a brushless direct current LATM to satisfy the functional requirements (FRs) and constraints using Independence axiom in axiomatic design (AD) approach. Also, to select the best manufacturing process plan, we consider both cost and thermal performance as two effective criteria, and evaluate available alternatives by computing information content in...
A new configuration of switched reluctance motor for reducing the torque ripple
, Article 2009 International Conference on Electric Power and Energy Conversion Systems, 10 November 2009 through 12 November 2009 ; 2009 ; 9789948427155 (ISBN) ; Oraee, H ; Kaboli, S ; Dorkhah, M. R ; Sharif University of Technology
Abstract
Switched reluctance motors (SRM) are one of the most reliable and cost effective motors and their applications are increasing in industry. However, it suffers from high level of torque ripple. In this paper, a new configuration for stator and rotor of SRM is presented. In the proposed method, a new saliency is developed to remove negative torque and therefore decrease torque ripple and acoustic noise, increase efficiency and as a result, expand speed range. The simulation results demonstrate that the new motor structure has a smooth torque profile with possibility to work at higher speed lower acoustic noise
Experimental investigation on the micro-step control disturbance rejection under random excitations
, Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beach, CA, 24 September 2005 through 28 September 2005 ; Volume 1 B , 2005 , Pages 1747-1751 ; 0791847381 (ISBN) ; Behzad, M ; Sharif University of Technology
2005
Abstract
Effect of random signals with various powers, as current loads, on positioning and disturbance rejection problems on micro-step PID closed loop control system is addressed in this paper. Experimental results due to implementing different white noise power, speed, and a 0.3 N.m disturbance load torque show that, Random noise source changes current profile and affects the accuracy of positioning in tracking and disturbance rejection problems. Performance of the PID proposed controller under the implementation of random noise on phases of the HSM has been proved to be accurate enough even under disturbance torque acting on the system. Copyright © 2005 by ASME
Adaptive Compensation of Effect of Slow Dynamic Actuators in Robots Without Output Torque Measurement
, M.Sc. Thesis Sharif University of Technology ; Namvar, Mehrzad (Supervisor)
Abstract
A motion tracking control design of an n-DOF rigid robot by taking into account its actuator dynamics is proposed in this paper using backstepping technique. neglecting actuator dynamics in control of rigid robot manipulators can degrade the performance and loss of stability. However,consideration of actuator dynamics entails joint torque or armature currents measurement. In this study, torque measurement has been avoided using an torque estimator.. Finally, Semi-global convergence for motion tracking error are proven. In addition, A simulation example of a two-link robotic manipulator is also given to clarify the effectiveness of proposed design method. Considering actuator dynamics entails...
Robotic Modeling of Paraplegic Locomotion to Improve the Gait Efficiency Using Modified Motion Pattern and Orthotics Design
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor)
Abstract
Walking on legs using orthosis for spinal cord injury patients has many advantages and decreases the physiological and psychological problems comparing with wheelchair application, however high energy consumption and early exhaustion of patients are disadvantages of orthosis usage. The most important group of orthosis for spinal cord injury patients is RGO (Reciprocating Gait Orhtosis) which a reciprocating cable mechanism links two hip joints motion. So swinging of mobile leg gets easier and stability of patient in standing and walking step increases. Regarding to existent reports about high energy consumption in walking by orthosis, this project has been fulfilled to design an improved...
A fast flux search controller for DTC-based induction motor drives
, Article IEEE Transactions on Industrial Electronics ; Volume 54, Issue 5 , 2007 , Pages 2407-2416 ; 02780046 (ISSN) ; Zolghadri, M. R ; Vahdati Khajeh, E ; Sharif University of Technology
2007
Abstract
In this paper, a flux search controller is proposed to increase the efficiency of a direct torque-controlled induction motor in full load range. The value of the flux reference is determined through a minimization algorithm. The amplitude of stator current is used as the objective function since it is shown that samples of the stator current have better statistical properties than input power. In addition, the stator current has more sensitivity to the flux variation than input power. These two properties allow implementing an adaptive algorithm to determine the proper flux step without waste of time. The minimum allowable value of the flux step has been determined based on this process to...
Modelling of an ultrasonic motor based on hammerstein model structure
, Article 8th International Conference on Control, Automation, Robotics and Vision (ICARCV), Kunming, 6 December 2004 through 9 December 2004 ; Volume 2 , 2004 , Pages 1374-1378 ; 0780386531 (ISBN) ; Haeri, M ; Sharif University of Technology
2004
Abstract
Ultrasonic motors (USM) possess heavy nonlinear and load dependent characteristics of ultrasonic motors (USM) such as dead-zone and saturation reverse effects, which vary with driving conditions. In this paper, behaviour of an ultrasonic motor is modelled using Hammerstein model structure and experimental measurements. Simulation results show the good matching between the developed model and experimental measurements. © 2004 IEEE
Flux harmonic spectrum proccessing of direct torque controlled induction motor
, Article Proceedings of the 2003 IEEE International Symposium on Circuits and Systems, Bangkok, 25 May 2003 through 28 May 2003 ; Volume 3 , 2003 , Pages III383-III386 ; 02714310 (ISSN) ; Zolghadri, M. R ; Sharif University of Technology
2003
Abstract
Flux spectrum is greatly influenced by flux and torque controller hysteresis loops (dead bands) in direct torque control of AC motors. On the other hand iron loss in induction motor is closely related to flux harmonics. Hence flux spectrum must be observed in control process to minimize the motor losses. In this paper the relation between the magnetic-flux spectrum and electromagnetic-torque and magnetic-flux controller hysteresis loops (dead bands) as well as machine parameters is investigated. Simulation results are presented to justify the results
High-endurance and performance-efficient design of hybrid cache architectures through adaptive line replacement
, Article Proceedings of the International Symposium on Low Power Electronics and Design ; 2011 , p. 79-84 ; ISSN: 15334678 ; ISBN: 9781612846590 ; Arjomand, M ; Sarbazi-Azad, H ; Sharif University of Technology
Abstract
In this paper, we propose a run-time strategy for managing writes onto last level cache in chip multiprocessors where STT-RAM memory is used as baseline technology. To this end, we assume that each cache set is decomposed into limited SRAM lines and large number of STT-RAM lines. SRAM lines are target of frequently-written data and rarely-written or read-only ones are pushed into STT-RAM. As a novel contribution, a low-overhead, fully-hardware technique is utilized to detect write-intensive data blocks of working set and place them into SRAM lines while the remaining data blocks are candidates to be remapped onto STT-RAM blocks during system operation. Therefore, the achieved cache...
Performance of the brushless doubly-fed machine under normal and fault conditions
, Article IET Electric Power Applications ; Volume 6, Issue 9 , Volume 6, Issue 9 , 2012 , Pages 621-627 ; 17518660 (ISSN) ; Zolghadri, M. R ; Oraee, H ; Tavner, P ; Abdi, E ; Logan, T ; Sharif University of Technology
2012
Abstract
In this study, the steady-state operation of the brushless doubly-fed machine (BDFM) in various modes is physically elaborated and the active power flow and torque analysis are presented for each operating mode alongside confirmatory experimental results on a 4/8 pole D160 size machine. The machine behaviour in asynchronous operating modes is described similar to the conventional induction machines with corresponding pole numbers. Moreover, its performance in synchronous mode is shown to be similar to synchronous machines. On the basis of the above, the BDFM performance is further analysed under two possible fault conditions: first, a controller or converter fault leading to loss of...
A predictive loss minimisation direct torque control of permanent magnet synchronous motors
, Article Australian Journal of Electrical and Electronics Engineering ; Volume 9, Issue 1 , 2012 , Pages 89-98 ; 1448837X (ISSN) ; Vaez Zadeh, S ; Tahami, F ; Sharif University of Technology
2012
Abstract
Although permanent magnet synchronous motors (PMSMs) are inherently of high efficiency, their efficiency is enormously dependent on their control strategy. The purpose of this paper is to improve the efficiency of PMSMs under a direct torque control (DTC) method. The main idea behind the proposed method is to predict a required small change of the statorflux amplitude at each sampling period to reduce the machine electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to change the flux amplitude in a xvay that the electrical loss decreases. The results of simulation show significant improvement in the...
Flux estimation by asymmetric carrier injection for sensorless direct torque control of PMSM
, Article 2012 3rd Power Electronics and Drive Systems Technology, PEDSTC 2012, 15 February 2012 through 16 February 2012 ; February , 2012 , Pages 44-50 ; 9781467301114 (ISBN) ; Tahami, F ; Sharif University of Technology
2012
Abstract
The combination of direct torque control and permanent magnet synchronous motors (PMSMs) provides a highly dynamic drive. In this paper direct torque control method of PMSM is merged with a sensorless control algorithm and a robust flux observer is proposed which results in a high performance highly reliable drive. First a high frequency signal injection method within DTC algorithm is introduced to estimate the rotor position of PMSM. Then the method is modified in order to estimate stator dynamic inductances. The stator inductances are then used in a current model flux observer