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permanent-magnets
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Prediction of chaos in non-salient permanent-magnet synchronous machines
, Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 377, Issue 1-2 , December , 2012 , Pages 73-79 ; 03759601 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
2012
Abstract
This Letter tries to find the area in parameter space of a non-salient Permanent-Magnet Synchronous Machine (PMSM) in which chaos can occur. This area is briefly named as chaotic area. The predicted chaotic area is obtained by checking some conditions which are necessary for existence of chaos in a dynamical system. In this Letter, it is assumed that this machine is in the generator mode, and its model is based on direct and quadrature axis of stator voltages and currents. The information of the predicted area is used in non-chaotic maximum power control of torque in the machine
A loss minimization control strategy for direct torque controlled interior permanent magnet synchronous motors
, Article Journal of Power Electronics ; Volume 9, Issue 6 , 2009 , Pages 940-948 ; 15982092 (ISSN) ; Vaez Zadeh, S ; Tahami, F ; Sharif University of Technology
2009
Abstract
The main objective of this a paper is to improve the efficiency of permanent magnet synchronous motors (PMSMs) by using an improved direct torque control (DTC) strategy. The basic idea behind the proposed strategy is to predict the impact of a small change in the stator flux amplitude at each sampling period to decrease electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to fulfill the flux change. The motor drive simulations confirm a significant improvement in efficiency as well as a very fast and smooth response under the proposed strategy
Experimental investigation on the fault diagnosis of permanent magnet DC electromotors
, Article Insight: Non-Destructive Testing and Condition Monitoring ; Volume 55, Issue 8 , August , 2013 , Pages 422-427 ; ISSN: 13542575 ; Ebrahimi, A ; Heydari, M ; Asadi, M ; Alasti, A ; Sharif University of Technology
Abstract
In this paper, an algorithm for fault diagnosis of permanent magnet DC electromotors.has been investigated, based on vibration and electrical current monitoring. Several permanent magnet DC electromotors.with previously determined faults have been prepared and the vibration, current and speed data have been measured. The relationship between certain related measured data and faults has been determined. A fault diagnosis algorithm has been developed in this research based on these relationships. This algorithm can be used in mass production lines for quality control
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...
Maximum torque per ampere control of permanent magnet synchronous motor using genetic algorithm
, Article Telkomnika ; Volume 9, Issue 2 , 2011 , Pages 237-244 ; 16936930 (ISSN) ; Nademi, H ; Rezaei, M ; Sharif University of Technology
Abstract
Permanent magnet synchronous motor (PMSM) drives have many advantages over other drives, i.e. high efficiency and high power density. Particularly, PMSMs are epoch-making and are intensively studied among researchers, scientists and engineers. This paper deals with a novel high performance controller based on genetic algorithm. The scheme allows the motor to be driven with maximum torque per ampere characteristic. In this paper assuming an appropriate fitness function, the optimum values for d-axis current of motor set points at each time are found and then applied to the controller. Simulation results show the successful operation of the proposed controller
Cogging force mitigation techniques in a modular linear permanent magnet motor
, Article IET Electric Power Applications ; Volume 10, Issue 7 , 2016 , Pages 667-674 ; 17518660 (ISSN) ; Nasiri Gheidari, Z ; Sharif University of Technology
Institution of Engineering and Technology
Abstract
Modular linear doubly salient permanent magnet motors are well adapted to linear propulsion systems because of their distinct characteristics, such as high efficiency and power density, reduced maintenance and initial cost, low noise and permanent magnet (PM) leakage flux, and fault tolerance capability. However, such motors suffer from high cogging thrust. In this study, various techniques based on previously proposed methods for PM machines are applied on the studied motor and evaluated by using non-linear three-dimensional time-stepping finite element analysis; three novel, optimised techniques are then presented. The techniques presented are based on the minimisation of the variation in...
Prediction and Control of Chaos in Permanent Magnet Synchronous Machines
, M.Sc. Thesis Sharif University of Technology ; Tavazoei, Mohammad Saleh (Supervisor)
Abstract
Synchronous machines is one of the most popular machines in industry and in power plants. Because the dynamic of this machine is nonlinear, it can exhibit complex behaviors. In this project we have studied a special case in Permanent Magnet Synchronous Machines. A case in which speed of rotor, frequency, currents amplitude and voltages amplitude change in an irregular manner. This special case is called chaos. Chaos occurs for some specific values of parameters and inputs. In this study in the first step, we have tried to find the chaotic area of parameters of system (Prediction of chaos). Then in the next step, we have designed some controllers which can eliminate chaos in the system. The...
Sensorless control of non-salient PMSM using simultaneous injection of two HF signals
, Article Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC ; March , 2014 , p. 2463-2468 ; Yaghoubi, M ; Tahami, F ; Bakhshai, A ; Jain, P. K ; Sharif University of Technology
Abstract
In recent years sensorless techniques based on HF carrier injection have become very popular as they are capable to estimate rotor position in a wide speed range. They can provide precise control over interior PMSMs without the accompanying need for a position sensor. However, in surface-mounted PMSMs, the estimation of rotor position is only reliable at light loads due to the very small saliency arising from main flux saturation. The anisotropy caused by stator flux saturation is not necessarily in alignment with rotor position especially at heavy loads. In this paper a novel solution is proposed to make use of the sensorless scheme in a surface-mounted PMSM even at heavy loads
A general analytical approach to reach maximum grid support by PMSG-based wind turbines under various grid faults
, Article Journal of Central South University ; Volume 26, Issue 10 , 2019 , Pages 2833-2844 ; 20952899 (ISSN) ; Ajami, A ; Mokhtari, H ; Hojabri, H ; Sharif University of Technology
Central South University of Technology
2019
Abstract
A novel fault ride-through strategy for wind turbines, based on permanent magnet synchronous generator, has been proposed. The proposed strategy analytically formulates the reference current signals, disregarding grid fault type and utilizes the whole system capacity to inject the reactive current required by grid codes and deliver maximum possible active power to support grid frequency and avoid generation loss. All this has been reached by taking the grid-side converter’s phase current limit into account. The strategy is compatible with different countries’ grid codes and prevents pulsating active power injection, in an unbalanced grid condition. Model predictive current controller is...
Optimal design of a flux reversal permanent magnet machine as a wind turbine generator
, Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 28, Issue 2 , 2020 , Pages 693-707 ; Tahami, F ; Nasiri Gheidari, Z ; Sharif University of Technology
Turkiye Klinikleri
2020
Abstract
Flux reversal permanent magnet generators are well suited for use as wind turbine generators owing to their high torque generation ability and magnetic gear. However, they suffer from poor voltage regulation due to their high winding inductance. In this paper, a design optimization method is proposed for flux reversal generators in wind turbine applications. The proposed method includes a new multiobjective function. Cost, volume of the generator, and mass of the permanent magnet are considered in it independently and simultaneously. Besides the new objective function, the main superiority of this paper compared with published papers is considering winding inductance in optimization...
Production of (Nd,MM)2(Fe,Co,Ni)14B-type sintered magnets using a binary powder blending technique
, Article Journal of Alloys and Compounds, Lausanne ; Volume 298, Issue 1-2 , 2000 , Pages 319-323 ; 09258388 (ISSN) ; Kianvash, A ; Seyyed Reihani, M ; Yoozbashi Zadeh, H ; Sharif University of Technology
Elsevier Science S.A
2000
Abstract
The anisotropic (Nd,MM)2(Fe,Co,Ni)14B-type magnets were produced using the binary alloy sintering method (MM denotes a Misch-metal). The composition of the master alloy was close to stoichiometric Nd2Fe14B compound, while that of the sintering aid was MM38.2Co46.4Ni15.4. The microstructures of sintered magnets were investigated using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray detector (EDX). X-ray diffractometry (XRD) was also employed for phase analysis. The optimum magnetic properties were obtained for a composition of Nd11.9MM2.9Fe73.9Co3.3Ni1.1B6.9 made of 90 wt.% master alloy and 10 wt.% sintering aid. The two main phases, i.e. the (RE)2(TM)14B phase...
Sensorless control of non-salient PMSM using asymmetric alternating carrier injection
, Article 2011 IEEE Symposium on Industrial Electronics and Applications, ISIEA 2011, 25 September 2011 through 28 September 2011 ; September , 2011 , Pages 7-12 ; 9781457714184 (ISBN) ; Tahami, F ; Sharif University of Technology
Abstract
Sensorless control of permanent magnet synchronous motors allows reducing cost and complexity, and increasing mechanical robustness and noise immunity. Sensorless methods based on high frequency carrier injection have attracted considerable attention in recent years as they can estimate rotor position in a wide speed range. These methods employ anisotropic properties of rotor to estimate rotor position in ac machines. With internal permanent magnet motors, the high frequency signal injection method can deliver precise sensorless control, however in surface-mounted permanent magnet machines, where a small saliency arises from main flux saturation, the estimation of rotor magnet position is...
Proposal of a Modular Structure and a Load Sharing Strategy among Back to Back Converters for Wind Turbines
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
The utilization of wind power has been increasing in recent years which lead to enhance the the usage of wind power capacity in the range of MegaWatt. However, due to the limitation ofswitching devices capacity, which exists in power electronic converters, improving the capacity of wind power generation is not accessible. Thus, a feasible solution for this problem is paralleling power electronics converters, which increases both the capacity of power generation and the reliability of wind turbine systems. Nevertheless, paralleling converters may cause a circulating-current which brings current discrepancy, current waveform distortion, power losses, increase in THD of currents, and reduction...
Performance Analysis, Optimization and Prototyping of Doubly Salient PM Vernier Generators
, M.Sc. Thesis Sharif University of Technology ; Oraee, Hashem (Supervisor) ; Nasiri-Gheidari, Zahra (Supervisor)
Abstract
In this thesis, no-load and full-load performance of Permanent Magnet Vernier Generators (PMVGs) is investigated in fully-aligned condition and under different types of mechanical faults. The studied mechanical faults are Static Eccentricity (SE), Dynamic Eccentricity (DE), Inclined Rotor (IR), and Run-out (RO). Furthermore, an analytical model is also developed to calculate the permeance of the air-gap and the induced voltages in the health machine and under studied mechanical faults. Then, 2-D and 3-D non-linear, time stepping finite element method is utilized for performance evaluation of the generator in no-load and full-load (with resistive, inductive and capacitive loads). In continue,...
Resonance frequencies and stability of two flexible permanent magnetic beams facing each other
, Article Journal of Sound and Vibration ; Volume 331, Issue 26 , 2012 , Pages 5745-5754 ; 0022460X (ISSN) ; Mohammadkhani, H ; Sharif University of Technology
2012
Abstract
This paper aims at investigating the interaction of two flexible permanent magnet beams facing each other. The governing equations of motion are obtained based on the Euler-Bernoulli beam model along with Hamiltons principle. Assuming that the beams tips are far enough, each magnet beam is considered as a series of dipole segments and the external force and moment distributions over each beam due to the magnetic field of the other one is calculated in the deformed configuration. The transverse deflections of the beams are written as series expansions of the mode shapes of an unloaded cantilever beam and the Galerkin method is applied to determine the stability and resonance frequencies....
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
Performance verification of saturated IPM bearingless motors considering magnetic pull variation
, Article Proceedings - 2016 IEEE International Power Electronics and Motion Control Conference, PEMC 2016, 25 September 2016 through 28 September 2016 ; 2016 , Pages 643-649 ; 9781509017980 (ISBN) ; Nasiri Gheidari, Z ; Rahman, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Interior permanent magnet (IPM) bearingless motors are becoming a good choice for high-speed applications. In these motors, reducing the thickness of the PM leads to the increase of the radial forces which affects the demagnetizing fields. Various types of PM motors have so far been recommended for enhancement of the radial forces and torque. In the proposed IPM motor the d-axis flux-linkage and the q-axis torque component are raised due to the armature reaction and this saturates the stator teeth. In addition, the magnetic attraction force generated by displacement force depends on the armature reaction. The mathematical model of IPM bearingless motor based on the dq transformation,...
Longitudinal end effect in a variable area linear resolver and its compensating methods
, Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 1316-1321 ; 9781538649169 (ISBN) ; Nasiri Gheidari, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Linear permanent magnet machines are increasingly used in industrial applications where they need position sensors to improve their performance. Variable Reluctance resolvers are one the best position sensors that can be used in unfriendly environment conditions, with high mechanical vibration, wide temperature variation and polluted environments. However, conventional VR resolvers suffer from complicated winding process, undesirable performance under eccentricities, and high position error in two-pole applications. So, in this paper a new linear resolver is proposed based on the sinusoidal variation of common area between the moving and the stationary parts. Then, the influence of...
Stand alone performance of permanent magnet synchronous wind power generator with current source matrix converter
, Article Electric Power Components and Systems ; Volume 43, Issue 8-10 , 2015 , Pages 1018-1027 ; 15325008 (ISSN) ; Mokhtari, H ; Chang, L ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
A matrix converter is a voltage/current source AC/AC frequency converter. In grid-connected operation of a variable-speed permanent magnet synchronous wind power generator, the matrix converter is normally controlled as a voltage source converter. In this control method, the generator-side voltage is synthesized from the grid-side voltage source. However, in the stand-alone mode of operation, the grid-side stiff voltage source is not available, and the input filter of the matrix converter is unstable. In this article, a new control method is presented that controls a permanent magnet synchronous wind generator in a stand-alone mode with a matrix converter as a current source converter. The...
Simulation and experimental study of real-time robust control of hybrid stepper motor with QFT method in micro-step operation
, Article Proceedings of the IEEE International Conference on Mechatronics 2004, ICM'04, Istanbul, 3 June 2004 through 5 June 2004 ; 2004 , Pages 364-368 ; 0780385993 (ISBN) ; Vossoughi, G. R ; Sharif University of Technology
2004
Abstract
Real-time linear robust control of a two phase hybrid stepper motor with Quantitative Feedback Theory method in micro-stepping operation is considered in this paper. Utilizing the phase currents as inputs, linear robust controller is derived for a Hybrid Stepper Motor that achieves robustness to parametric and dynamic uncertainties such as viscous friction, load torque, flux linkage and other uncertainties. Simulation and experimental studies are presented to show the efficiency of the control design approach