Showing 34 results for Synchro
A.vahedi, M.ramezani,
Volume 1, Issue 2 (4-2005)
Abstract
Dc excitation of the field winding in a synchronous machine can be provided by
permanent magnets. Permanent magnet synchronous machine (PMSM) can offer simpler
construction, lower weight and size for the same performance, with reduced losses and higher
efficiency. Thanks to the mentioned advantages these motors are widely used in different
application, therefore analysis and modeling of them, is very important. In this paper a new, fast
and simple method is presented to study performance of a PMSM connected to the converter.
For this purpose, average-value modeling and related analytical relations which leads to the
desired characteristics such as electromagnetic torque, dc current and dc voltage is presented
and applied to PMSM & converter system. The advantage of this model lie in reduction of
computation time compares to the other dynamic models while keeping accuracy quite
acceptable. This model is applicable for studying the steady-state performance of systems as
well as dynamic performance.
R. Kharel, K. Busawon, Z. Ghassemlooy,
Volume 4, Issue 4 (12-2008)
Abstract
In this paper, we propose a new chaos-based communication scheme using the observers. The novelty lies in the masking procedure that is employed to hide the confidential information using the chaotic oscillator. We use a combination of the addition and inclusion methods to mask the information. The performance of two observers, the proportional observer (P-observer) and the proportional integral observer (PI-observer) is compared that are employed as receivers for the proposed communication scheme. We show that the P-observer is not suitable scheme since it imposes unpractical constraints on the messages to be transmitted. On the other hand, we show that the PI-observer is the better solution because it allows greater flexibility in choosing the gains of the observer and does not impose any unpractical restrictions on the message.
K. Malekian, J. Milimonfared, B. Majidi,
Volume 5, Issue 1 (3-2009)
Abstract
The main theme of this paper is to present novel controller, which is a genetic
based fuzzy Logic controller, for interior permanent magnet synchronous motor drives with
direct torque control. A radial basis function network has been used for online tuning of the
genetic based fuzzy logic controller. Initially different operating conditions are obtained
based on motor dynamics incorporating uncertainties. At each operating condition, a
genetic algorithm is used to optimize fuzzy logic parameters in closed-loop direct torque
control scheme. In other words, the genetic algorithm finds optimum input and output
scaling factors and optimum number of membership functions. This optimization procedure
is utilized to obtain the minimum speed deviation, minimum settling time, zero steady-state
error. The control scheme has been verified by simulation tests with a prototype interior
permanent magnet synchronous motor.
M. Shahnazari, A. Vahedi,
Volume 5, Issue 4 (12-2009)
Abstract
An accurate average value model of synchronous machine-rectifier system considering the effect of stator resistance is derived in this paper. A proper voltage-behind-reactance synchronous machine model without any approximations is used for the generator that allows effective calculation of commutation displacement angle. All rectification modes of the rectifier are studied. A detailed switching model is implemented and validated against experimental measurements. The described average value model is evaluated through comparison of detailed simulation results and average model in time domain.
A. Damaki Aliabad, M. Mirsalim, M. Fazli Aghdaei,
Volume 6, Issue 1 (3-2010)
Abstract
The air-gap of electrical machines may become non-uniform due to low accuracy of the manufacturing machinery, in assembling processes, or by aging. Detection and monitoring of this phenomenon is very important and of interest. There are several methods to model non-uniform air-gaps and to detect them by monitoring systems. One of the most widely used methods is by the analysis of the line currents. In this paper a new, simple and comprehensive method is presented to model and detect non-uniform air-gaps in synchronous generators with skewed rotors. The influence of non-uniform air-gaps on the harmonics of the induced voltage of the stator is investigated by the proposed method. Simulations are performed for three cases: uniform air-gap, static rotor eccentricity, and stator ovality in a two phase generator. The experimental results are also presented. The good correspondence between the simulation and the experimental results clearly validates the theoretical findings put forward in this paper.
A. Jabbari, M. Shakeri, S. A. Nabavi Niaki,
Volume 6, Issue 1 (3-2010)
Abstract
In the present work, an integrated method of pole shape design optimization for reduction of torque pulsation components in permanent magnet synchronous motors is developed. A progressive design process is presented to find feasible optimal shapes. This method is applied on the pole shape optimization of two prototype permanent magnet synchronous motors, i.e., 4-poles/6-slots and 4-poles-12slots.
C. Lucas , Z. Nasiri-Gheidari , F. Tootoonchian,
Volume 6, Issue 4 (12-2010)
Abstract
In this paper particle swarm optimization (PSO) is used for a design optimization of a linear permanent magnet synchronous motor (LPMSM) considering ultra low thrust force ripples, low magnet consumption, improved efficiency and thrust. The influence of PM material is discussed, too and the modular poles are proposed to achieve the best characteristic. PM dimensions and material, air gap and motor width are chosen as design variables. Finally 2-D finite element analyses validate the optimization results.
H. Yaghobi, K. Ansari, H. Rajabi Mashhadi,
Volume 7, Issue 4 (12-2011)
Abstract
A reliable and accurate diagnosis of inter-turn short circuit faults is a challenging problem in the area of fault diagnosis of electrical machines. The purpose of this challenge is to be more efficient in fault detection and to provide a reliable method with low-cost sensors and simple numerical algorithms which not only detect the occurrence of the fault, but also locate its position in the winding. Hence, this paper presents a novel method for diagnosis of different kinds of inter-turn winding faults in a salient-pole synchronous generator using the change in the magnetic flux linkage. It describes the influence of inter-turn winding faults on the magnetic flux linkage distribution of the generator. The main feature of the proposed method is its capability to identify the faulty coils under two types of inter-turn winding faults. Also, simple algorithm, low cost sensor and sensitivity are the other feature in the proposed technique. In this method, generator air gap flux linkage is measured via search coils sensor installed under the stator wedges. Theoretical approach based on Finite Element Method (FEM) together with experimental results derived from a 4-pole, 380U, 1500 rpm, 50 Hz, 50 KVA, 3-phase salient-pole synchronous generator confirm the validity of the proposed method.
J. Soleimani, A. Vahedi, S. M Mirimani,
Volume 7, Issue 4 (12-2011)
Abstract
Recently, Inner permanent magnet (IPM) synchronous machines have been
introduced as a possible traction motor in hybrid electric vehicle (HEV) and traction
applications due to their unique merits. In order to achieve maximum torque per ampere
(MTPA), optimization of the motor geometry parameters is necessary. This paper Presents
a design method to achieve minimum volume, MTPA and minimum value of cogging
torque for traction IPM synchronous machines and simulation in order to extract the output
values of motor is done using 3D-Finite Element Model, that has high level of accuracy and
gives us a better insight of motor performance. Then presents back EMF, power factor,
cogging torque, Flux density, torque per ampere diagram, CPSR (constant power speed
ratio), torque per speed diagram in this IPM synchronous machine. This study can help
designers in design approach of such motors.
M. H. Refan, H. Valizadeh,
Volume 8, Issue 3 (9-2012)
Abstract
Accurate and reliable time is necessary for financial and legal transactions, transportation, distribution systems, and many other applications. Time synchronization protocols such as NTP (the Network Time Protocol) have kept clocks of such applications synchronized to each other for many years. Nowadays there are many commercial GPS based NTP time server products at the market but they almost have a high price. In this paper we are going to use a low cost GPS engine to build a time server to provide time synchronization with accuracy of a few milliseconds. This time server is relatively very cheap and it can be used in almost all typical applications. We also proposed a software based NTP time server implemented in MATLAB as well.
A. Abooee, M. R. Jahed Motlagh,
Volume 8, Issue 3 (9-2012)
Abstract
This paper focuses on the tracking and synchronization problems of hyperchaotic systems based on active backstepping method. The method consists of a recursive approach that interlaces the choice of a Lyapunov function with the design of feedback control. First, a nonlinear recursive active backstepping control vector is designed to track any desired trajectory in hyperchaotic Wang system. Furthermore, this method is applied to achieve hyperchaos synchronization of two identical hyperchaotic Wang systems. Also, it is used to implement global asymptotic synchronization between hyperchaotic Wang system and hyperchaotic Rössler system. Numerical simulations have been employed to verify the effectiveness of the three designed active backstepping control vectors.
M. Bakhshi, R. Noroozian, G. Gharehpetian,
Volume 9, Issue 2 (6-2013)
Abstract
Identification of intentional and unintentional islanding situations of dispersed generators (DGs) is one of the most important protection concerns in power systems. Considering safety and reliability problems of distribution networks, an exact diagnosis index is required to discriminate the loss of the main network from the existing parallel operation. Hence, this paper introduces a new islanding detection method for synchronous machine–based DGs. This method uses the average value of the generator frequency to calculate a new detection index. The proposed method is an effective supplement of the over/under frequency protection (OFP/UFP) system. The analytical equations and simulation results are used to assess the performance of the proposed method under various scenarios such as different types of faults, load changes and capacitor bank switching. To show the effectiveness of the proposed method, it is compared with the performance of both ROCOF and ROCOFOP methods.
A. Darabi, M. Yousefisefat, M. Nikkhoo,
Volume 10, Issue 1 (3-2014)
Abstract
Quadrature-axis reactance for various reasons comes into account as one of the most important parameters of salient pole synchronous machine. There are several common standard methods for measuring this parameter that also have been explained with some details in the standards, scientific papers and text books. One of these methods is the maximum lagging current test that is done simply at no-load, having a three phase voltage source and applying very low power even for a high power machine. How this experiment is done is described at some references such as the books related to electrical machinery. This paper presents a detail analysis and description of the test and some simulation results regarding the performance of the machine during pole-slipping. It is shown when the reversal field current is increased very slowly, the transient of the pole-slipping commences at load angle equal to 45 degrees or by a better language at 225 instead of zero which is the common opinion of almost all the previously published literatures. In this paper, a realistically developed analysis of the test is presented applying appropriate assumptions. The maximum lagging current test is then simulated applying a small salient pole machine with the rated 31.5 kVA using Matlab/Simulink. Some simulation results are illustrated that prove correctness and validity of the new analysis and the proof described by the present paper.
Z. Gallehdari, M. Dehghani, S. K. Nikravesh,
Volume 10, Issue 2 (6-2014)
Abstract
The purpose of this paper is to present a new approach based on the Least Squares Error method for estimating the unknown parameters of the nonlinear 3rd order synchronous generator model. The proposed method uses the mathematical relationships between the machine parameters and on-line input/output measurements to estimate the parameters of the nonlinear state space model. The field voltage is considered as the input and the rotor angle and the active power are considered as the generator outputs. In fact, the third order nonlinear state space model is converted to only two linear regression equations. Then, easy-implemented regression equations are used to estimate the unknown parameters of the nonlinear model.
The suggested approach is evaluated for a sample synchronous machine model. Estimated parameters are tested for different inputs at different operating conditions. The effect of noise is also considered in this study. Simulation results show that the proposed approach provides good accuracy for parameter estimation.
H. Fallah Khoshkar, A. Doroudi, M. Mohebbi,
Volume 10, Issue 4 (12-2014)
Abstract
This paper studies the effects of symmetrical voltage sags on the operational characteristics of a Permanent Magnet Synchronous Motor (PMSM) by Finite Element Method (FEM). Voltage sags may cause high torque pulsations which can damage the shaft or equipment connected to the motor. By recognizing the critical voltage sags, sags that produce hazardous torque variations could be prevented. Simulations results will be provided and the critical voltage sags are recognized. A simple theoretical analysis will also be presented to obtain a qualitative understanding of the phenomena occurring in PMSM during symmetrical voltage sags
A. Darijani, A. Kiyoumarsi, H. A. Lari, B. Mirzaeian Dehkordi, Sh. Bekhrad, S. Rahimi Monjezi,
Volume 11, Issue 1 (3-2015)
Abstract
Permanent-Magnet Synchronous Generators (PMSGs) exhibit high efficiency and power density, and have already been employed in gearless wind turbines. In the gearless wind turbines, due to the removal of the gearbox, the cogging torque is an important issue. Therefore, in this paper, at first, design of a Permanent-Magnet Synchronous Generator for a 2MW gearless horizontal-axis wind turbine, according to torque-speed and capability curves, is presented. For estimation of cogging torque in PMSGs, an analytical method is used. Performance and accuracy of this method is compared with the results of Finite Element Method (FEM). Considering the effect of dominant design parameters, cogging torque is efficiently reduced.
M. Alizadeh Moghadam, R. Noroozian, S. Jalilzadeh,
Volume 11, Issue 3 (9-2015)
Abstract
This paper presents modeling, simulation and control of matrix converter (MC) for variable speed wind turbine (VSWT) system including permanent magnet synchronous generator (PMSG). At a given wind velocity, the power available from a wind turbine is a function of its shaft speed. In order to track maximum power, the MC adjusts the PMSG shaft speed.The proposed control system allowing independent control maximum power point tracking (MPPT) of generator side and regulate reactive power of grid side for the operation of the VSWT system. The MPPT is implemented by a new control system. This control system is based on control of zero d-axis current (ZDC). The ZDC control can be realized by transfer the three-phase stator current in the stationary reference frame into d-and q-axis components in the synchronous reference frame. Also this paper is presented, a novel control strategy to regulate the reactive power supplied by a variable speed wind energy conversion system. This control strategy is based on voltage oriented control (VOC). The simulation results based on Simulink/Matlab software show that the controllers can extract maximum power and regulate reactive power under varying wind velocities.
H. Yaghobi, H. Kafash Haghparast,
Volume 11, Issue 3 (9-2015)
Abstract
Synchronous generators are of two type’s salient pole type and round rotor type. The load angle curve of a cylindrical rotor synchronous machine comprises a single sine term only while in salient pole synchronous generators, power-angle characteristic has two terms. The first term is the fundamental component due to field excitation (the same as the cylindrical rotor) and the second term includes the effect of salient pole. In fact, this term is the second harmonic component due to reluctance torque. This paper presents a study on the new design of cylindrical solid rotor synchronous generator. In this new design, rotor of the machine is designed in such a way that the required inductance values are reached to produce reluctance torque, besides electromagnetic torque due to field excitation. In this contribution, a combination of two different ferromagnetic materials is considered in the design of the rotor. In this theory, the tight connection between the different materials is very important from a mechanical point of view. In other words, this new idea and production principal has potential in some areas after some further research and engineering. But this paper is focused on magnetic flux-carrying materials and presents a study of the new design of cylindrical solid rotor synchronous generator (NCG). Then a comparative analysis was made between this new (NCG) and conventional cylindrical solid rotor synchronous generator (CCG) and the effectiveness of the new cylindrical solid rotor from a magnetic point of view is demonstrated. In this paper, mechanical and thermal aspects of design such as vibration did not analyze.
S. Ahmadi, A. Vahedi,
Volume 11, Issue 3 (9-2015)
Abstract
In this paper a multiobjective optimal design method of interior permanent magnet synchronous motor ( IPMSM) for traction applications so as to maximize average torque and to minimize torque ripple has been presented. Based on train motion equations and physical properties of train, desired specifications such as steady state speed, rated output power, acceleration time and rated speed of traction motor are related to each other. By considering the same output power, steady state speed, rated voltage, rated current and different acceleration time for a specified train, multiobjective optimal design has been performed by Broyden–Fletcher–Goldfarb–Shanno (BFGS) method and finite element method (FEM) has been chosen as an analysis tool. BFGS method is one of Quasi Newton methods and is counted in classic approaches. Classic optimization methods are appropriate when FEM is applied as an analysis tool and objective function isn’t expressed in closed form in terms of optimization variables.
M. E. Moazzen, S. A. Gholamian, M. Jafari-Nokandi,
Volume 13, Issue 2 (6-2017)
Abstract
Permanent magnet synchronous generators (PMSG) have a huge potential for direct-drive wind power applications. Therefore, optimal design of these generators is necessary to maximize their efficiency and to reduce their manufacturing cost and total volume. In this paper, an optimal design of a six-phase 3.5 KW direct-drive PMSG to generate electricity for domestic needs is performed. The aim of optimal design is to reduce the manufacturing cost, losses and total volume of PMSG. To find the best design, single/multi-objective design optimization is carried out. Cuckoo optimization algorithm (COA) is adopted to solve the optimization problem. Comparison between the results of the single-objective and multi-objective models shows that simultaneous optimization of manufacturing cost, losses and total volume leads to more suitable design for PMSG. Finally, finite-element method (FEM) is employed to validate the optimal design, which show a good agreement between the theoretical work and simulation results.
