Online ISSN
1751-8679
Print ISSN
1751-8660
IET Electric Power Applications
Volume 6, Issue 9, November 2012
Volumes & issues:
Volume 6, Issue 9
November 2012
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- Author(s): A. Boglietti ; A. Cavagnino ; M. Lazzari ; S. Vaschetto
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 583 –592
- DOI: 10.1049/iet-epa.2012.0037
- Type: Article
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A methodology to design three-phase squirrel-cage induction motors is presented. The main aim of the study is the preliminary electromagnetic sizing of the machine, obtaining the machine overall dimensions (diameters, core axial length and rough stator and rotor shape) and a draft of the stator winding specifications (turn number and wire area). The procedure is based on a simple geometrical approach and self-consistent equations, without any use of empirical/corrective coefficients. In the proposed design tool, the machine geometrical dimensions are automatically computed starting from a few design specifications imposed by the user, such as rated voltage and torque and electric and magnetic material solicitations. In this study, the design procedures and algorithms are described step-by-step and, for each step, the used equations are reported in detail, in order to allow readers to develop own ‘do-it-yourself’ software for induction motor electromagnetic design. The authors developed this software in a Microsoft Excel electronic sheet using embedded Visual Basic for Applications. To prove the goodness and accuracy of the proposed design tool, a comparison with two commercial software for electrical machine design and analysis has been done and discussed. - Author(s): Y.Z. Xu ; R. Zhong ; L. Chen ; S.L. Lu
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 593 –603
- DOI: 10.1049/iet-epa.2012.0157
- Type: Article
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593
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A new analytical method is proposed to produce optimal turn-on and turn-off angles, based on a non-linear inductance model of low-inductance region for switched reluctance motor (SRM). The optimal turn-on angle is derived from the non-linear model and electrical equation of SRM instead of the linear model while optimal turn-off angle is derived from the turn-on angle and flux-linkage. Considering the back electromotive force, the proposed method has more accuracy than the conventional analytical method and improves the efficiencies both at low speed and high speed. Simulation and experimental results demonstrate the validity and effectiveness of the proposed method, which is suited for low- and high-speed conditions both. - Author(s): Q. Li ; X. Wang ; L. Zhang ; J. Lou ; L. Zou
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 604 –610
- DOI: 10.1049/iet-epa.2012.0144
- Type: Article
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604
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A mathematical model for vibration analysis of the transformer core is developed in this study. Core vibration is principally caused by magnetostriction effect which is also a function of magnetisation. A simplified magnetisation model is introduced and compared with the J–A model in term of accuracy for the magnetic intensity within ±2500 A/m. As the magnetic properties are normally coupled with mechanical dependencies, the magnetostrictive characteristics are analysed based on establishment of the relationship between the strain and the stress. According to macroscopic thermodynamics and the law of energy conservation, a new model for magnetostriction effect is presented by expanding the Gibbs-free energy density in a polynomial form. In the cases where the magnetic field does not reach saturation, the quartic term and its above are neglected. The accuracy of the proposed magnetostrictive model is verified by comparing with the Sablik model. A mathematical expression for the equivalent magnetostrictive force is then derived, which is further utilised to calculate the core vibrations in the sinusoidal magnetic field. With the measurements previously available various numerical cases for core vibrations are evaluated and compared. - Author(s): A. Lalami ; R. Wamkeue ; I. Kamwa ; M. Saad ; J.J. Beaudoin
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 611 –620
- DOI: 10.1049/iet-epa.2012.0026
- Type: Article
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In a previous authors' work, a short circuit and start-up tests have been used with the so-called two steps identification method to compute the induction machine's (IM) electrical and mechanical parameters. This latter approach was unable to compute IM parameters with a single dynamic test and could not be applied when IM identification data are noise corrupted. In the present study, the unscented Kalman filter (UKF) is used as non-linear optimal predictor for the saturated electromechanical stochastic dynamic model of IM. In order to overcome the uncertainty on the knowledge of noise-model parameters, the maximum likelihood estimation algorithm is combined to the UKF to compute IM parameters. The technique is successfully applied for the parameters estimation of a 2-kW, 4-pole, 10-A, 60-Hz laboratory induction motor using a start-up test noisy corrupted data. Furthermore, a cross-validation of the estimated model using short-circuit test greatly attests to the effectiveness and validity of the estimated IM model in a wide range of applications. - Author(s): S. Tohidi ; M.R. Zolghadri ; H. Oraee ; P. Tavner ; E. Abdi ; T. Logan
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 621 –627
- DOI: 10.1049/iet-epa.2012.0101
- Type: Article
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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 synchronism is considered, where the asynchronous, double-cascade mode must be introduced to describe the machine performance. Second, a voltage dip at the mains terminal is considered. The simplistic behaviour of the BDFM during this fault, including the operation of a converter protective crowbar, is investigated using steady-state torque–speed curves to obtain a general view of the machine performance. - Author(s): A. Rahideh and T. Korakianitis
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 628 –638
- DOI: 10.1049/iet-epa.2011.0385
- Type: Article
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p.
628
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Two-dimensional analytical armature field calculations are presented for slotless permanent magnet brushless motors. The proposed method is applicable to both brushless AC and DC motors with any number of phases. The problem is formulated for eight annular regions: shaft, rotor back-iron, magnets, retaining sleeve, airspace, winding, stator back-iron and exterior. A general armature current density distribution is expressed as a function of spatial angle and time for any number of phases, any current waveform and any winding distribution. The governing partial differential equations of all the regions subject to a set of boundary conditions are represented and solved analytically for both internal and external rotor motors. Self- and mutual-inductance calculations as well as expressions for the calculation of rotor eddy current losses in the magnets, retaining sleeve and rotor back-iron are also represented. In the second part of these two papers, the open-circuit magnetic field is presented for different magnetisation patterns and subsequently the electromagnetic torque is calculated. The effectiveness of the analytical model is validated by comparing the results with those obtained from finite-element analyses as well as an experimental set-up which presented in the second part of the series. - Author(s): A. Rahideh and T. Korakianitis
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 639 –651
- DOI: 10.1049/iet-epa.2011.0386
- Type: Article
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This study presents the open-circuit analytical magnetic field distribution of slotless brushless permanent magnet motors equipped with surface-mounted magnets. Although the focus of the study is on open-circuit magnetic field analysis, by augmenting the open-circuit magnetic field distribution with the armature reaction field distribution obtained from the first part of the series of two studies, the electromagnetic torque is calculated. The electromagnetic torque is calculated for both internal and external rotor motors with six different magnetisation patterns and three different armature current waveforms. The analysis domain consists of eight annular concentric regions: motor shaft, rotor back-iron, magnets, retaining sleeve, air-gap, winding, stator back-iron and exterior regions. Based on the open-circuit magnetic field distribution, the induced back-electromotive force (EMF) is also calculated. The validity of the proposed model is confirmed by comparing the analytical results with those obtained from the finite element method and an experimental set-up. - Author(s): G. Shiny and M.R. Baiju
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 652 –660
- DOI: 10.1049/iet-epa.2012.0111
- Type: Article
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In this study, a space vector-based pulse width modulation scheme for an inverter with even number of levels is proposed. An approach based on fractal theory which utilises the self-similarity of the triangular sectors is employed in the present work, to find the sector and the inverter switching vectors. The space vector locations and associated computations are performed in a 60° coordinate system. Representation in a 60° framework avoids fractional arithmetic, thereby reducing computational complexity compared with the methods based on a Cartesian coordinate system. The duration of the switching vectors is determined after mapping the instantaneous reference space vector to an equivalent two-level inverter. The scheme is experimentally verified by using a four-level inverter configuration. four-level inversion is achieved with a dual inverter fed induction motor in the open-end winding configuration. The individual inverters are supplied with asymmetric DC link voltages. The switching vectors for the two inverters are automatically generated without using look-up tables. The scheme is implemented and tested with a 2-HP open-end winding induction motor drive. - Author(s): S. Sharif ; J. Faiz ; K. Sharif
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 661 –668
- DOI: 10.1049/iet-epa.2012.0006
- Type: Article
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p.
661
–668
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Skin effect and armature reaction are the two major factors that effectively influence the performance of eddy current brake. Although many analytical solutions consider the armature reaction, skin effect has a significant impact on the torque-speed characteristics of the brake as the most important performance factor. This study presents an analytical equation for the torque-speed characteristics of an eddy current brake with cylindrical rotor taking into account both skin effect and armature reaction. This equation is valid over a wide range of speeds, therefore critical speed and maximum torque of the brake can be computed precisely. The presented model is sufficiently fast, accurate and flexible for design of a cylindrical eddy current brake. The predicted results are validated by the experimental results. - Author(s): Y. Wang and Z. Deng
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 669 –680
- DOI: 10.1049/iet-epa.2012.0041
- Type: Article
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p.
669
–680
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The parallel hybrid excitation machines (PHEM), which exhibit good flux regulation capability and wide constant power operating capability, can not only reduce the coupling of the PM flux and electrical excitation flux but also avoid demagnetisation that occurs in the series hybrid excitation machines. This study compares and analyses the electromagnetic performance of different PHEMs with emphasis on the excitation source location, structures, operation principles, reliability and axial utilisation. Then, their control schemes for voltage regulation of DC generation systems are analysed based on different critical control variables including the excitation current, the armature current, the electromagnetic torque and the applications are also discussed. Furthermore, an improved direct torque control (DTC) scheme is investigated to improve the system performance. A parallel hybrid excitation flux-switching generator employing the improved DTC, which shows excellent dynamic and steady-state performance has been achieved experimentally. - Author(s): R.P. Vieira ; C.C. Gastaldini ; R.Z. Azzolin ; H.A. Gründling
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 681 –688
- DOI: 10.1049/iet-epa.2011.0269
- Type: Article
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681
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This study investigates the rotor speed estimation problem for induction motor drives. The authors propose the design of a scheme based on a discrete-time sliding mode observer which provides the rotor speed estimative. A new algorithm for discrete-time rotor speed estimation is developed and analysed. The conditions for the existence of a discrete-time sliding switching hyperplane are analysed. Moreover, conventional algorithms aiming at the chattering reduction and high-frequency switching on discrete-time implementation are discussed for use with the proposed technique. The stability analysis and parameter convergence of the proposed method are investigated for discrete-time solution. The algorithms developed are tested by experimental results based on fixed-point digital signal processor (DSP) platform (TMS320F2812). Therefore the results demonstrate the good performance of the proposed scheme. - Author(s): A.P.S. Baghel and S.V. Kulkarni
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 689 –695
- DOI: 10.1049/iet-epa.2011.0249
- Type: Article
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The modelling of magnetic components of electromagnetic devices requires an accurate representation of hysteresis characteristics of their material. This study proposes a hybrid technique to solve the parameter identification problem of the Jiles–Atherton hysteresis model. The technique leads to a considerable reduction in computations and gives efficient solution. The technique combines two different optimisation techniques in an effective way. An improvement in the convergence rate of the least-square method has been obtained by using a scaled gradient via the Hessian matrix. The results are validated using experimental data obtained by an Epstein's frame. - Author(s): A. Susperregui ; M.I. Martinez ; I. Zubia ; G. Tapia
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 696 –706
- DOI: 10.1049/iet-epa.2011.0358
- Type: Article
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p.
696
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A pulse-width modulation-based second-order sliding-mode control (2-SMC) scheme for the rotor-side converter feeding a doubly fed induction generator (DFIG) is presented. It is aimed at achieving both high robustness to DFIG parameter variations and close tracking of a predefined rotor speed-dependent optimum power curve, while preserving a fixed switching frequency. In addition, it eludes the appearance of chatter. Tuning equations are also derived to adjust all its gains and constants. The proposed 2-SMC algorithm is evaluated as part of a sensorless scheme on the mathematical model of a 660-kW DFIG via numerical simulation. Its operation in terms of robustness and dynamic performance is then compared with that of a classical PI-based vector control (VC) strategy. The validity of the suggested 2-SMC scheme, as well as its superior performance in comparison with its PI-based VC counterpart, are corroborated through experimentation carried out on a 7-kW DFIG test bench. - Author(s): W.X. Zhao ; M. Cheng ; K.T. Chau ; C.C. Chan
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 707 –715
- DOI: 10.1049/iet-epa.2011.0144
- Type: Article
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This study investigates the operations of a recently developed fault-tolerant flux-switching permanent-magnet (FT-FSPM) brushless motor, in which the concentrated coils of each stator phase are wound on alternate teeth and permanent-magnets (PMs) are located in the stator, offering a number of significant advantages over conventional PM brushless machines, such as simpler rotor structure, easier cooling in PMs and independence of phases. The control strategy of the FT-FSPM motor is proposed for torque ripple minimisation, in which the key is to introduce harmonic currents to compensate for non-ideal sinusoidal back-electromotive force (EMF). Both simulation and experimental results confirm that the proposed control algorithms can reduce torque ripple and offer good dynamic performance under normal and fault conditions. Hence, it can be concluded that the developed motor drive system is suitable for applications where reliability, efficiency and power density are of importance in such applications as electric and hybrid electric vehicles. - Author(s): S.D. Wilson ; P. Stewart ; J. Stewart
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 716 –726
- DOI: 10.1049/iet-epa.2010.0232
- Type: Article
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Real-time thermal management of electrical machines relies on sufficiently accurate indicators of internal temperature. One indicator of temperature in a permanent-magnet synchronous motor is the stator winding resistance. This study applies two current injection techniques to a commercially produced permanent-magnet servomotor, which are applicable under load and cause minimal disturbance to the shaft torque. The current injection techniques applied here enable the temporary boosting of resistive voltage and consequent application to low-resistance, high-voltage machines. The effectiveness of the approach is demonstrated by tracking the change in winding temperature during a 2 h load cycle. - Author(s): R.A. Naghizadeh ; B. Vahidi ; S.H. Hosseinian
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 727 –734
- DOI: 10.1049/iet-epa.2012.0085
- Type: Article
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This study presents a novel approach for modelling inrush current transient in power transformers taking into account the hysteresis effect. Inverse Jiles–Atherton (JA) model is used to represent the hysteresis phenomenon in the magnetic core. The parameters of this model are optimally determined using inrush current measurements by shuffled frog-leaping algorithm (SFLA). Then, an adaptive technique to enhance the accuracy of the proposed model for simulation of inrush current in other possible conditions is proposed. The method is based on artificial neural network which is used for updating the inverse JA hysteresis model parameters in each hysteresis loop during a power frequency cycle. SFLA optimisation is used for accurate parameter determination from measured inrush currents in training stage. The measurements are performed on a single-phase power transformer and the results verify the performance of the proposed neuro-SFLA approach. - Author(s): D. Fodorean ; L. Idoumghar ; A. N'diaye ; D. Bouquain ; A. Miraoui
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 735 –742
- DOI: 10.1049/iet-epa.2011.0029
- Type: Article
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This study presents a novel simulated annealing (SA) algorithm for the optimisation of an electrical machine. Firstly, the proposed SA algorithm is validated on five standard benchmark mathematical functions. Furthermore, the SA algorithm will be employed for the optimisation of a brushless synchronous motor. The optimised topology of the motor will be analysed numerically and the results will be validated experimentally. The obtained performances show that the proposed SA algorithm outperforms other algorithms described in the scientific literature. - Author(s): A. Jassal ; H. Polinder ; J.A. Ferreira
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 743 –752
- DOI: 10.1049/iet-epa.2011.0335
- Type: Article
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Eddy current is a very important and intriguing phenomenon. A direct result of Lenz's law, it has been an integral part of research on electrical machines. The applications and associated research field of eddy currents are very widespread and virtually impossible to include in a singlestudy. Therefore this study tends to capture research trends in eddy-current loss analysis pertaining to the field of rotating electrical machines only. The research period taken up is from 1892 to 2010. The trends in research and application have been brought out. This study aims to serve as a reference guide to all those interested in the field of eddy-current loss analysis in electrical machines. - Author(s): C. Sahin ; A.E. Amac ; M. Karacor ; Ali Emadi
- Source: IET Electric Power Applications, Volume 6, Issue 9, p. 753 –760
- DOI: 10.1049/iet-epa.2011.0397
- Type: Article
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p.
753
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Switched reluctance machines (SRMs) are of great interest because of their simplicity, low-cost, reliability, robustness, fault-tolerance and extended-speed constant-power operation. However, conventional SRMs suffer from high torque ripples. There exist several methods, which have been proposed to reduce torque ripples. One of the proposed methods is to change the geometric structure of the machine. However, analysis of the state-of-the-art designs show that, despite achieving favourable results in applications, the moulding pins of the machines are normally neglected. A motor that gives positive results may get affected negatively by its random moulding during its manufacturing. In this paper, mitigation of torque ripples in short-pitched SRMs (SPSRMs) and fully-pitched SRMs (FPSRMs) are investigated. Three-phase SPSRM and FPSRM are chosen for this study and the effects of the geometric points of moulding pins in the machines are studied comparatively. Maxwell 2D program is used for the analysis and two different models are compared for both SPSRM and FPSRM. The obtained results show that the torque ripples of the two machines are lower when moulding pins are closer to the rotor position. It is reduced by 2.56% at 10 Amps in the proposed SPSRM and 12% at 6 Amps in the proposed FPSRM. It is also observed that the applied method is more effective in reducing torque ripples of FPSRMs than SPSRMs.
Preliminary induction motor electromagnetic sizing based on a geometrical approach
Analytical method to optimise turn-on angle and turn-off angle for switched reluctance motor drives
Modelling methodology for transformer core vibrations based on the magnetostrictive properties
Unscented Kalman filter for non-linear estimation of induction machine parameters
Performance of the brushless doubly-fed machine under normal and fault conditions
Analytical magnetic field distribution of slotless brushless permanent magnet motors – Part I. Armature reaction field, inductance and rotor eddy current loss calculations
Analytical magnetic field distribution of slotless brushless PM motors. Part 2: Open-circuit field and torque calculations
Fractal-based low computation space phasor generation scheme for a four-level inverter using an open-end winding induction motor
Performance analysis of a cylindrical eddy current brake
Parallel hybrid excitation machines and their control schemes for DC generation system
Discrete-time sliding mode speed observer for sensorless control of induction motor drives
Parameter identification of the Jiles–Atherton hysteresis model using a hybrid technique
Design and tuning of fixed-switching-frequency second-order sliding-mode controller for doubly fed induction generator power control
Control and operation of fault-tolerant flux-switching permanent-magnet motor drive with second harmonic current injection
Real-time thermal management of permanent magnet synchronous motors by resistance estimation
Modelling of inrush current in transformers using inverse Jiles–Atherton hysteresis model with a Neuro-shuffled frog-leaping algorithm approach
Simulated annealing algorithm for the optimisation of an electrical machine
Literature survey of eddy-current loss analysis in rotating electrical machines
Reducing torque ripple of switched reluctance machines by relocation of rotor moulding clinches
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