Electrical Machines

Social media is a popular network through which user can share their reviews about various topics, news, products etc. People use internet to access or update reviews so it is necessary to express opinion. Sentiment analysis is to classify these reviews based on its opinion as either positive or negative category. First we have preprocessed the dataset to convert unstructured reviews into structured form. Then we have used lexicon based approach to convert structured review into numerical score value. In lexicon based approach we have preprocessed dataset using feature selection and semantic analysis. Stop word removal, stemming, POS tagging and calculating sentiment score with help of SentiWordNet dictionary have been done in preprocessing part. Then we have applied classification algorithm to classify opinion as either positive or negative. Support vector machine algorithm is used to classify reviews where RBF kernel SVM is modified by its hyper parameters which are soft margin constant C , Gamma γ. So optimized SVM gives good result than SVM and naïve bayes. At last we have compared performance of all classifier with respect to accuracy.

Increasing competition in the global transformer market has put tremendous responsibilities on the industry to increase reliability while reducing cost. Spotlight on Modern Transformer Design introduces a novel approach to transformer design using artificial intelligence (AI) techniques in combination with finite element method (FEM). Today, AI is widely used for modeling nonlinear and large-scale systems, especially when explicit mathematical models are difficult to obtain or completely lacking. Moreover, AI is computationally efficient in solving hard optimization problems. On the other hand, FEM is particularly capable of dealing with complex geometries, and also yields stable and accurate solutions.

Many numerical examples throughout the book illustrate the application of the techniques discussed to a variety of real-life transformer design problems.

Spotlight on Modern Transformer Design is a valuable learning tool for advanced undergraduate and graduate students, as well as researchers and power engineering professionals working in electric utilities and industries, public authorities, and design offices.

In this paper, we present a new contribution for the control of Wind-turbine energy systems, a nonlinear
robust control of active and reactive power by the use of the Adaptative Backstepping approach based in
double-fed asynchronous generator (DFIG-Generator).
Initially, a control strategy of the MPPT for extraction of maximum power of the turbine generator is
presented. Thereafter, a new control technique for wind systems is presented. This control system is
based on an adaptive pole placement control approach integrated to a Backstepping control system. The
stability of the system is shown using Lyapunov technique. Using the FPGA to implement the order gives
us a better rapidity. A Benchmark was realized by a prototyping platform based on DFIG-generator, FPGA
and wind-turbine; the experimental results obtained show the effectiveness and the benefit of our
contribution.

The losses in European Union distribution transformers are estimated at about 33 TW · h/year, whereas reactive power and harmonic losses add a further 5 TW · h/year. The reduction of distribution transformer no-load loss is particularly important as the ratio of no-load to load losses is nearly three. In this paper, the no load operation of wound-core transformers under sinusoidal and distorted supply-voltage conditions is investigated. For that purpose, a 2-D nonlinear transient finite-element analysis taking into account hysteresis has been developed. The hysteresis model is based on a modified Jiles–Atherton representation, and the proposed analysis is compared to experimental data.

In this paper, an optimal solution to the harmonic reduction problem in a cascaded multilevel inverter with nonequal DC sources using genetic algorithm (GA) is presented. Switching angles are generated for different values of modulation index by proposed algorithm, considering minimum voltage total harmonic distortion (THD) whereas selected harmonics are controlled within the allowable limits at all desired modulation indices including the point of discontinuity. Results are stored as a look-up table to be used to control the inverter for certain operating point. The computed angles are used in simulated circuit in Matlab\Simulink to validate the results.

The aim of the transformer design is to completely obtain the dimensions of all the parts of the transformer based on the given specification, using available materials economically in order to achieve lower cost, lower weight, reduced size and better operating performance. In this paper, a transformer design optimization method is proposed aiming at designing the transformer so as to meet the specification with the minimum cost. Results from the application of the proposed methodology demonstrate the effectiveness and practicality of this approach.

This paper compares the performance of two different control techniques applied to high performance brushless DC motor. The first scheme is self-tuning fuzzy PID controller and the second scheme is model reference adaptive control (MRAC) with PID compensator. The purpose of the control algorithm was to force the rotor speed to follow the desired reference speed with good accuracy all time. This objective should be achieved for different speed/time tracks regardless of load disturbance and parameter variations. The simulation results presented show that the second control scheme has better performance. Ó 2016 Faculty of Engineering, Ain Shams University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

This paper addresses the complex optimum transformer design problem, which is formulated as a mixed-integer nonlinear programming problem, by introducing an integrated design optimization method based on evolutionary algorithms and numerical electromagnetic and thermal field computations. The main contributions of this research are: i) introduction of a new overall transformer optimization method, minimizing either the overall transformer materials cost or the overall transformer materials and operating cost, ii) expansion of the solution space by innovative techniques that define the variation of crucial design variables such as the conductors' cross-section, ensuring global optimum transformer designs, and iii) incorporation of numerical field computation in order to validate the feasibility of the optimum designs. The proposed method is compared with a heuristic optimization method of the transformer manufacturing industry and the results demonstrate the robustness and the superiority of this new approach.

This paper concerns the thermal investigation of a surface-mounted permanent-magnet synchronous motor designed for high-temperature aerospace actuation applications. A finite-element package was developed, enabling accurate 3-D transient thermal analysis by considering complex and unsymmetrical actuator housing configurations. Its validity was verified by measurements carried out at different duty cycles and operating conditions.

This paper presents a novel topology for a nonisolated bidirectional dc-dc converter with soft-switching capabilities, which usually operates at a zero-voltage-switching (ZVS) condition. A nonisolated dc-dc converter combines a buck converter and a backward boost converter into one circuit, which consists of a half-bridge power switch, an inductor, and capacitors. In order to realize ZVS conditions, the proposed converter utilizes a coupled inductor, a small independent inductor, and auxiliary switches and diodes. Due to ZVS, switching stress on switch components is reduced, and the reverse recovery problem of MOSFET antiparallel body diodes is also eliminated. Moreover, the operating modes of the proposed converter can be switched between a ZVS mode and a conventional hard-switching mode on the basis of load conditions. The soft-switching mode is for heavy loads, and the hard-switching mode is for light-load conditions. Therefore, the highest efficiency can be obtained at almost all load ranges. The detailed theoretical analyses in each mode are presented, and a 1-kW prototype is also built to verify the principle of the circuit and the theoretical analysis.

We present an analytical solution for the magnetic field, induced eddy currents, and the corresponding losses generated in the rotor of a slotless permanent-magnet (PM) motor. The field excitation is a current sheet placed at the stator interior surface. The solution is based on an analytical solution of the diffusion equation using double Fourier series and in the complex domain. The first and the second Fourier series correspond to the time and space harmonics, respectively. We have analyzed the effect of each time harmonic in detail, and verified the results with FEM software.

Transformer design optimization is determined by minimizing the transformer cost taking into consideration constraints imposed both by international specifications and customer needs. The main purpose of this work is the development and validation of an optimization technique based on a parallel mixed integer nonlinear programming methodology in conjunction with the finite element method, in order to reach a global optimum design of wound core power transformers. The proposed optimization methodology has been implemented into software able to provide a global feasible solution for every given set of initial values for the design variables, rendering it suitable for application in the industrial transformer design environment.

The transformer manufacturing cost minimisation (TMCM), also known as transformer design optimisation, is a complex constrained mixed-integer non-linear programming problem with discontinuous objective function. This paper proposes an innovative method combining genetic algorithm (GA) and finite element method (FEM) for the solution of TMCM problem. The main contributions of the proposed method are: (a) introduction of an innovative recursive GA with a novel external elitism strategy associated with variable crossover and mutation rates resulting in an improved GA, (b) adoption of two particular finite element models of increased accuracy and high computational speed for the validation of the optimal design by computing the no-load loss and impedance and (c) combination of the innovative recursive GA with the two particular finite element models resulting in a proposed GA-FEM model that finds the global optimum, as concluded after several tests on actual transformer designs, while other existing methods provided suboptimal solutions that are 3.1 – 5.8% more expensive than the optimal solution.

This paper introduces a novel technique for iron loss minimization of wound core transformers. The proposed technique involves the evaluation of appropriate design variables of wound cores constructed by a combination of standard and high magnetization grade steel. The evaluation of the optimum design variables of the multiple grade lamination wound core is achieved by combining a permeability tensor finite-element model and simulated annealing with restarts.

Vibration-Based Condition Monitoring (VBCM) provides essential data to perform Condition-Based Maintenance for efficient, optimal, reliable, and safe industrial machinery operation. However, equipment required to perform VBCM is often relatively expensive. In this paper, a low-cost vibration measurement system based on a microcontroller platform is presented. The FRDM K64F development board was selected as the most suitable for fulfilling the system requirements. The industrial environment is highly contaminated by noise (electromagnetic, combustion, airborne, sound borne, and mechanical noise). Developing a proper antialiasing filter to reduce industrial noise is a real challenge. In order to validate the developed system, evaluations of frequency response and phase noise were carried out. Additionally, vibration measurements were recorded in the industry under different running conditions and machine configurations. Data were collected simultaneously using a standard reference system and the low-cost vibration measurement system. Results were processed using Fast Fourier Transform and Welch's method. Finally, a low-cost vibration measurement system was successfully created. The validation process demonstrates the robustness, reliability, and accuracy of this research approach. Results confirm a correlation between signal frequency spectrum obtained using both measurement systems. We also introduce new guidelines for practical data storage, communications, and validation process for vibration measurements.

In this paper, the influence of magnetic shunt geometry on the transformer leakage field and short-circuit impedance is examined. The magnetic-field computation is conducted with the use of a particular hybrid finite-element method (FEM) boundary-element method (BEM) formulation, facilitating the parametric investigation of magnetic shunt effects through application of appropriate boundary conditions. A design sensitivity analysis for the optimization of the shunt geometry ensuring a desired change in short-circuit impedance and shunt losses has also been developed, in conjunction with the magnetic-field model. Index Terms—Design optimization, finite-element (FEM) boundary-element (BEM) hybrid methods, sensitivity analysis, transformers.

This paper presents three different robust controller
techniques for high performance brushless DC (BLDC) motor.
The purpose is to test the ability of each control technique to force
the rotor to follow a preselected speed/position track. This
objective should be achieved regardless the parameter variations,
and external disturbances. The first technique is conventional PID
controller. The second controller technique use genetic algorithm
to adjust the PID controller parameters based on three different
cost functions. Finally a self-tuning fuzzy PID controller is
developed and tested. These controllers are tested for both speed
regulation and speed tracking. Results shows that the proposed
self-tuning fuzzy PID controller has better performance.

This article describes a detailed analytical method for obtaining the capacitance matrix elements in variable capacitance synchronous machines (VCSMs). The analytical modelling approach is performed by introducing a decentralized sinusoidal distribution of the stator/rotor electrodes and involves obtaining the capacitance matrix elements based on the electro motive force distribution in the air gap and calculating the induced electric charge in the stator/rotor electrode surfaces. The proposed analytical formulas are valid for both radial-field and axial-field VCSM structures. The analytical model is evaluated and well verified through analysing a multi-stack axial-field VCSM using 3D finite element simulation. Furthermore, a prototype of the VCSM is manufactured and tested to validate the results obtained from the proposed analytical model and finite element method simulations. Based on the results, the proposed model and analytical formulas are able to accurately estimate the capacitance matrix elements of the VCSMs.

As system investment and energy costs continue to increase, electric utilities are increasingly interested in installing energy-efficient transformers at their distribution networks. The cost evaluation of transformers is based on total owning cost (TOC) method that includes transformer purchasing price and cost of transformer losses. Similar to energy cost, greenhouse gas (GHG) emissions are also assigned a price by energy markets. That is why this study proposes an innovative distribution transformer cost evaluation methodology (DTCEM) by introducing the environmental cost (EC) into the conventional TOC method. This EC is due to GHG emissions associated with supplying transformer losses. The proposed method is applied for economic evaluation of distribution transformers for the Hellenic power system and the results are compared to the conventional TOC, indicating the importance of incorporating EC into transformer economic evaluation. A sensitivity analysis is carried out, investigating the impact of various parameters involved in the proposed DTCEM.

This paper shows experimental results of longitudinal flux density and its harmonics at the limb, the yoke and the corner of a three phase, Si-Fe, five-legged wound transformer core. Results show that the flux density is nonuniform in the cores and there is high level of third harmonic component. Moreover, the lower flux values in the outer cores have been assessed and the simultaneous time variation of the flux in both outer cores has been demonstrated by measurements while the peak magnetic flux density values have been compared to FEM analysis. These findings enable a better understanding of the magnetic behavior of five legged wound transformer cores and their consideration is expected to achieve respective improvement of the design with respect to core losses and magnetostriction noise.

This paper focuses on the design issues of a thermo-acoustically driven low-cost linear alternator for the SCORE project. SCORE (www.score.uk.com) aims to improve the quality of life around 2 billion poor people in the rural communities of the developing countries. The advantage of the double Halbach array permanent magnet moving coil alternator structure over traditional loudspeaker as a linear alternator is presented. The theoretical analysis of the linear alternator at different coil configurations with the rectifier circuit is explained and analysed with the finite elements simulation results. The simulation results show that the double coil structure with the smaller number of coil turns would be suitable for this project. The experimental results of the double Halbach array prototype which has been built and tested are discussed and compared with the simulation results.

This paper proposes finite element (FE) numerical methodologies for the transient heat transfer analysis of highly integrated actuators for demanding aerospace applications. A FE surface heat source is developed which permits to independently simulate the thermal performance of the housing of the actuator. As a result, the complexity of the FE model is reduced significantly and the computational cost is minimized. The proposed technique is integrated into a three dimensional (3–D) FE package that employs preprocessors capable of producing highly parameterized cooling housings of arbitrary configurations. The specific 3–D FE code was used for the transient heat transfer analysis of a surface mounted permanent magnet motor (PMM) and its non–standardized and unsymmetrical cooling housing.

1-The identification of optimal locations for 3 Static VAr Compensators (SVC's) in an IEEE 30 bus system is considered in this paper. The problem is drafted as an optimization task and the solution is achieved through Particle Swarm Optimization (PSO). Extensive simulation results are presented to validate the new approach.

Condition based maintenance (CBM) requires continuous monitoring of mechanical/electrical signals and various operating conditions of the machine to provide maintenance decisions. However, for expensive complex systems
(e.g. aerospace), inducing faults and capturing the intelligence about the system is not possible. This necessitates to have a small working model (SWM)
to learn about faults and capture the intelligence about the system, then scale up the fault models to monitor the condition of the complex/prototype system, without ever injecting faults in the prototype system. We refer to
this approach as scalable fault models. We check the effectiveness of the proposed approach using a 3 kVA synchronous generator as SWM and a 5 kVA synchronous generator as the prototype system. In this work, we identify and remove the system-dependent features using nuisance attribute projection (NAP) algorithm to model a
system-independent feature space to make the features robust across the two different capacity synchronous generators. The frequency domain statistical features are extracted from the current signals of the synchronous
generators. Classification and regression tree (CART) is used as a back-end classifier. NAP improves the performance of the baseline system by 2.05%, 5.94%, and 9.55% for the R, Y, and B phase faults respectively.

In this article, a finite element model, suitable for power transformer representation, is used for the evaluation of transformer characteristics and their modification due to the introduction of electric shielding, focusing on the short-circuit impedance calculation. The use of deterministic optimization methods, in conjunction with the finite element model enables the optimization of the transformer shielding geometrical configuration, with respect to its cost and efficiency.

Clean and sustainable alternative energy is becoming attractive as oil costs rise and the negative side effects of traditional energy systems begin to become apparent. One often overlooked, but still rapidly growing alternative is wave power. There are fascinating new designs for harnessing the tremendous power of the waves. Hence any contribution in this field could be of real interest for numerous specialists. In the paper a novel modular permanent magnet tubular linear generator is proposed and analyzed by means of numeric field computations. It was designed for wave power take off systems to be placed in the Black Sea near the Romanian coasts.

After the completion of core manufacturing and before the assembly of transformer active part, 2N small individual cores and 2N large individual cores are available and have to be optimally combined into N transformers so as to minimise the total no-load loss (NLL) of N transformers. This complex combinatorial optimisation problem is called transformer no-load loss reduction (TNLLR) problem. A new approach combining differential evolution (DE) and multilayer perceptrons (MLPs) to solve TNLLR problem is proposed. MLPs are used to predict NLL of wound core distribution transformers. An improved differential evolution (IDE) method is proposed for the solution of TNLLR problem. The modifications of IDE in comparison to the simple DE method are (i) the scaling factor F is varied randomly within some range, (ii) an auxiliary set is employed to enhance the population diversity, (iii) the newly generated trial vector is compared with the nearest parent and (iv) the simple feasibility rule is used to treat the constraints. Application results show that the performance of the proposed method is better than that of two other methods, that is, conventional grouping process and genetic algorithm. Moreover, the proposed method provides 7.3% reduction in the cost of transformer main materials.

This paper explores the design of an ultralight-weight power and torque dense motor to enhance the performance of a light-weight electric racing vehicle. Such a racing vehicle is to compete in formula student racing events. The state-of-the-art powertrain in these vehicles are axial-field machines or medium speed radial-field machines with a gear. This paper concerns a high speed traction machine radial-field design that closely considers the endurance duty-cycle and/or driving cycle of a race car and provides fast acceleration. The proposed electrical machine is designed to be ultra-light-weight. Therefore, an 18,000 rpm (single gear), 24 slot, 4 pole and 33 Nm brushless highly saturated permanent magnet machine is designed, with an active mass of around 3.0 kg (- 10kWlkg and 10 Nmlkg). To account for the various race events, the velocity of the racing tracks is to be closely matched with the machine output characteristics. Within this paper, the design and no-load results will be presented. In the near future (Q2 of 2015), following extended tests, this machine (integrated with a specifically designed single-stage gear) will be used to drive the vehicle using torque vectoring on all four-wheels. We expect that this will result in a significant performance gain in acceleration, endurance and handling characteristics of the 2015 University Racing Eindhoven race vehicle.

One of the still open issues within low-frequency magnetics is the inclusion of µ r in the calculations using the magnetic charge method. In this paper, a new iterative method to consider the relative permeability is investigated. This new method assumes a position-dependent surface charge distribution. Comparisons between model and finite element method results show that the model accurately accounts for the permeability of a magnet and a soft-magnet block within four iterations.

Switched reluctance motor (SRM) is an energy efficient machine, which receives electrical energy from the power source and returns part of the stored magnetic energy back to the supply, during each cycle of the machine operation. Characteristically, the SRM possesses nonlinear characteristics due to dual saliency and magnetic saturation. The exertion is realized in developing a mathematical model of the machine in presence of huge input data tables, famously, known as static characteristics. These data tables are required for mathematical modeling of the machine in a single pulse, steady state and transient performances separately. This paper presents a simple and flexible mathematical model of a switched reluctance machine in MATLAB/Simulink environment. In Simulink, based on graphical coding environment, the proposed model uses fewer data tables and less simulation time. Furthermore, with less addition to the same proposed model, another operating mode of the machine is possible, under the same operating conditions. A similar model in MATLAB, based on test code environment is also proposed, using the same operating conditions as in the Simulink based model to see the difference. The obtained results are validated by comparing the results of both the models, and with the experimentally obtained results, under single pulse, steady-state, and dynamic modes of the machine operation. The proposed model can handle the measured or computed data of the flux linkage and static torque, respectively.

A novel conversion structure for photovoltaic (PV) grid connection is proposed in this paper. The conversion system is aimed to be relatively simple and effective in medium and high power range. The topology utilizes a dual two-level voltage source inverter (VSI), fed by two insulated PV fields, supplying a grid transformer with open-end connection. Use of proposed scheme doubles the output power range of the conversion system with respect to the rated power of a single inverter, without the need of series/parallel connections of power switches. Furthermore, the dual inverter structure allows multilevel voltage waveforms, reducing grid current harmonics and mitigating output voltage derivatives.

Improvements in energy efficiency of electrical equipment reduce the greenhouse gas (GHG) emissions and contribute to the protection of the environment. Moreover, as system investment and energy costs continue to increase, electric utilities are increasingly interested in installing energy-efficient transformers at their distribution networks. This paper analyzes the impact of the environmental cost of transformer losses on the economic evaluation of distribution transformers. This environmental cost is coming form the cost to buy GHG emission credits because of the GHG emissions associated with supplying transformer losses throughout the transformer lifetime. Application results on the Hellenic power system for 21 transformer offers under 9 different scenarios indicate that the environmental cost of transformer losses can reach on average 34% and 8% of transformer purchasing price for high loss and medium loss transformers, respectively. That is why it is important to incorporate the environmental cost of transformer losses into the economic evaluation of distribution transformers.

This paper presents a hybrid cascaded H-bridge multilevel motor drive direct torque control (DTC) scheme for electric vehicles (EVs) or hybrid EVs. The control method is based on DTC operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a hybrid cascaded H-bridge multilevel inverter, where each phase of the inverter can be implemented using a dc source, which would be available from fuel cells, batteries, or ultracapacitors. This inverter provides nearly sinusoidal voltages with very low distortion, even without filtering, using fewer switching devices. In addition, the multilevel inverter can generate a high and fixed switching frequency output voltage with fewer switching losses, since only the small power cells of the inverter operate at a high switching rate. Therefore, a high performance and also efficient torque and flux controllers are obtained, enabling a DTC solution for multilevel-inverter-powered motor drives. Index Terms-Automotive application, direct torque control (DTC), induction motor, multilevel inverters. I. INTRODUCTION M ULTILEVEL voltage-source inverter topologies, including diode-clamped, flying capacitor, and cascaded H-bridge structures, are intensively studied for high-power applications [1]-[5], and standard drives for medium-voltage industrial applications have become available [6], [7]. Solutions with a higher number of output voltage levels have the ability to synthesize waveforms with a better harmonic spectrum and to limit the motor-winding insulation stress. However, their increasing number of devices tends to reduce the overall reliability and efficiency of the power converter.

A three-phase synchronous machine was, and still is, one of the most important element in today's power generation systems (operating as a generator) or in distribution– load systems (operating as a motor). Thus, a suitable and detailed model is required to be used by students and future engineers in order to deal with transient stability analyses. For this purpose, the paper presents and analyses a procedure by which the mathematical modelling of a three-phase, four-pole, synchronous machine can be implemented in the LabVIEW environment. A suitable graphics user interface is proposed and case studies under different machine operating conditions are shown. The corresponding results illustrate the validity and accuracy of the model. Furthermore, a reactive power PI controller is also implemented. The overall graphics user interface/ simulation model is applied to an undergraduate course as a teaching tool and assessed thoroughly. It is shown that the proposed tool may be utilized in under/post-graduate studies as well as in power utilities practician engineers courses.

The integrated starter-generator (ISG) replaces both the conventional starter and alternator (generator) of an automobile in a single electric device. It allows greater electrical generation capacity and the fuel economy and emissions benefits of hybrid electric automotive propulsion. The ISG requires contrary specifications, i.e. a high starting torque and a field-weakening capability in a wide speed range, therefore its design is a challenging job. In this paper the basic characteristics and some of the ISG variants will be discussed. Also a switched reluctance machine (SRM) based ISG prototype will be presented in detail.

The paper presents an accurate and cost effective three-dimensional finite element model for the analysis and design of wound core, shell type, power transformers, focusing on the short-circuit impedance evaluation. The model efficiency lies on the detailed representation of the transformer geometry along with the adoption of a particular reduced scalar potential formulation enabling three-dimensional magnetostatic problem solution without prior source field calculation. Its accuracy is validated through local field measurements and through comparison of the calculated short-circuit impedance value with the measured one for several commercial wound core, shell type transformers. In such transformers, involving extensive winding parts out of the core window, the detailed representation of the transformer geometry, including the winding cooling ducts, provides accurate results for low densities of the three-dimensional finite element mesh, resulting to reduction of the required calculation time. The model is used in the development of a computational tool, which enables the automated and accurate transformer characteristics prediction, adopted to the manufacturing process. This tool has also been applied in the impedance calculation for different winding connections of dual voltage transformers, thus providing the information needed for the achievement of an accurate design and the enhancement of the manufacturer's ability to reduce design margins. The methodology presented in this paper has been incorporated in the design process of a transformer manufacturing industry.

This paper is concerned with the analytical calculation of the interaction force between two permanent magnets (PMs) under relative rotation by means of the surface charge method, taking into account the non-unity relative permeability of the PMs. This model combines high accuracy and a short calculation time. As the considered PM configuration is a free-space, unbounded problem, the results from the surface charge method are compared to its numerical counterpart, the Boundary Element Method (BEM). The analytical expressions were validated by means of the measurement results obtained from a 3-D printed test setup.

In this paper a new flux-switching permanent magnet (FSPM) machine with 12 stator poles and 14 rotor poles is investigated, and compared to a machine with the same stator but 10 rotor poles. Two prototypes are studied by both finite element method (FEM) analysis and experimental measurements. The results show that the 12/14 pole prototype can provide about 7-12% higher torque, the torque ripple reduces from 8.5% to 5.1% and its synchronous inductance is also 15% higher. After optimization, the FEM simulation results show the 12/14 pole machine could provide 19% higher torque than the 12/10 pole machine and the torque ripple is further reduced to 2.3%.

Nowadays, advanced applications of motion control often require a coordinated management of several mechanical degrees-of-freedom (DoF). This is conventionally achieved by using suitable mechanical devices and a separate actuator per each DoF. Electric actuators able to directly manage multiple DoF may provide appreciable benefits in terms of performances, volume, weight and cost. This paper aims to provide an overview of several configurations of multi-DoF electromechanical actuators considered in the recent technical literature and presently under study.

A brushless doubly fed machine is equipped with two decoupled windings on its stator, known as the power winding and the control winding. The power winding reactive power can be controlled by voltage amplitude fed by the machine-side converter to the control winding, affecting both the converter size and machine efficiency. This paper investigates different proposed scenarios for optimal reactive power flow targeted to minimize the converter cost and maximize the machine efficiency. Previously, the grid-side converter has not been used for reactive power compensation. However, in the present paper it is shown how the grid-side converter can be effectively used to reduce the converter cost by controlling the flow of reactive power. The optimal power winding reactive powers for minimizing the converter cost and for maximizing the output power are not the same. Then the priority of minimizing converter cost over maximizing machine output power has been justified.

—The design method of initial topology of interior permanent magnet synchronous machine (IPMSM) for hybrid electric vehicle (HEV) propulsion is described in this paper. Design constraints are selected on the basis of limitations imposed by machine's manufacturer and application (e.g. maximum copper slot fill factor, air gap length, permanent magnet material, limited space available in drive trains, etc.). Design variables are rotor radius, stator slot width and number of turns per phase winding. Parametric analysis is performed for various machine topologies. The cost function, which connects the distribution of operating points of HEV and the efficiency maps of various topologies of an electrical machine, is defined. Obtained parametric results are compared to find the result leading to the extreme value of the cost function. The initial design of IPMSM that corresponds to this result is considered as the best initial design.