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In this study, a linear synchronous machine is compared with a linear transverse flux machine. Both machines have been designed and built with the intention of being used as the power take off in a free piston engine. As both topologies are cylindrical, it is not possible to construct either using just flat laminations and so alternative methods are described and demonstrated. Despite the difference in topology and specification, the machines are compared on a common base in terms of rated force and suitability for use as a generator. Experience gained during the manufacture of two prototypes is described. [ABSTRACT FROM AUTHOR]

This study discusses the topology development of a cylindrical transverse flux linear machine for use with a free piston engine. Despite its three-dimensional flux path, the stator of this topology can be made from regular laminated components and only the translator includes soft magnetic composites. The detailed design development is discussed, including stator tooth combination, alternative winding, and fabrication techniques. Results from both finite element analysis and experimental measurement are compared, which gives a validation of the feasibility of the building process. [ABSTRACT FROM AUTHOR]

The use of a winding step of two slots attempts to strike a balance between traditional distributed windings and fractional slot concentrated windings. It promises less ohmic losses and space for the end windings than distributed windings and less harmonics than fractional slot concentrated windings. This paper gives an introduction into the design of windings with a winding step of two slots for six-phase machines. The design procedure relies on the star of slots. Whereas for a given combination of slots and poles, the winding of a three-phase machine is unique, there exist several winding designs for six-phase machines. They differ by the shape of the phase belts and by the phase shift between the two three-phase subsystems. The definition of two characteristic figures facilitates the comparison of these windings: one describes the content of sub-harmonics in the magnetomotive force, the other is a measure for rotor eddy losses. The comparison reveals that windings with 12 small phase belts are better as long as fault tolerance is not an issue. If this is the case, windings with wider phase belts and a proper choice of pole number and phase shift are superior. [ABSTRACT FROM AUTHOR]

A series of systematic studies are carried out to investigate the influence on torque density and power density on machine speed rating. Several series of permanent magnet machine designs are established using an array of different electrical and thermal design constraints. The paper demonstrates that torque density in permanent magnet machines tends to decrease with speed rating due to complex interplay between electromagnetic and mechanical considerations, e.g. fixed winding current density, fixed split ratio etc. Interesting trends are observed, including cases in which there is an optimum rotational speed in terms of power density, beyond which the power density starts to decrease with increased speed rating. [ABSTRACT FROM AUTHOR]

Here, the selection of optimal slot/pole (Ns-slot/pr-pole) number combination between the pairs of fractional slot concentrated winding (FSCW) permanent magnet synchronous machines (PMSMs) with Ns = 2pr ± 1 or Ns = 2pr ± 2 will be analysed by a modified winding function accounting for slot opening and validated by finite element method. The results show that for FSCW PMSMs with Ns = 2pr ± 1 or Ns = 2pr ± 2, the higher pole machine will have larger winding factor and hence better torque performance than the lower pole one. Moreover, it also reveals that this torque advantage is more evident in the external rotor machine than that in internal rotor machine. [ABSTRACT FROM AUTHOR]

This paper proposes some consequent-pole (CP) modular permanent magnet (PM) machines with different flux gap (FG) widths and slot/pole number combinations. The corresponding inset modular PM machines having the same magnet volume are also presented for comparison. It has been demonstrated that the output torques of the consequent pole modular machines are always higher than those of the inset modular machines regardless of FG widths and slot/pole number combinations. Other electromagnetic performances such as back-EMF, cogging torque, and iron losses etc. are calculated by 2D FEA software and compared as well. The advantages and disadvantages of consequent and inset modular PM machines are summarised here. [ABSTRACT FROM AUTHOR]

Here, the influence of stator slot and rotor pole combination on performance of flux reversal permanent magnet (FRPM) machine with consequent-pole permanent magnet (CPM) structure is analysed. First, for 12-slot FRPM machines, the torque capabilities of CPM and conventional surface-mounted PM (SPM) structure having different rotor poles are compared. It shows that the torques of CPM machines are largely affected by the rotor pole number while the torques of SPM machines are similar. This is further explained by the equivalent pole-pair number and corresponding saturation condition. The influence of stator slot number and PM width ratio on torque performance of the CPM-FRPM machine is then investigated. Finally, detailed electromagnetic performance of the 12/14 SPM- and CPMFRPM machine is analysed and compared. [ABSTRACT FROM AUTHOR]

To effectively find a valid solution in the development process of electrical machines, it is essential to predict machine iron loss in the pre-design stage. In guidance on the choice of the most suitable configuration of the switched reluctance machine (SRM) is given, but iron loss prediction is neglected. Based on the study of Burkhart et al., this study proposes a simplified model to efficiently calculate iron loss in the design procedure of SRMs. For this purpose, a maximum co-energy loop control method is implemented to facilitate the estimation of flux waveform and machine torque. Three different iron loss calculation methods are compared in terms of accuracy and time. The accuracy of the simplified model is verified by comparison with finite element simulation results. Furthermore, the impact of different parameters on the iron loss is discussed, and the iron loss of various machine geometries is comparatively analysed. [ABSTRACT FROM AUTHOR]

This study presents the design and analysis of the segmented rotor design for an electrical machine embedded onto the more electric aircraft gas turbine engine shaft. The high-speed operational environment imposes high stress levels due to centrifugal forces; thus, the feasibility of this segmented rotor topology for such application is explored and a suitable design is proposed to overcome mechanical stresses. Finite element structural analysis was performed to compare the mechanical behaviour of a different rotor segment fixing structure and the proposed design. Also, electromagnetic analysis is carried out on a high-speed switched reluctance machine to study the impact of a new design on machine electromagnetic performance. [ABSTRACT FROM AUTHOR]

This study introduces the development of the straight pole four-phase double-stator switched reluctance machine (SRM) which is considered to provide high torque density and low copper loss. The basic concept behind this design is to combine the features of the mutually coupled SRM and the double-stator SRM. In this study, the analytical method alongside the 2D finite element method (FEM) verification would be presented to reveal the developing path. Moreover, to verify the proposed SRM concept, the prototype machine has been designed and built. The performance result from 2D FEM is presented. [ABSTRACT FROM AUTHOR]

Here, static and dynamic (rotating) misalignments between the low-speed rotor (LSR) and the stator of axial flux magnetically geared machines are studied with the aid of 3-D finite element analysis (FEA). The influence of rotor/stator axis misalignments on machine performance in terms of cogging torque, air-gap flux density, and back-EMF is investigated with reference to the fully healthy condition. The results show that the LSR and HSR cogging torques are significantly affected by such misalignments due to distorted air-gap flux density. However, the amplitude and the harmonics of the back-EMF are only slightly changed. Furthermore, the influence of the misalignments on the machine torque performance is investigated. It is shown that the machine torque is significantly reduced when the LSR axis is misaligned with the axis of the stator. Thus, it is concluded that the torque performance of axial flux magnetically geared machines significantly deteriorates under static and dynamic axis misalignments. In addition, the two types of misalignments have similar effects on machine performance. [ABSTRACT FROM AUTHOR]

The problem of high ripple in output torque is inherent to switched reluctance and permanent magnet machines compared to conventional machines. Torque ripple is undesirable as it leads to increased audible noise, speed ripple, and fatigue. Torque ripple is more prominent in complex machines like TFMs. This paper aims to tackle the problem of torque ripple in the homopolar poly-phase transverse flux permanent magnet machine by machine design approach. Rotor pole shaping, increase in number of repetitions, and increase in number of phases have been considered to reduce torque ripple. The 3-D finite element simulations have been carried out for the considered variations in geometry. Results of nature of air-gap flux density at no-load, cogging torque, average torque, and % ripple in the output torque are used to comment on the effectiveness of the torque ripple reduction techniques. The objective of this research is to reduce the torque ripple in the output torque to 10%. The technique/combination of techniques resulting in reduced torque ripple has been suggested to be implemented in the prototype. [ABSTRACT FROM AUTHOR]

This paper considers the use of transverse flux machines (TFMs) as an alternative to radial flux machines (RFMs) in an in-wheel application for an electric vehicle. The base motor is an existing outer rotor surface-mounted permanent magnet machine with fractional slot concentrated windings and liquid cooling. Two topologies of TFM are compared against this base machine. The first topology is a mutual flux path (TFM-MP), while the second is a claw pole machine (TFM-CP). First, the proposed TFM topologies are studied using FEA to understand the torque capability of both topologies. Second, a comparison between two different pole numbers of each topology is compared with the performance of the benchmarking machine (BMM). The machines will be compared in terms of torque density, losses, efficiency, and power factor (PF). Finally, it is presented as a comparison on the torque capabilities when constraining the magnet mass. It is shown that the TFMs selected can deliver higher torques than the base motor during continuous operation, but have failed to deliver the required overload torque. Furthermore, low PF and low efficiency make these machines unsuitable for the application of this in-wheel traction motor. [ABSTRACT FROM AUTHOR]

Free-piston engines have the potential to offer a compact machine capable of delivering electrical power. In this work, the design and modelling of a linear tubular generator are presented and used to investigate the effect of the electrical machine design on engine performance. A cogging-force-reduction technique is presented and used as a case study to demonstrate the importance of the integrated design. [ABSTRACT FROM AUTHOR]

A constant voltage AC-DC converter based on digital assistant technology is proposed in this paper, which has rapid dynamic response capability. The converter operates in the PFM (Pulse Frequency Modulation) mode. According to the load state, the compensation current produced by the digital compensation module was injected into the CS pin to adjust the switching pulse width dynamically and improve the dynamic response. The control chip is implemented based on NEC 1µm 5V/40V HVCMOS process. A 5V/1.2A prototype has been built to verify the proposed control method. When the load jumps from idle to heavy, the undershoot time is only 7.4ms. [ABSTRACT FROM AUTHOR]

As a part of manufacturing of electrical machines, electrical sheets are cut to the desired shape by various cutting techniques, such as punching and laser cutting. This cutting process degrades the magnetic material near the cut edge, which should be included in the finite-element modeling of electrical machines. However, due to the nature of the cutting effects, the existing finite-element modeling of the cutting effect results in computationally heavy simulations. This paper investigates the application of mixed-order elements to model the cutting effect. The second-order nodal triangular elements are used near the cut edge, whereas transition/first-order elements are applied in the remaining solution domain. Furthermore, the accuracy of the presented method is analyzed with the traditional method. According to the simulations, the mixed-order elements returned accurate results significantly faster than the traditional finite-element-based approaches. Furthermore, the effect of the cutting on the machine performance is also studied by comparing its results briefly. [ABSTRACT FROM PUBLISHER]

The latest electric machine design procedure is a complex non-linear multi-constrained optimization problem that takes a considerable amount of time to calculate and analyze electromagnetic fields. To address this issue adequately, this paper proposes a new metaheuristic multi-modal optimization design procedure based on the modified water cycle algorithm and supported by a surrogate model using the compressed sensing method. The proposed approach explores multiple optimal solutions simultaneously with good computational efficiency by reducing the number of cost function calls used in the optimization process. The efficiency of the proposed method is investigated by applying it to a set of test functions. Furthermore, the validity of the proposed approach with respect to the application to an electromagnetic problem is verified by designing a brushless permanent magnet tachogenerator using it. [ABSTRACT FROM AUTHOR]

This Special Section on "Optimization of Electrical Machine Designs" summarizes the state-of-the-art on the latest researches carried out on the topic, both in the academic and industrial environments. Basically, all the electrical machine topologies and optimization techniques have been discussed in this Section, suggesting to the readers interesting solutions of several optimization problems related with modern applications. The second part of the special section (the first one has been published in the December 2017 issue of the IEEE Transactions on Industrial Electronics) includes 20 papers from a total of 44 accepted contributions. The studies included in the Part II are categorized in a table and are outlined to some extent in order to help the readers to quickly compare the main peculiarities of the mathematical approaches and the practical implementations. The Part II paper categorization of this Special Section presents a second set of four papers focused on the permanent magnet synchronous machines [ABSTRACT FROM PUBLISHER]

In this paper, a numerical tool is presented in the field of the computation of electrical unknown of an electrical machine, very suitable to solve non-symmetrical condition too by means of a very friendly computer evaluation. This software tool, written in MATLAB language, bases itself on a formulation of air-gap field distribution by means of the linear combinations of the most elementary components of m.m.f (in case of windings) or of flux density (in case of permanent magnets) called Window functions. Differently from the standard methods, that allow appreciable results only after laborious calculations and complicate mathematical approaches that consent to formulate the problem in convenient domain, the proposed technique approaches and solves any problem directly in the time domain. The other most important feature of this procedure is its easy implementation into a proper tool that allows a friendly utilisation both by non expert people and by specialists in design phase activity or during the computation of performances in transient operations or in test conditions. In the paper, this tool is proposed in order to solve three cases of electrical machines simulations: the results demonstrate the interesting performance of the proposed tool. [ABSTRACT FROM AUTHOR]

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The induction motor designed for the variable speed applications are different from those which are designed for constant speed applications. This paper deals with the method for the design of induction motor for variable speed applications starting from the analytical calculation of equivalent circuit parameters. Finally, the main dimensions of the motor geometries are provided by using the relation between the circuit parameters and geometries of a real induction machine. The proposed approach also minimizes the problems caused by the conventional motor design methods for the variable speed application. The effectiveness and accuracy of the proposed design can be verified through Finite Element analysis for practical design. [ABSTRACT FROM AUTHOR]

Design of an electric machine such as the axial flux permanent magnet synchronous motor (AFPMSM) requires a 3-D finite-element method (FEM) analysis. The AFPMSM with a 3-D FEM model involves too much time and effort to analyze. To deal with this problem, we apply a surrogate assisted multi-objective optimization (SAMOO) algorithm that can realize an accurate and well-distributed Pareto front set with a few number of function calls, and considers various design variables in the motor design process. The superior performance of the SAMOO is verified by comparing it with conventional multi-objective optimization algorithms in a test function. Finally, the optimal design result of the AFPMSM for the electric bicycle is obtained by using the SAMOO algorithm. [ABSTRACT FROM AUTHOR]

A finite-element analysis-based optimal design of an electric machine takes considerable time for its objective evaluation and has many local minima. Thus, selecting an appropriate global convergence optimization with fast convergence speed is necessary in the optimal design of an electric machine. In this paper, a novel global search optimization algorithm, mass ionized particle optimization (MIPO), is newly proposed. The MIPO is the population-based algorithm, which reflects the interactive force between the ionized particles. The global convergence and the convergence speed are validated by comparison with the particle swarm optimization, which have already been proved for its global convergence when applied to a well-known Goldstein–Price function as a benchmark function. In addition, the algorithm has been applied to the optimal design of an interior permanent magnet synchronous machine aiming for its torque ripple reduction. [ABSTRACT FROM AUTHOR]

The design of an electromagnetic machine is a nonlinear, multivariable, and multimodal optimization problem that incurs a great deal of computation time when calculating electromagnetic fields. To overcome these problems effectively, this paper proposes a new evolutionary multimodal optimization algorithm based on the Big Bang–Big Crunch method and aided by a surrogate model using the theory of compressed sensing. Its efficiency is demonstrated by assessing the optimization results for test functions. Moreover, to evaluate the feasibility of its application to an electromagnetic problem, an interior permanent magnet motor is designed using the proposed algorithm. The obtained results confirm that the proposed method has the ability to search for multiple optimal solutions with a good computational efficiency by reducing the number of fitness function evaluations during the optimization process. [ABSTRACT FROM AUTHOR]

Fe–Si alloy has a wide use in the iron core in transformers and electrical machinery, but the low electrical resistivity restricts its application at a relatively high frequency. A soft magnetic composite (SMC) is one of the ways to improve the electrical resistivity of the soft magnetic material. In this paper, an SMC is prepared using Fe–6.5 wt% Si powder coated with 10 wt% Ni0.5Zn0.5Fe2O4 nano-powder by spark plasma sintering at 793 K. The scanning electron microscope micrograph shows that the composite has a particular micro-cellular structure. The composite exhibits high electrical resistivity, low total loss, and good mechanical properties. [ABSTRACT FROM AUTHOR]

This article shows an application of a double source generator for windmills. It is shown the design and the principle of operation of the electric machine. This machine was modeled with using Solisworks program for creating design and Maxwell program for analyzing of magnet field. The result of modeling is shown too. [ABSTRACT FROM AUTHOR]

The drive train of a small scale magnetically levitated train reveals the principles of a mechatronic system and offers challenges related to design, construction and control. Therefore, it is used at the Institute of electrical Machines (IEM) of the RWTH Aachen University as a demonstrator for engineering solutions. Instead of being a part of a static predefined student laboratory, the small scale magnetically levitated train is part of dynamic individual student projects. This approach provides the advantage that the students are directly involved in the engineering process and gain motivation out of their personal ideas becoming reality. [ABSTRACT FROM AUTHOR]

This paper presents a study of the effects that the shoe shape of the teeth of electrical machines has on the performance and losses. This is done by considering a concentrated wound, high-speed permanent magnet generator. The paper investigates the influence of the tooth shoe shape on the machine magnetic circuit and the losses distribution based on analytical and finite-element analysis (FEA). A shape coefficient K {t} is proposed to provide an optimized design reference. A comprehensive analytical tool able to study the variations of the machine performance parameters is proposed. The deduced optimization function is normalized using the non-equilibrium relative weighting method, and then, it is processed via a genetic algorithm to achieve the optimized design. FEA is used to validate the proposed analytical tool and the optimum design. [ABSTRACT FROM AUTHOR]

This paper presents the results from a coupled thermal and power loss analysis of an open-slot permanent-magnet (PM) generator. The research focus has been placed on the winding design providing minimum power loss at an ac operation, together with low-cost manufacture. The analyzed PM generator is intended to operate at a fixed speed, allowing for the winding design to be finely tuned for a single operating point. Such a design approach has not been widely reported in literature, and the existing body of work is largely focused on variable-speed applications, where the winding design is a compromise between the low-speed and high-speed operating points for a given torque–speed envelope. The ac winding power loss has been analyzed for several winding variants with different conductor dimensions, accounting for the winding operating temperature. The calculated results suggest that, in the analyzed PM generator, a lower winding slot fill factor is preferable as compared with the more common approach, where the highest manufacturable winding slot fill factor is usually considered. The power loss predictions have been supplemented with the thermal analysis of the complete generator assembly for the winding variants considered, illustrating the importance and influence of the appropriate winding design on the power output capability of the fixed-speed PM generator. The most promising winding design for the minimum power loss at a rated operating point has been downselected for prototyping. The theoretical findings from the analysis have been compared with the experimental data from hardware tests on a stator winding section, showing close agreement. [ABSTRACT FROM PUBLISHER]

In this paper, a new software tool developed by the authors for ac winding design, optimization, and complete analysis is presented. In particular, this software can be used as a valid aid in design and analysis for a wide variety of motor and generator windings with generic number of phases (including the case of those machines in which some slots are left empty), pole pairs, slot number, and so on. The calculation of winding factors and the evaluation of their harmonic distribution is also accomplished. The software is implemented in the MATLAB programming environment. By means of some examples, covering the most relevant winding types, the capabilities of this software will be shown. In particular, integer and fractional slot, single- and double-layer winding, concentrated windings, imbrication, belt widening, and belt shifting techniques can be treated to reduce particular harmonics in the electromotive force (EMF) or in the magnetomotive force (MMF). Finally, the connections, the winding factor harmonic distribution, the total harmonic distortion (THD) of EMF and spatial distribution of both the MMF, the Görges polygon, and the flux density are shown together with an estimate of the differential leakage and the air-gap flux density spatial distribution. The software presented in this paper is very modular, highly structured, and flexible due to the conspicuous number of operations that it can fulfill. Clearly, for the sake of brevity and clarity, the authors limit to represent the main features of the software, without going into specific details of programming and coding. All the main mathematical relationships that are useful to solve the problem of design and optimization of the windings of rotating machines are hereafter presented. [ABSTRACT FROM AUTHOR]

This paper proposes a method to the model constraints from different models to run an optimization over models with different granularities. Through machine learning, the proposed method has proven to be able to accurately map the constraints and minimize the number of call to the model. It handles both continuous and discrete variables and mixes design rules to statistic approach to create a surrogate of the model. [ABSTRACT FROM PUBLISHER]

This original paper deals with a new approach for the study of behavior in nonlinear regime of a new three-phase high voltage power supply for magnetrons, used for the microwave generators in industrial applications. The design of this system is composed of a new three-phase leakage flux transformer supplying by phase a cell, composed of a capacitor and a diode, which multiplies the voltage and stabilizes the current. Each cell. in turn, supplies a single magnetron. An equivalent model of this transformer is developed taking into account the saturation phenomenon and the stabilization process of each magnetron. Each inductance of the model is characterized by a non linear relation between flux and current. This model was tested by EMTP software near the nominal state. The theoretical results were compared to experimental measurements with a good agreement. Relative to the current device, the new systemprovides gains of size, volume, cost of implementation and maintenance which make it more economical. [ABSTRACT FROM AUTHOR]

One of the main challenges in permanent magnet electrical machine design is cogging torque reduction. In this article, the magnet segmentation method is used for cogging torque reduction. For this end, each surface permanent magnet is divided into eight parts, and a symmetrical structure with equal angular widths and considering the angular gaps between them is used for minimizing a number of optimization parameters. In this article, three optimization algorithms—response surface methodology, genetic algorithm, and particle swarm optimization—are used to determine the optimal values of optimization parameters. Finally, the result is obtained that the optimum values of response surface methodology are more efficient than of those of the genetic algorithm and particle swarm optimization in cogging torque reduction, because the objective function of the response surface methodology is cogging torque that is calculated using the finite-element method, whereas the objective function in the genetic algorithm and particle swarm optimization is based on the analytical methods. However, the main objection of the magnet segmentation method is the simultaneous reduction of average torque with cogging torque. [ABSTRACT FROM AUTHOR]

This paper details the design considerations of a permanent-magnet three-phase synchronous machine for fault-tolerant operation. A multidisciplinary approach to the optimal design of the machine is adopted, targeted at minimizing the additional losses resulting from faulty operating conditions and accounting for the remedial control strategy implemented. The design of a closed-slot six-slot four-pole machine is presented. The machine is prototyped and tested to validate the analytical–computational performances predicted in the design and analysis stage under healthy and faulty conditions. [ABSTRACT FROM AUTHOR]

Prediction of acoustic noise distribution generated by electric machines has become an integral part of design and control in noise sensitive applications. This paper presents a fast and precise acoustic noise imaging technique for switched reluctance machines (SRMs). This method is based on distribution of radial vibration in the stator frame of the SRM. Radial vibration of the stator frame, at a network of probing points, is computed using input phase current and phase voltage waveforms. Sequentially, the acceleration of the probing network will be expanded to predict full acceleration on the stator frame surface, using which acoustic noise emission caused by the stator can be calculated using the boundary element method. [ABSTRACT FROM AUTHOR]

Inrush currents are an important factor in the design of electrical machines. The uncertainties in measurements of magnetic materials parameters propagate via fitted material laws into the simulation results. In this paper, generalized polynomial chaos is used to compute the solution statistics and perform an analysis of variance; by this, it is revealed which measurement points are the most influential. As fitting strategies, we compare the result for the Brauer model and a smoothing spline approach. This is an essential step forward compared with considering only the uncertainty quantification for analytical material curve models. [ABSTRACT FROM AUTHOR]

Cogging torque is a source of vibration and noise in PM machines. Its reduction is always sought by electrical machine designers. While its study, in radial-flux PM machines, can often be done using 2-D finite element analysis (FEA), 3-D FEA is always required when it comes to its study in axial-flux PM machines (AFPM). AFPM machines have an inherent 3-D electromagnetic structure. There is a rich literature concerning the study of cogging torque in AFPM machines. Indeed, most of the authors use 3-D FEA for its study. However, 3-D FEA is time consuming and always requires expertise to be done correctly. The goal of this paper is to show that alternative techniques, to study cogging torque in AFPM machines, do exist. It is shown that the analytical approach, used in this paper, can be as efficient as the 3-D FEA while saving a huge amount of time and necessitating less initial expertise. [ABSTRACT FROM AUTHOR]

For a permanent magnet machine, temperature rise due to the losses in the rotor can affect the performance of the permanent magnet. This is a critical problem for the designers of electric machine. These losses, especially eddy current losses in the conductive part of the rotor, cause heat which cannot easily be mitigate due to the mechanical structure. Therefore, it is very important to consider the losses in the designing step to ensure that the machine operates stably. The most common technique of reducing the eddy current losses is to divide them into smaller parts. The analysis for this segmentation structure is only possible in 3D-FEM (Finite Element Method) and though this requires a considerable amount of time during design step. Therefore, it is necessary to calculate the eddy current losses rapidly and accurately. In this paper, an eddy current loss analysis method in the retainer of the permanent magnet machine which has a high power density is proposed. First, the concept of effective conductivity is introduced to solve the segmentation problems not to use 3D-FEM. Also, in order to improve the accuracy of the proposed method, the skin effect which occurs in high speed driving region is considered and a FFT analysis is also performed on the harmonic components of air gap flux density. Finally the thermal analysis result which is based on the loss analysis result is also demonstrated and it is verified to compare with the thermal experimental results. [ABSTRACT FROM AUTHOR]

Layout optimization with ON/OFF information of magnetic material in finite elements is one of the most attractive tools in the initial conceptual and practical design of electrical machinery for engineers. Heuristic algorithms based on random search allow engineers to define generalpurpose objects. However, there are many iterations of finite element analysis, and it is difficult to achieve a practical solution without island and void distribution by using a direct search method, such as simulated annealing (SA), genetic algorithm (GA), and so on. This paper presents a layout optimization method based on GA. The proposed method can arrive at a practical solution by means of multistep utilization of the GA, and the convergence speed is considerably improved by using it in combination with reduction of the design space. [ABSTRACT FROM AUTHOR]

Since the start of transformers immersed in refrigerating liquid, the fluid traditionally used has been mineral oil. However, in recent decades, efforts have been joined in the search for alternatives with a lower environmental impact and which also satisfy the technical requirements of insulation and refrigeration in the transformers. Currently, insulating vegetable oils are available in the market, which may have lower environmental impact during their use and final disposition; nevertheless, their high cost and short time of use have limited their massive application. This work presents the thermal behavior evaluation of two distribution transformers at different powers immersed in dielectric vegetable oil, comparing their performance with that of two constructively equal transformers immersed in mineral oil. The results obtained reveal that the transformers comply with the requirements of existing standards. [ABSTRACT FROM AUTHOR]

A novel low-speed axial-flux-modulated motor is proposed for in-wheel applications in hybrid electric vehicles. The proposed motor breaks the traditional design rule which stipulates that the pole-pair numbers of the stator and the rotor must be equal. Special ferrite segments in the air gap are used to modulate the magnetic field. It has the merit of having a very high torque density at low speed. It can be fitted into very limited space, such as inside the wheel rim of electric vehicles. Compared with radial-flux-modulated motors (RFMM), its manufacturing and assembling process are simple and easy. Its performance is compared with that of an RFMM using two-dimensional and three-dimensional finite-element methods and the comparison results verify the validity of this proposed machine design. [ABSTRACT FROM AUTHOR]

Abstract: One of the important challenges in design of the PM electrical machines is to reduce the cogging torque. In this paper, in order to reduce the cogging torque, a new method for designing of the motor magnets is introduced to optimize of a six pole BLDC motor by using design of experiment (DOE) method. In this method the machine magnets consist of several identical segments which are shifted to a definite angle from each other. Design of experiment (DOE) methodology is used for a screening of the design space and for the generation of approximation models using response surface techniques. In this paper, optimization is often solved via surrogate models, that is, through the construction of response surface models (RSM) like polynomial regression. The experiments were performed based on the response surface methodology (RSM), as a statistical design of experiment approach, in order to investigate the effect of parameters on the response variations. In this investigation, the optimal shifting angles (factors) were identified to minimize the cogging torque. A significant reduction of cogging torque can be achieved with this approach after only a few evaluations of the coupled FE model. [Copyright &y& Elsevier]

The Halbach magnetized permanent-magnet (PM) motors can be designed to achieve high torque density and to realize hollow rotor structure with very low rotational inertia. In this paper, the design and analysis of Halbach-array-based PM motors, which can produce high output torque and meet the requirements for very fast dynamic performance, are presented. A design method is proposed to select the optimum dimensions of the Halbach-array-based PM machines. The analysis and design approach for the selection of the suitable stator winding distribution, while considering the effect of the end windings, are also presented. Loss analysis of the machine is carried out, and a simplified 3-D model is proposed for its thermal analysis. Detailed finite-element analysis results are provided for the verification of the performances of the designed machine. [ABSTRACT FROM AUTHOR]

A closed-form approximate formulation is proposed to establish a relationship between the uncontrolled generator (UCG) operation of interior permanent-magnet (IPM) motors at high speed and the constant power speed range (CPSR) and drive current capabilities. High-saliency IPM motors of the PM-assisted synchronous reluctance type are mainly considered in the analysis, since they are proved to have the most favorable ratio between flux weakening capability and UCG voltage. The results of the analysis show the tight relationship between the uncontrolled overvoltage and the CPSR of the drive. Moreover, where the uncontrolled voltage is higher, the relationship between the CPSR and the motor current amplitude becomes stiffer: For small current variations, a large reduction of the speed range can occur. The analysis is validated experimentally on two motors of very different size (500 W and 1 MW). [ABSTRACT FROM AUTHOR]

The focus toward advanced mobile tactical configurations for railgun power supplies has resulted in the evolution of five compulsator generations in the past 30 years from iron-core to air-core prototypes. However, the exact air-core field simulation and the complicated fabrication technique of an air-core compulsator are not clear enough for researchers. This paper presents a detailed description of a small-scale all-air-core compulsator, which has a novel topology. The unique feature of the all-air-core compulsator is that there are two armature windings in the stator, the primary armature winding for providing the main output pulse and the secondary armature winding for providing the voltage for self-excitation. This approach allows the optimization of each armature winding to its specific duty cycle for increasing the overall efficiency of the compulsator. The two armature windings are located in the stator and not in the rotor. The advantage of this configuration is that it is unnecessary to equip the large-energy-level brush- and slip-ring mechanism. It is necessary to improve the power density, stability, and life span of a system. The no-load and discharge simulation results of the all-air-core compulsator were presented. Then, the electrical and mechanical parameters were given. The process technology of the slotless windings and the subassembly of the stator and rotor were presented. The results of the pulse-excitation experiment validate the results of the simulation. [ABSTRACT FROM AUTHOR]

This paper presents the formulation of developed second order sensitivity analysis when applied to shape optimization in design of electrical machine problems. It used the second order sensitivity analysis based on numerical approach that is variable have mixed solution limits to the shape optimization problems which using with standard electromagnetic design analysis (EDA) software. Based on this numerical methodology; designers will be able to deal with practical design optimization of electrical machines using with standard EDA software. The applicability of the proposed methodology is demonstrated by optimizing the salient pole synchronous hydro generator. The results show that the sensitivity analysis technique is provided improvement of solution about %15 and would appear to have certain important advantages over the other methods. [ABSTRACT FROM AUTHOR]

Application of the second generation High Temperature Superconducting (HTS) YBCO tapes has been increasingly popular since the low-cost superconducting materials were discovered. This paper mainly presents the properties of two types of 2G YBCO tapes from American Superconductor Corporation (AMSC) and SuperPower, Inc, respectively. All superconducting materials are cooled by liquid nitrogen (77 K). At first, we will introduce the basic design strategy for synchronous motor and characteristics of superconducting materials. Then, the basic principle and algorithm for calculation and measurement of Ic and AC transport loss will be explained. Secondly, the novel measurement system using a high-precision digital lock-in amplifier is presented. Finally, we present and analyze simulation and experimental results for two types of YBCO tapes in bending condition. [ABSTRACT FROM AUTHOR]

Design of electric machinery using population-based optimization requires a highly computationally efficient means of predicting the field distribution as well as the lumped-circuit model parameters. This paper proposes and validates a relatively straight-forward analysis appropriate to this end. [ABSTRACT FROM AUTHOR]