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In this paper, we propose a design process for a plasmonic grating structure to induce the resonance at a target wavelength. In a specific condition, surface gratings may induce the surface plasmon propagation due to the diffraction and the resonance wavelength of the surface plasmon propagation is dependent on the grating shape. The grating configuration was designed by the topology optimization scheme based on the reaction-diffusion equation. To shift the resonance wavelength to the target wavelength, this paper maps the frequency response function to a probability distribution function (PDF). The mean value from the PDF becomes a part of the objective function and the design objective is set to minimize the distance between the present resonance wavelength and the target wavelength while keeping the energy intensity. The process of simulation and optimization was performed using the commercial package COMSOL combined with MATLAB programming. [ABSTRACT FROM AUTHOR]

Recently, electric power consumption has increased rapidly owing to the development of electric devices, and thus environmental problems such as global warming have come to the fore. Therefore, developed and developing countries are preparing various measures to prevent global warming. Minimum energy performance standards (MEPS) are one of the representative measures. MEPS is an efficiency regulation for induction motors that limits the minimum efficiency with regard to the power of the induction motors, in order to save energy. Studies have been conducted on induction motors to improve the efficiency and to satisfy MEPS. However, It is very difficult to satisfy the efficiency of induction motor for MEPS. Therefore, synchronous reluctance motors (SynRMs) are actively being studied to replace induction motors. In this paper, a SynRM is designed using a Kw-map. Moreover, to improve the output characteristics, the rib thickness of the SynRM is optimized using the response surface method. Finally, the validity of the design method, proposed in this paper is verified with a real test using the prototype. [ABSTRACT FROM AUTHOR]

This paper proposes the multi-material topology optimization for the simultaneous design of segmented permanent magnet (PM) arrays, coil, and iron materials in magnetic actuators. Specifically, the proposed approach can find the optimal layout and shape of PM, coil, and iron materials, as well as the optimal border and magnetization direction of segmented PM arrays. For designing the layout and shape of actuator components, the discrete material optimization-type material interpolation scheme is employed in this paper. To attain the design of segmented PM arrays, an orientation design variable in Cartesian coordinate is utilized with the penalization scheme for the discrete PM magnetization directions. To validate the effectiveness of the proposed actuator design approach, two numerical examples are presented. In the examples, the actuator components (i.e., segmented PM arrays, coil winding, and back iron) are designed aiming for maximizing the magnetic force magnitude acting on the actuator plunger. [ABSTRACT FROM AUTHOR]

For the purpose of saving energy resources, it is extremely expected to develop highly efficient electric motors. Different types of permanent magnet (PM) arrangement can significantly affect the performance of the motors. Conventionally, the arrangement of the PMs is determined by designer’s experience. This paper focuses on the optimal design of PM arrangement in PM synchronous motors (PMSMs). We present a general pattern of the PM arrangement in PMSM. By varying the parameters of the general pattern, it can produce different types of PM arrangement in the rotor. The employed approach combines the global optimization method with the finite-element method for solving the optimization of the PM structures. Based on the proposed general pattern and optimization methods, the best PM arrangement in the motor can be automatically determined. In order to reduce computing loading, this paper employs the response surface models for reducing the computing time of objective functions. In the end, numerical tests are designed to showcase the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a new asymmetric planar V-shaped magnet arrangement for a linear PM synchronous motor is proposed. Several magnet arrangements for the track of the proposed linear permanent magnet (PM) synchronous motor such as un-skewed magnets, conventional magnet skew, and V-shaped planar magnets have been investigated. The performance results of the linear motor with skewed magnets are compared to those of previously designed PM linear synchronous motor with conventional un-skewed rectangular-shaped (CuSRS) magnets. The forcer is kept the same for all track structures and a thorough comparison is provided for low detent force and low force ripple with the CuSRS and proposed planar V-shaped magnet skew approaches. [ABSTRACT FROM AUTHOR]

In this paper, two novel double-sided hybrid-excitation flux-reversal linear motors (DSHEFRLM) with the surface (S-) and interior (I-) permanent-magnet(PM) arrangements are proposed and comparatively investigated. The proposed motors feature an asymmetrical double-sided primary configuration which enables the armature and field excitations to be placed separately. Through 2-D finite-element method (FEM), two motor structures with different slot/pole combinations are optimized, and then, the magnetic fields and electromagnetic performances are calculated, including inductances, no-load flux linkage, thrust characteristics, and PM demagnetization capability. By comparison, it is found that S-DSHEFRLMs show larger thrust density while I-DSHEFRLMs exhibit superior flux-adjusting capability. Finally, these predicted results are validated by 3-D FEM. [ABSTRACT FROM AUTHOR]

In this paper, we propose a hybrid genetic algorithm (GA) for the optimal shape design of an axially symmetric dual-reflector antenna by combining the GA with the moving least square (MLS), which enhances the convergence rate and the global search performance. The MLS is used to construct local interpolation functions from non-uniform sample data and to estimate new superior positions. By combining these superior positions in the next generation, the MLS-GA shows better search performance for the global optimum and a faster convergence rate than those of the conventional GA. To verify the proposed MLS-GA, we applied it to the optimal shape design of the DRA at the W-band. [ABSTRACT FROM AUTHOR]

This paper applied the finite-element method (FEM) with topological data structures to the optimization of electrical devices. A generic modifiable graph data structure is built according to the graph-theoretic foundation for these data structures. The employed topological FEM avoids rebuilding of the mesh in traditional FEM method while geometrical variations happen. It is an effective algorithm which can save computer storage and working time when applied to successive optimization. The effectiveness is verified by numerical example and comparison of the topological FEM with traditional FEM on storage load and working time is shown in this paper. [ABSTRACT FROM AUTHOR]

Linear antenna arrays consisting of dipole antennas find wide applications in wireless communication systems. Typically, arrangements with uniform spacing between the array elements are applied to gain highly directive radiation patterns while controlling the radiation intensity in the side lobes. To describe such arrangements, the so-called pattern multiplication (PM) technique is frequently applied, which inherently neglects the inter-element coupling. In this paper, an antenna array arrangement with non-uniformly spacing between the array elements is synthesized in the multi-objective sense. Therefore, the PM technique is deficient. Hence, numerical techniques have to be applied to compute the electromagnetic field during the optimization process. Due to its simplicity and the consequently reduced computational costs, the partial element equivalent circuit method is applied within the field computation process. The optimization relies on a stochastic particle swarm optimization strategy, namely the firefly algorithm. In this paper, an extended version of the general algorithm with additional hierarchical clustering is applied. Special attention is drawn to the development of a suitable objective function. [ABSTRACT FROM AUTHOR]

In this paper, optimization of the control of an electrical machine allowing a minimization of its total losses is described. It is based on the use of an iron loss model [loss surface (LS) model] coupled to the electromagnetic finite-element simulations of the machine. The LS model is a scalar and dynamic hysteresis model developed many years ago at G2Elab and tested for iron loss prediction in several cases of electric machines. It is first characterized and improved in this paper for M330-35A SiFe sheets. Then, it is associated with a finite-element analysis to compute, in a post-processor mode, the local and global magnetic losses in the machine. For electric vehicle application, the whole torque–speed variation should be investigated. To do that, a quick response surface is constructed from a small number of simulations and the iron loss is determined. Then, a suitable optimization algorithm is developed. This approach is then illustrated by a case study and compared with classical optimization in which only the copper losses in conductors are considered. Gains of up to 50% reduction in the total losses of the machine in certain operating areas are observed. [ABSTRACT FROM AUTHOR]

Social-spider optimization (SSO) is a new nature-inspired algorithm of the swarm intelligence field to global optimization applications, which is based on the simulation of cooperative behavior of social spiders. To enhance the performance of the standard SSO, a modified SSO (MSSO) approach based on beta distribution and natural gradient local search was proposed in this paper. In order to verify the performance of the MSSO, tests using Loney’s solenoid benchmark and a brushless direct current motor benchmark are realized comparing the effectiveness of the SSO and the proposed MSSO. The results of this paper demonstrated that the MSSO performance is promising in electromagnetics optimization. [ABSTRACT FROM AUTHOR]

This paper proposes an extended set of variables for numerical optimizations of tooth-coil permanent magnet synchronous machines (TC-PMSMs). The design variables for the extended set are chosen based on the magnetic asymmetries introduced by the saturated core under the loading conditions. The extended set allows to reach considerably higher values of torque density and significant reduction of torque ripple in comparison with a conventional set of optimization variables. The conventional and extended sets are compared on an example of an finite element method simulation of a double-layer winding surface permanent magnet-rotor TC-PMSM. A considerably better optimal machine is obtained when the extended set of variables is utilized. The paper showcases the design and the optimization of electrical machines using only free and open-source software. [ABSTRACT FROM PUBLISHER]

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]

The near-field communication (NFC) technique finds wide applications in many aspects of modern life, e.g., contactless payment systems or authentication. Regardless of the application, typically, the requirements on the antenna structure are manifold. Frequently, limitations in the available space make the antenna design quite challenging. Beside geometrical limitations, also the matching of the antenna structure to the analog front end of the NFC transponder IC has to be taken into account. Furthermore, the NFC antenna together with the connected IC has to fulfill specific standardized values. In this paper, the optimization of an NFC antenna structure including the needed matching circuit in the multi-objective sense is proposed. Due to its simplicity and the consequently reduced computational effort, the partial-element electric circuit (PEEC) method is applied to carry out the needed field computation in the so-called NFC operating volume. Furthermore, the PEEC method offers the possibility of simply connecting lumped components to the antenna structure within the numerical analyses, which enables the optimization of the matching circuit parallel to the optimization of the antenna structure. The optimization relies on a stochastic optimization strategy, namely, the firefly algorithm (FFA). In this paper, an extended version of the general FFA is applied. [ABSTRACT FROM AUTHOR]

The conventional topology optimization (TO) algorithm for an electric machine has a critical problem as the derivation of the impractical model to manufacture. In the case of a conventional step optimization, such as shape optimization (SO) after TO, the optimized model by TO is seriously distorted. To solve these problems, a hybrid optimization algorithm that conducts SO and TO simultaneously with the pre-processing and the post-processing is proposed in this paper. [ABSTRACT FROM AUTHOR]

Electromagnetic devices containing permanent magnet (PM) are common and typical electromagnetic devices that have advantages of low-power consumption, small size, high sensitivity, and its optimization problem has aroused widespread concern. Calculation accuracy of electromagnetic properties and efficiency of optimization processes are two important factors that affect the optimization effect of electromagnetic devices. A fast calculation method was proposed in this paper that aimed at electromagnetic devices with PM characteristics of strong non-linearity and low solving precision. The response surface method was used to derive the basis function, and the error between actual measured values and calculated values was modified by the Kriging method. On the basis of the calculation model, the distributed collaborative strategy was adopted to fulfill the parallel execution of the fast computation. Simultaneously, the updating strategy of particles was improved, and the robustness of the multi-objective particle swarm optimization algorithm in solving the optimization problem of electromagnetic devices with PM was enhanced. Effectiveness of the method proposed in this paper was verified by the case study of a specific type of electromagnetic relay with PM. [ABSTRACT FROM AUTHOR]

In this paper, we present systematic micromagnetic modeling investigation on recording process of segmented thin-film media with circularly polarized magnetic field at microwave frequencies. This paper provides insightful understanding about the segmented medium stack design in microwave-assisted magnetic recording (MAMR) by exploring the impact of signal-to-noise (SNR) ratio and recording track width. By utilizing segmentation of grains with exchange breaking layers, the ac magnetic field generated from spin torque oscillator can be best exploited. Via optimized medium stack design, MAMR is able to achieve both high SNR and areal density gain with the proposed notched-structure medium (top and bottom segments have the strongest crystalline anisotropy) compared with conventional graded medium (with gradually increasing anisotropy from top to bottom). By tuning crystalline anisotropy strength in top and bottom segment, we studied the MAMR behavior of SNR and track width under different ac frequencies. This provides a novel view for future segmented media design. [ABSTRACT FROM AUTHOR]

This paper deals with the optimal design of a new synchronous motor particularly suitable for electric vehicles. The unique advantage of this motor is its possibility to realize field weakening at high speeds, which is the most important demand for such drives. The main design goal is to identify the dimensions of certain crucial regions of the machine in order to avoid saturation of the iron and to minimize the mass to volume ratio, while simultaneously maximizing the torque. The originality of the contribution is manifold: formulating the design problem in multiobjective terms, solving it by means of evolutionary computing, solving the associated direct problem based on a three-dimensional finite element analysis (3-D-FEA) field model, considering a reduced set of design variables by means of response surface method, referring to a real-life problem. [ABSTRACT FROM AUTHOR]

Landmines still pose a serious threat mostly to civilians. Therefore, there is no doubt that working on the methods of landmines’ detection and liquidation should be considered extremely important. In this paper, we introduce the active infrared thermography with microwave excitation used in nonmetallic landmines’ detection. The effectiveness of the method is strongly dependent on the manner in which microwaves illuminate the ground. In this paper, we propose a new waveguide flange’s construction, which guarantees the uniform field distribution, and through this, a relatively uniform microwave heating on a certain area. The flange’s shape is based on box-horn. Its dimensions will be determined using a hybrid optimization algorithm. Results obtained in an optimization process will be validated using the numerical models. The experiments showing flange’s efficiency, concerning heating of sand itself and sand with buried landmines, will also be presented. [ABSTRACT FROM PUBLISHER]

Design of electromagnetic devices has multimodal, multidimensional, and constrained characteristics. Metaheuristic approaches are good choices for tackling these design problems owing to their simulation-based property. As many electromagnetic design problems require a long computing time to solve (even on modern computers) and many heuristic approaches have been created, the major goal of this paper is to improve the effectiveness and robustness of existing approaches. This paper proposes an algorithm with the ensemble of two composite differential evolution (DE) ingredients. One ingredient is biased toward exploration and the other is biased toward exploitation. The probability of choosing which ingredient to search for new solutions is adaptively updated based on the previous performance of each ingredient. The algorithm is applied to solve a loudspeaker design problem with promising performance when compared with DE, artificial bee colony, two improved artificial bee colony algorithms, and a randomly choosing ingredients algorithm. [ABSTRACT FROM AUTHOR]

This paper describes design techniques for a doublesided hybrid excited linear flux switching permanent magnet motor to achieve low force ripple while satisfying the required average thrust force. In this paper, we employ auxiliary poles fixed to both sides of the mover and determine the switching signal turn-on angle to reduce the force ripple in the initial design. Then, the sensitivity analysis of two split ratios is conducted to provide a feasible search direction for the optimization process. Finally, a finite-element-based optimization is utilized to minimize the force ripple and to satisfy the required average thrust force. Simulation results are validated by experimental measurement. [ABSTRACT FROM AUTHOR]

Recent expansion of emerging wireless power transfer technology has not been followed by an adequate systematic approach to the magnetic couplers design. The relation between design parameters (mutual inductance, coupling coefficient, leakage field flux density, coil quality factor, and so on) and structural parameters (coils and ferrite shape, size, thickness, and so on) has not been thoroughly explored, and practical designs often depend on trial-and-error methods supported by the finite-element modeling simulation to verify a final design. In order to fill that gap, this paper describes the adoption of multi-objective hybrid particle swarm optimization (MOHPSO) and multi-objective real-numbered particle swarm optimization (MORPSO) algorithms for a circular coupler design to increase performances and automate the design process. Objectives of this paper are threefold: 1) apply MOHPSO and investigate if there are some unconventional structures of circular couplers capable of outperforming traditional designs; 2) identify a minimum set of key optimization parameters for a circular magnetic coupler; and 3) demonstrate the operation of an MORPSO algorithm to optimize a circular magnetic coupler. The Pareto front concept is applied to provide multi-objective optimization. Two different multi-objective function pairs are considered, the first pair being the coil coupling coefficient ( k ) and maximum leakage field magnetic flux density ( B\max ); for the second pair, the product between quality factor ( Q ) and k is combined with ( B\max ). To validate the optimization algorithm effectiveness and accuracy, a selected magnetic coupler is fabricated and tested. Due to superior execution time, and satisfactory optimization capabilities, the MORPSO algorithm is employed to generate a final optimum design. Collected measurements demonstrate a very good agreement between the experimental and simulation results. [ABSTRACT FROM PUBLISHER]

A good magnetic design of a wireless electric vehicle (EV) charging system requires accurate characterization of the equivalent circuit parameters. This is while considering the effect of the magnetic core and the conductive shielding layers. In the literature, such an analysis is done using 3-D finite element analysis, which makes the design and optimization process time-consuming and computationally expensive. In this paper, an integrated analytical model for the characterization of a circular wireless power transfer EV pads is utilized. This analytical model provides a valuable tool to optimize the design process. This model is utilized when evaluating the objective function for each individual in the multiobjective Pareto Optimality optimization algorithm. The objective is optimizing the pads with three decision variables and four constraints. [ABSTRACT FROM AUTHOR]

Recently, the layout optimization of the secondary coils for wireless power transfer systems has been developed using the fixed grid (FG) representation. Although this method can effectively and efficiently determine the optimized coil design under the given conditions, a distinct discrepancy exists between the evaluated coil mass (i.e., simulation data) and the physical coil mass (i.e., experiment data). In this paper, the FG-based coil layout optimization is revisited based on the smooth boundary (SB) representation in order to resolve the inherent drawbacks of the FG representation. Induced voltage, electromagnetic field strength, and coil mass, which have been previously derived in the FG representation, are reformulated in terms of design variables (i.e., a reference turn and relative turns in this paper) in the SB representation. Through the layout optimization, the optimized layouts of the secondary coil are determined in order to minimize the coil mass while satisfying the constraints for induced voltage and magnetic field strength; then, they are postprocessed in order to obtain a smooth, elaborate boundary. The experimental validation demonstrates that the proposed SB-based approach outperforms the previous FG-based method in terms of coil mass and boundary representation. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study different permanent magnet (PM) bearings geometries based on PM rings with a minimum volume of PM for a given load. Simple and general scaling laws (SCLs) are proposed for each bearing geometry to predict its behavior. These SCLs allow a fast sizing of those geometries, as a function of the number of PM rings, the load reference, the air gap, and the remanent flux density. Those SCLs are derived for optimized topologies without any constraint on the geometrical parameters, as well as for optimized geometries with a constraint on the PM dimensions. For both cases, SCLs for the thrust-bearing stiffness are also proposed. [ABSTRACT FROM AUTHOR]

Proton precession magnetometer (PPM) is a potential device to measure the low-frequency geomagnetic field in the time domain. Nevertheless, the uncontrollable noise such as power frequency noise, random noise, etc., severely affects the detection results. In this paper, aimed to boost the performance of the PPM, a novel real-time processing algorithm for the optimization of PPM output strategy based on the low-rank constraint (LRC) is proposed, and a new efficient framework, dubbed LRC-based geomagnetic data readout optimizer (LRC-GDRO), is implemented. This method aims to extract the dominant principal components of the pure magnetic signal and identify the singular values of noise. Thereby, the relative ideal signal without external noise, which still contains the ambient field information is yielded. Moreover, we develop a prototype device and compare the test results before and after using the proposed method. Consequently, compared with traditional PPM, the performance of the PPM using the proposed method has been significantly improved with a measurement accuracy of ± 0.2 nT. Furthermore, the experimental results reveal that the LRC-optimized PPM is comparable to a very high-accuracy Overhauser magnetometer in terms of 12 h geomagnetic field observation. [ABSTRACT FROM AUTHOR]

This paper presents a multi-objective optimized design for a 75 kW, 24 000 r/min high-speed surface-mounted permanent magnet synchronous motor (SMPSM) for a magnetically levitated flywheel energy storage system. The main goal of the optimization process is to determine the optimal motor geometry, and thus obtain maximum efficiency, minimum weight, and minimum torque ripple in the SMPSM. To achieve this goal, three objective functions are used. The first function is used to obtain maximal output torque, and thus produce highest efficiency; the second function is used to minimize materials utilization to realize the lowest possible production cost; and the third function is used to achieve minimal torque ripple, and thus constrain the motor’s vibration and noise. The optimization process uses an ant colony algorithm with continuous domains. The optimized motor parameters can be selected from the Pareto solution set obtained. A comparison of the results calculated using the optimization algorithm with the results obtained using finite-element analysis software shows a good agreement. [ABSTRACT FROM AUTHOR]

This paper presents the design and optimization procedure of a novel mechanical-offset complementary-stator flux-reversal (MOCS-FRPM) machine. First, based on the original topologies, the pole-pair and flux modulation pole optimizations contribute to the high power density, efficiency, and larger torque capacity for the machine design. Second, based on the 2-D optimization results, the 3-D mechanical-offset structures are adopted for the torque ripple suppression. In fact, compared with the 3-D non-offset machine, the rotor mechanical-offset topology possesses the better torque performance, which can decrease the torque ripple by 34.6%, and with a slight 6.4% reduction of the torque average. Thus, through the proposed optimization procedure, the new complementary-stator machine accommodates the merits of the large torque capacity, low torque ripple, high efficiency, and high reliability. Also, the artful incorporation of the 2-D and 3-D optimizations leads to the reduced computation time and higher optimization efficiency. [ABSTRACT FROM AUTHOR]

Selective recording on multiple structures may be possible with microwave-assisted magnetic recording. The number of parameters in even a dual-structure system is such that optimization is difficult. In this paper, the response surface methodology is used to systematically optimize a dual-structure system. Optimized structures are presented for three different recording configurations, allowing random writes to either structure or writing in a predetermined order. The addition of a second structure could allow areal densities of over 3 Tbit/in2 to be achieved. [ABSTRACT FROM AUTHOR]

This paper proposes an adaptive particle swarm optimization (APSO) based on a kernel support vector machine (KSVM). The proposed algorithm improves the convergence speed and exploration capability of the APSO by employing an individual adaptive parameter control based on the KSVM. To verify the algorithm’s effectiveness, it was compared with both the conventional PSO and APSO based on test functions. Finally, we applied the proposed algorithm to the optimal design of a synchronous reluctance motor (Syn-RM). [ABSTRACT FROM AUTHOR]

In this paper, a novel control method is proposed for superconducting-hybrid magnetic levitation systems applied in conveyor manufacturing facilities. Recently, magnetic levitation systems are variously researched not only for high-speed transportation but also manufacturing process requiring the dust-free condition. The proposed controller consists of the inner feedback compensator and set-point error controller. The structure of the controller with convex set between conventional proportional–derivative–integral controllers guarantees the performances and robustness of the conventional controller and makes it possible to consider the additional properties that can be converted into linear matrix inequality constraints. The control factors are determined by solving the optimization problem with linear matrix inequalities to be expressed for time-domain specifications such as overshoot, rise time, and settling time and control input bound. The effectiveness of the proposed controller is verified by the simulation and finite-element analysis. [ABSTRACT FROM AUTHOR]

A novel electrodynamic suspension device using an asymmetrical double-sided Halbach array is proposed in this paper. A 3-D analytical model describing the eddy current field and the electromagnetic force is established via the second-order vector potential formulation. The validity of the analytical model is verified by both finite-element simulations and an experiment. The configuration of the proposed suspension device is optimized exploiting a dynamic kriging surrogate model assisted by a multi-objective genetic algorithm. The multi-objective optimization is performed utilizing the 3-D analytical model. [ABSTRACT FROM AUTHOR]

This paper presents the fast topology optimization methods for rotating machines based on deep learning. The cross-sectional image of electric motors and their performances obtained during a multi-objective topology optimization based on the finite-element method and genetic algorithm (GA) is used for training of the convolutional neural network (CNN). Two different approaches are proposed: 1) CNN trained by preliminary optimization with a small population for GA is used for the main optimization with a large population and 2) CNN is used for screening of torque performances in the optimization with respect to the motor efficiency. [ABSTRACT FROM AUTHOR]

This paper proposes a multi-objective optimization method using an adaptive weight determination scheme and tunneling method. To find the optimum designs that are evenly distributed on the Pareto front, the weights of different objective functions are adaptively determined by using the concept of a hyperplane so that new solutions can be gradually found in the objective space. In addition, to avoid locally optimized solutions that are dominated by other Pareto optimum designs, a tunneling method is employed in the optimization process. To confirm the effectiveness of the proposed method, topology optimization of the magnetic actuator is performed. The magnetic force and volume of the actuator are considered as two conflicting objective functions in the optimization problem, and Pareto optimum solutions that are evenly distributed in the objective space could be obtained. [ABSTRACT FROM AUTHOR]

This paper proposes dot sensitivity analysis of a current region for topology optimization. A continuum shape sensitivity formula is employed to derive a dot sensitivity formula in a simple closed form. The derived dot sensitivity formula provides the information on where the current dots should be created for topology optimization. This is necessary to generate the current dots in a vacant region of the design domain. Because this dot sensitivity analysis can obtain various topologies of material distribution, the possibility of local optimum convergence is reduced. Furthermore, because this dot sensitivity analysis does not require a specific initial design, its numerical implementation is simple. This dot sensitivity method is combined with the level set method to perform topology optimization. To demonstrate the usefulness of the proposed method, it is applied to two optimization problems of magnetic resonance imaging. [ABSTRACT FROM AUTHOR]

In this paper, a new permanent magnet (PM) linear motor is proposed. This motor has a special structure with complementary stator flux, which helps to reduce the flux leakage and improve the utilization of the PM. The PMs are installed in a leaning manner, which increases the effective area of the PMs and enhances the field excitation. Hence, the force density of the motor can be improved and it will be, especially suitable for applications within a limited space. The motor structure and working principle are first explained. The design of the motor is then comprehensively investigated. An electromagnetic optimization method based on tabu search algorithm and finite-element method is proposed for the motor to improve its force density. [ABSTRACT FROM AUTHOR]

Antenna array has been extensively applied to wireless communication systems. Optimal design of antenna array is very useful to attain desired spatial beam and reduce signal degradation. Potential search directions in artificial bee colony (ABC) algorithm are mixed with both large step size and small step size. This could lead to the malfunction of employed bee stage and onlooker bee stage of ABC algorithm. This paper proposes to improve the effectiveness of ABC by a similarity induced search method. This method adaptively adjusts search step size. Employed bees perform large step size search, while onlooker bees do small step size search. Scout bees could probe potential high-quality solutions in neighborhoods. The proposed algorithm is tested on antenna array design problem. Compared with four other algorithms, the results verify the effectiveness of the proposed algorithm. Furthermore, the scalability of the proposed algorithm is also analyzed in terms of array element and computational time. Scalability analysis also shows that the proposed algorithm is suitable for solving antenna array design problems. [ABSTRACT FROM AUTHOR]

Contactors are typical electromagnetic devices whose optimization is multi-objective optimization problems. Contactors’ static and dynamic characteristics obtained by the finite-element method (FEM) are typical objectives. Due to the low efficiency of FEM, the intelligent optimization algorithms that require multiple computations cannot be applied well here. In this paper, a fast algorithm for characteristics of contactors based on radial basis function neural network approximate model is proposed. The orthogonal least squares, data pre-processing and subsection modeling methods are adopted here to make the model more accurate. Meanwhile, a hybrid multi-objective optimization algorithm which combines the differential evolution and the particle swarm optimization is also proposed to speed up convergence and obtain the limit optimal solutions. The feasibility of the above-mentioned methods has been verified by solving a multi-objective optimization problem of the contactor with solenoid structure. [ABSTRACT FROM AUTHOR]

Multi-phase topology optimization (TO) is able to determine the optimal distribution of two or more different materials in combination under some volume or weight constraints and is a very common problem in the engineering design area. To perform multi-phase TO, a new methodology based on the multi-label graph cut theorem is proposed in this paper. More specifically, the multi-label expansion move included in the theorem is able to solve the multi-phase TO problem without requiring a large amount of memory and time. According to the numerical results as reported, the proposed methodology can find the optimal topology of a multi-phase materials distribution with a significant improvement in the performance parameter. [ABSTRACT FROM AUTHOR]

A new type of three-phase stator hybrid excited machine with permanent magnets (PMs) located at the slot openings of field winding slots is presented in this paper. It has the advantage of good flux regulation capability due to the field excitation. The machines with different stator/rotor pole combinations, i.e., 6-stator pole and 7-/8-/10-/11-/13-/14-rotor poles, have been comparatively investigated in terms of the open-circuit and on-load characteristics, as well as the influence of dc current and the unbalanced magnetic forces. The 2-D finite element analysis (FEA) has been employed for analysis and optimization of the machines together with experimental validation. [ABSTRACT FROM AUTHOR]

Switched reluctance (SR) machines are attractive because they present relatively high efficiency and torque density in spite of lacking permanent magnets. This paper focuses on a two-objective optimization of an external rotor SR motor with a stator that has concentrated coils and a rotor with magnetically isolated modules. The objectives are minimum loss and mass, and 11 independent dimensionless geometric variables are considered as inputs that affect them. A combined design of experiments (DOE) and differential evolution (DE) approach is proposed. The DOE methodology is used to reduce the search space by eliminating from consideration input variable values, leading to poor-performing designs. Following this initial DOE study, an optimization study based on DE is run over the reduced search space, which leads to significant savings in computation time. Furthermore, a directed graph-based method for comparing different designs on the Pareto front to rank the best compromise designs is proposed. [ABSTRACT FROM AUTHOR]

Optimal design of electric machines using finite-element analysis (FEA) necessitates too much computation time to maintain high accuracy. To reduce the computation time and obtain a global optimum in multi-modal problems, this paper presents differing extent mesh adaptive direct search (DEMADS). The proposed algorithm is classified into three groups according to the poll searching frame and mesh size for assigning a global and local searching. In particular, DEMADS shares information among solutions based on a parallel multi-start strategy for earlier stopping by deviation and checking revisits. The effectiveness of DEMADS has been validated and evaluated as the function call number and the convergence number at a global optimum using benchmarking function. Finally, it is applied to an optimization problem that minimize torque ripple of a spoke-type permanent magnet synchronous machine via FEA. [ABSTRACT FROM AUTHOR]

A new flux-assisted consequent pole spoke-type permanent magnet (PM) synchronous torque motor is proposed in this paper. The proposed motor has fractional slot structure with a spoke-type rotor geometry and flux-assisted magnets. Initial design, rotor design optimization, detailed 2-D and 3-D finite-element analyses (FEAs), and structural and thermal simulations are all carried out. A prototype motor is built and tested. The optimized design is validated by 2-D/3-D FEA and experiments and compared with the reference conventional surface PM (SPM)-type torque motor. The results indicate that the proposed new motor has higher torque-to-magnet-weight ratio and wider constant power region than the conventional SPM synchronous torque motor. [ABSTRACT FROM AUTHOR]

This paper presents an effective design method for inductors which is based on the multi-objective optimization accelerated by the artificial neural network (ANN). In the learning phase prior to the optimization phase, ANN is trained for 1000 input–output data sets obtained from the finite-element analysis for randomly generated dimensional parameters. The magnetic hysteresis of the ferrite core is modeled by the play model to evaluate the hysteresis losses. The multi-objective optimization problems are solved by the genetic algorithm in which the magnetic loss is effectively computed by the trained ANN to reduce the core volume as well as magnetic loss. The Pareto solutions for an EI-shaped ferrite core are obtained for different inductances. It is shown that the proposed method works much faster than the conventional optimization, and the magnetic loss and the inductance of the optimized inductor agree well with the experimental results. [ABSTRACT FROM AUTHOR]

High-speed permanent magnet synchronous machine (PMSM) can provide high power density and high efficiency, which is often highly desirable in high performance applications. A multi-physics optimization program based on the multi-objective genetic algorithm was developed in this paper, to achieve a tradeoff solution between the electromagnetic, mechanical, and thermal aspects. First, the parametric electromagnetic model was modeled based on the finite-element method, and then a thermal network model and an analytical mechanical model to determine the thickness of the magnet and the sleeve were developed and merged within a design cycle of the machine, in an effort to attain the target performances of 20 kW/kg at 20 000 r/min for a 2 MW PMSM. Optimization results indicated that a final design with eight poles and 48 slots could obtain a comprehensive performance between power density and efficiency, and the performance satisfied all the requirements. [ABSTRACT FROM AUTHOR]

This paper describes a new method aiming at the multi-objective optimization of a transverse flux machine with a claw-pole and flux-concentrating structure (CPTFM). Considering the 3-D main magnetic flux in the CPTFM, the time-consuming 3-D finite-element method (FEM) should be used to accurately analyze the performance of the machine. In order to reduce the calculation time for the optimization of the complex CPTFM, the Taguchi method is first applied to evaluate the importance of all the design parameters in the consideration of the predefined five objectives. Subsequently, a mathematical model is developed to replace the 3-D FEM, so that the objectives depending on the selected four critical parameters can be analytically calculated. With its help, the four parameters are further optimized with the multi-objective particle swarm optimization method and nondominated sorting genetic algorithm 2. Finally, the optimal design of the CPTFM is selected from all the searched Pareto solutions with the help of fuzzy logic. It can be concluded that the developed method is effective and efficient, which can make an appropriate compromise between the calculation time and the improvement of the machine performance. [ABSTRACT FROM PUBLISHER]

Following a study on the optimal write head design for perpendicular magnetic recording, this paper aims at optimizing the design of write head for shingled magnetic record by applying the Taguchi method and the response surface methodology. The criteria for the evaluation of the write head design are to maximize the signal-to-noise ratio (SNR) and minimize the bit error rate (BER) in the shingled magnetic recording (SMR). In this paper, the magnetic fields of the write head designs are modeled using finite-element analysis, the SMRs are simulated by applying micromagnetic modeling based on Landau–Lifshitz–Gilbert equation, and the SNR and the BER are characterized using the grain flipping probability model. An optimal design of the write head is obtained to achieve the maximum SNR and the minimum BER. A discussion on the erasure band width is also carried out in this paper. Furthermore, the SNR and the BER at different bits and track densities in SMR are compared and discussed. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to propose an efficient and unique reluctance network (RN) model for all translator displacements of a linear hybrid motor. This model has to consider several translator positions to analyze the linear motor performances. The proposed RN model takes into account the magnetic characteristic and the flux leakage. Consequently, the proposed model gives precise results of the electromagnetic characteristic. The RN model considers an interesting solution to deal quickly with an optimization task of a large number of constraints and parameters. The developed model is coupled with sequential quadrating programming method for an optimization process of the linear machine. The obtained results confirm the efficiency of this method for modeling and optimization of the linear machine. [ABSTRACT FROM AUTHOR]

This paper presents an approach for improving the process of optimal design of permanent-magnet (PM) motors. A finite-element method (FEM) combined with a dynamic dual-response-surface model (dual-RSM) is proposed to compute an objective function. The FEM is employed as a basic tool for the computation of the objective function. In order to build up the dual-RSM model, a radial basis function and a moving least-square approximation are both employed. The results that are obtained from the dual-RSM model are dynamically compared together with a preset goodness-of-fit, which determines whether the accuracies of the dual-RSM are high enough to replace the FEM computation. This strategy makes the FEM computation not always necessary at all the sample points in the optimization process and ensures the accuracy of the solution. For the purpose of showing the effectiveness of the proposed optimization methodology, the optimal design process of a dual PM-excited synchronous motor is taken as an example in this paper. [ABSTRACT FROM AUTHOR]

Two-reader two-dimensional magnetic recording (TDMR) system is expected to improve areal density by about 10%, although practical considerations may limit the realization of all of the available gain. As a result, for further growth, hard-disk drive industry has started to develop the second-generation TDMR system, consisting of three readers. Although a natural evolution of the first-generation, it brings its own issues and challenges. In this paper, we study the behavior and optimization of the three-reader system with a particular focus on reader placement and cross-track error-correction coding gains. In addition, we consider a lower cost two-reader solution with streaming intertrack interference cancellation as an alternative to employing three readers. [ABSTRACT FROM AUTHOR]