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This aim of this paper is to assess the efficacy of mesh-based generated reluctance network (MGRN) modeling for the performance evaluation of a permanent magnet linear machine under load conditions. In the previous publications related to the use of this modeling technique, only approach implementation under an open-circuit performance has been assessed. The MGRN approach is based on the discretization of the geometry using elementary reluctance blocks (reluctance elements). This modeling technique has been implemented in a software tool that allows the automated processing of an arbitrary geometry providing a gain in model development durations. Validation of the MGRN model has been realized by comparison with a finite element analysis (FEA). Comparisons showed that both local and global quantities evaluated by MGRN and FEA are in excellent agreement. [ABSTRACT FROM AUTHOR]

The aim of this study is to analyze the vibration behavior of a five-phase flux switching machine in order to detect and discriminate full and partial open-phase faults. To achieve our goal, radial magnetic stress was calculated by two magnetic models. The first magnetic model, presented in this paper, is obtained by finite element analysis (FE) and the second one by permeance network analysis (PN) of the studied electrical machine. Stator radial accelerations were evaluated coupling each of the two magnetic models with an analytical mechanical model. The results of two multiphysics models are compared with experimental results, in order to validate them. Experimental measurements are performed under healthy and faulty conditions, at fixed rotational speed. For faulty conditions, full open-phase and partial open-phase fault of the stator winding were analyzed. [ABSTRACT FROM AUTHOR]

This paper presents performance improvements of a double excitation synchronous motor by using a reluctance network (RN). The distinguishing feature of the double excitation principle is to use permanent magnets with high energy, while air-gap flux is flexibly controlled by field windings. Therefore, the first contribution of this paper focuses on maximizing air-gap flux range control. Second, an approach for torque ripple reduction is proposed by directly modifying air-gap flux according to the instantaneous torque profile. The achieved resultant torque stays almost constant for a case study. The validity of the RN method is examined by comparisons with 3-D finite element and experimental results for several machines. [ABSTRACT FROM AUTHOR]

This paper presents 3-D finite-element analysis of a new double excitation synchronous machine. It is shown that the machine has true field regulation capability. The principle of operation and design aspects of this new machine are presented in the paper. Comparison of 3-D FEA with an experimental study done on a prototype having a different rotor structure is also investigated. [ABSTRACT FROM PUBLISHER]

This paper describes an analytical model for computing the rotor eddy-current losses in the case of permanent magnet synchronous machines, based on a formal resolution of Maxwell’s equations. We focus on the computation of the eddy currents in the machine magnets, in which the diffusion equation is analytically solved, using an accurate electromagnetic model of the stator slotting. The model originality lies in its capacity of taking into account both the diffusion phenomenon and the magnet’s finite length over the pole pitch, imposing that the total current over the magnet’s surface should be zero at each instant. This important problem is studied by solving a Fredholm integral equation. A validation using a 2-D time-stepping finite-element model is also performed, and the obtained losses are shown to be in good agreement with those given by the analytical method, for a shorter computation time. [ABSTRACT FROM AUTHOR]

This paper presents two short-circuit fault models of a hybrid excitation flux switching permanent magnet machine, i.e., excitation phase short-circuit and interturn short-circuit in excitation windings. Two-dimensional finite element (FE) method is used to calculate the major parameters, such as armature and excitation inductances, which are not only functions of rotor position, but also of armature and excitation currents. Moreover, in case of short-circuits, the variations of armature and excitation currents are often significant. This in turn leads to an important change in winding inductances. Therefore, in order to precisely predict machine performance under short-circuit conditions, the use of inductances versus rotor position and RMS currents is essential. With the obtained FE results, two MATLAB/Simulink-based models are established. Then, the previously mentioned short-circuits have been studied and their influences on electromagnetic performances, such as armature and excitation currents, speed and torque, armature and excitation copper losses, stator and rotor core iron losses, as well as permanent magnet (PM) eddy current losses are analyzed. Experiments have been carried out to validate the simulations. [ABSTRACT FROM PUBLISHER]

In this paper, an analytical method for the computation of the electromagnetic field in the airgap of an inset permanent magnet synchronous machine is proposed. The originality lies in the fact that both the stator and rotor saliencies have been taken into account in the analytical procedure. The purpose in to compute both quickly and accurately the magnetic fluxes and instantaneous torque of the machine, in order to minimize torque ripples in an optimal predesign process. It is shown that the instantaneous torque is in good agreement with finite element results, for a shorter computation time. The model presented here can be used when the 2-D approximation of the machine is valid, which is the case for most of machines' topologies. [ABSTRACT FROM AUTHOR]

This study presents a fault-electromagnetic-thermal model of a fault-tolerant dual-star flux-switching permanent magnet motor. The analytical results in terms of phase currents, rotor velocity and output torque are firstly calculated by a Simulink-MATLAB-based fault (short-circuit) model. Then, the fault and normal phase currents are used in the motor 2D finite element method (FEM) model to calculate the copper and iron losses. As the main heat sources in electrical machines, the obtained copper and iron losses are used in the lumped parameter (LP) and the 3D FEM thermal models to calculate the temperatures of different machine components. Finally, the variation of temperatures of the machine in the presence of faults can be predicted. The results obtained by the LP and the 3D FEM models are also validated by experimental tests. A good agreement has been observed among the analytical, numerical and experimental results. In order to realise the 3D FEM model of the doubly salient rotating machine, a method to transform the salient rotor into a non-salient one have been proposed. Some methods are also proposed to enhance the performance of the cooling system and decrease the maximum temperature of the machine. [ABSTRACT FROM AUTHOR]

This paper presents copper and iron loss models of a classical switched reluctance motor (SRM) and a mutually coupled switched reluctance motor (MCSRM). The iron losses in different parts of machines are then detailed. Based on the power losses model, a lumped parameter (LP) transient thermal model during driving cycles is performed, the analytical results are validated by the finite-element (FE) transient thermal model. Special attention has been paid to model the salient rotor and a method to transform the salient rotor into a nonsalient one has been proposed. A comparison between the maximum temperatures obtained by using different heat source (average power losses or instantaneous power losses during driving cycles) is given. The experimental tests are also realized to verify the analytical and numerical results. [ABSTRACT FROM PUBLISHER]

We describe a 3-D analytical model based on formal resolution of Maxwell's equations of a permanent-magnet linear actuator, with circular-shaped magnets. We present all details of the 3-D analytical calculation for the no-load flux and then compare results obtained by this model to those obtained by 3-D finite-element analysis. The comparisons show a good agreement between the two models and so validate our analytical model. Unlike 3-D finite-element analyses, which are time consuming, the analytical models that we present in this paper are suitable for an optimization process of such a structure. [ABSTRACT FROM AUTHOR]

Switched reluctance motors (SRMs) are highly advantageous electric motors for various industrial applications, particularly in electric vehicles (EVs), due to their winding-free rotor, magnet-free design, simplicity, and ease of manufacturing. The growing interest in axial flux SRMs (AFSRMs) is particularly noticeable, as axial flux electric motors with a flat shape and high aspect ratio have become commonly used in various industrial applications, including in-wheel motors for EVs. Structurally, AFSRMs significantly differ from radial flux SRMs (RFSRMs), but share the same electromagnetic operating principles. When compared to RFSRMs, AFSRMs generate higher torque per unit volume due to their more effective utilization of their air gap. In this study, the axial force on the rotor and torque ripple of a 6/4 pole fully pitched axial flux SRM (FP-AFSRM) were minimized by combining the advantages of "single-stator and single-rotor AFSRM" and "double-stator and single-rotor AFSRM" models. The proposed FP-AFSRM model, which has a "double-stator and single-rotor AFSRM" design and has the operating logic of a "single-stator and single-rotor AFSRM", was analyzed using 3D finite element analysis. The results show that the torque ripple decreased (Δ % Trip) between (−30.42) and (−41.14), and the axial force on the rotor decreased between 17.61% and 25.4%. [ABSTRACT FROM AUTHOR]

The Hybrid Excitation Flux Switching Permanent Magnet (HEFSPM) motor with magnetic bridge is a topology of hybrid excitation Flux-Switching Permanent Magnet (FSPM) machines. Despite its excellent performance such as high torque/power density, high flux enhancing/weakening capability and so on, it has received less attention due to its complicated structure. Therefore, its optimal design and performance all need to be further investigated. This paper presents a multi objective optimization design of a HEFSPM motor with magnetic bridge based on design sensitivity analysis. At first, the machine structure and basic working principle are discussed briefly. Then, a design sensitivity analysis for geometric optimization is carried out to improve the motor performance. This optimized motor is compared with initial design. Finally, a prototype of the optimized proposed motor is built and tested to validate the simulation results. [ABSTRACT FROM AUTHOR]

This paper discusses the construction and operating principle of an axial flux electric machine with hybrid excitation. Based on computer simulations using the Finite Element Method, an analysis was conducted with changes in the geometry of the magnetic circuit, which involves the rotation of the rotor disks relative to each other on the operating parameters of the machine. Both the generator state of operation, in the meaning of analyzing the induced voltage (adjustment at −11% ÷ +64%) and the cogging torque, and the motor state of operation, in the meaning of analyzing the ripple of the electromagnetic torque (possible reduction by almost 30%), were examined. The article concludes with observations on how the change in the angle of the rotor disks affects the efficiency of the disk machine with axial flux and hybrid excitation. [ABSTRACT FROM AUTHOR]

This paper presents a two-dimensional analytical model for brushless double-rotor flux-switching permanent magnet machines (BDRPFSPMM) with yokeless stator recognized as a type of partitioned-structure flux-switching permanent magnet that is an appropriate machine to be employed as the electric motor in industry. The most salient advantages of the proposed machine are low iron loss due to volume of iron in stator and high space of stator slot for winding. The radial and tangential components of the magnetic flux density due to permanent magnets and armature currents in each active domain of the machine, electromagnetic torque, self- and mutual inductance, unbalanced magnetic force (UMF), and local traction are calculated based on the subdomain method. Teethes on both rotor and stator structures are effective on magnetic quantities, so interactions of rotor and stator saliency are considered. The method is general for the magnetic field calculation with any combination of rotor- and stator-pole number. To validate the proposed model, the analytical outputs are compared with those obtained from the finite element method (FEM). [ABSTRACT FROM AUTHOR]

Silicon rectifier generators, which are single-excitation generators, are commonly used in vehicles. However, a traditional single-excitation generator cannot satisfy the requirements of modern vehicles due to its low efficiency, high failure rate and large excitation loss; a hybrid excitation generator is more suitable for a wide range of applications in vehicles because of its many advantages. In this study, a novel, high-efficiency and energy-saving hybrid excitation generator with a claw-pole series magnetic circuit for vehicles was designed. The magnetic circuit and principle of operation were analyzed. The structure parameters of the hybrid excitation generator were initially designed according to motor design theory. The model of the hybrid excitation generator was built based on the finite element method, and the no-load characteristic was analyzed. Furthermore, the influences of the permanent magnet thickness and core slot width on the performance of the generator were analyzed. According to the results, the structural parameters were optimized. The no-load output characteristics and load characteristics were compared between the generator and a silicon rectifier generator, and the test results show that the design, simulation and optimization methods were reasonable. This provides theoretical support and research methods for the development of a hybrid excitation generator. [ABSTRACT FROM AUTHOR]

In this study, a generalized torque estimation method is proposed for synchronous motors, including surface permanent magnet synchronous motors (SPMSMs), synchronous reluctance motors (SynRMs), and interior permanent magnet synchronous motors (IPMSMs) for building the analytical motor model. The average motor torque is estimated using the Lorentz force by the generated flux density in the air gap to determine the relationships among torque, flux density, and injected current. In the proposed method, the generated flux density is derived step by step by considering the effects of magnetic flux saturation, the stator slot, the rotor barrier, and permanent magnets (PMs) to ensure that the generated average torque complies with the operating condition of the motor. To verify the proposed method, the output torque of finite element analysis (FEA), Maxwell 2D, is compared to the proposed method in a SPMSM. Moreover, a phasor diagram is plotted to determine the mechanism through which torque is generated in SynRMs and IPMSMs. A SynRM and an IPMSM with ferrites PMs are analyzed using the proposed method, FEA, and the experimental results of this study indicate the effectiveness. [ABSTRACT FROM AUTHOR]

This paper is the first that proposes an extended hybrid analytical method (HAM) based on a two-dimensional (2-D) coupling between the semi-analytical Maxwell-Fourier analysis and finite-element method (FEM) in polar coordinates. The proposed model is applied to any rotating electrical machines. The main objective of this paper is to establish the magnetic field solution in the whole machine by coupling an exact analytical model (AM), proposed for all regions having relative magnetic permeability equal to unity, with a FEM in ferromagnetic regions. The AM and FEM are coupled in both directions (r , θ) in the edge separating teeth regions and all its adjacent regions by applied boundary conditions (BCs). The developed HAM gives accurate results on the magnetic flux density distribution and the cogging torque whatever the operating conditions, the magnetic or geometric parameters. All results obtained give very satisfactory agreement with 2-D finite-element analysis (FEA). [ABSTRACT FROM AUTHOR]

In this paper, a variable reluctance generator with segmental stator utilizing an assisted DC field for variable speed applications is proposed. In this work, analytical design, magnetic field analysis, and Parametric Sensitivity Analysis of the proposed machine are presented. The stator of suggested configuration, in addition to the distributed phase windings, is included the distributed assisted dc field coils, which are responsible for producing an adjustable magnetic flux in the generator. The segmental stator, the controllability of magnetic flux and generated voltage are the prominent features of the presented generator. Maintenance-free and easy accessibility of each stator segment due to utilizing the segmental stator, and high reliability due to the absence of brush and winding on the rotor is other features of the proposed machine. Finally, the Field Analysis using the finite element method is performed to verify the analytical design and sensitivity analysis. The results obtained from the FE analysis confirm the analytical design and the controllability of magnetic flux and generated voltage for the proposed configuration. [ABSTRACT FROM AUTHOR]

This paper presents a topology for the brushless operation of a wound-rotor synchronous machine based on the subharmonic excitation technique by using two sets of multi-pole windings on the armature as well as on the rotor. The armature windings consist of a four-pole three-phase main winding and a two-pole single-phase additional winding, responsible for the generation of fundamental and subharmonic components of magnetomotive force (MMF), respectively. The rotor contains four-pole field winding and two-pole excitation winding. From the generated air gap MMF, the additional winding is responsible for induction in excitation winding, which feeds DC to the field winding through a rotating rectifier without the need of brushes. Then, the interaction of the magnetic field from the main and the field windings produces torque. The proposed topology is analyzed using 2D finite element analysis (FEM). From the analysis, the generation of the subharmonic component of MMF is verified, which helps in achieving the brushless operation of the wound-rotor synchronous machine. Furthermore, the performance of the proposed brushless multi-pole topology is compared with the existing dual three-phase winding multi-pole topology in terms of current due to induction, output torque, torque ripples, and efficiency. [ABSTRACT FROM AUTHOR]

Featured Application: Stand-alone wind power generator. In this paper, a novel mechanical flux-weakening design of a spoke-type permanent magnet generator for a stand-alone power supply is proposed. By controlling the position of the adjustable modulator ring mechanically, the total induced voltage, i.e., the amplitude of the back EMF vector sum can be effectively adjusted accordingly by the modulation effect. Consequently, the variable-speed constant-amplitude voltage control (VSCAVC) with a large speed range can be achieved. Compared to the electrical flux-weakening method, the mechanical flux-weakening method is easier to operate without the risk of PM demagnetization. The analytical model is presented, and the operation principles are illustrated. To analyze the performance of different combinations of stator/rotor pole pairs, four cases are optimized and analyzed using the finite element method for comparison. The characteristics of VSCAVC are analyzed. [ABSTRACT FROM AUTHOR]

In this paper, a design methodology for synchronous reluctance machines (SynRM) working with variable torque and speed profiles was presented. Unlike conventional solutions which size the machine considering a reduced number of working points in order to reduce the computation time, the solution proposed in this paper takes into account all the points which allow for better management of the constraints along the cycle to avoid an oversizing of the machine. To solve this problem with a reduced computation time, the geometry of the motor as well as the control strategy were optimized in two steps. In the first step, the d-q axis stator currents were analytically expressed. In the second step, the geometry was optimized with the use of a genetic algorithm. As an application of this method, the case of a small and low-cost electric vehicle (EV) was chosen with the objective of minimizing both the mass and the energy lost for the standardized urban dynamometer driving schedule (UDDS). The method was based on the use of a 1-D analytical model which was validated by a 2D finite element analysis (FEA). [ABSTRACT FROM AUTHOR]

The reluctance machine is a potential candidate for electrical vehicle propulsion because of its reliable structure, low cost, flexible flux regulation ability, and wide speed range. However, the torque density is unsatisfactory because of the poor excitation ability and low stator core utilization factor. To solve this problem, in this paper, a novel hybrid reluctance machine (HRM) with the skewed permanent magnet (PM) and the zero-sequence current is proposed for electric vehicles. The skewed PM has two magnetomotive force (MMF) components with different functions. The radial MMF component provides extra torque by the flux modulation effect. The tangential MMF component can generate a constant biased field in the stator core to relieve the saturation caused by the zero-sequence current and thus improve the utilization factor of the stator core. Therefore, torque improvement and the relief of stator core saturation can be simultaneously achieved by the skewed PM. In this paper, the machine structure and principle of the proposed machine are introduced. And ultimately, the machine's electromagnetic performances are evaluated under different PM magnetization directions and zero-sequence current angles by using finite element analysis (FEA). [ABSTRACT FROM AUTHOR]

Hybrid excited machine (HEM) is a novel type of machine which has attracted much attention as it is able to adjust the flux linkage flexibly and ensure the wide speed range operation. In this paper, a novel brushless HEM with permanent magnet (PM) located in rotor is further researched. By supplying specific armature currents, the sub‐harmonic component magnetomotive force (MMF) in stator MMF would be generated and utilized to realize the brushless hybrid excited operation. Firstly, the generation principle of the sub‐harmonic component is derived analytically. Secondly, during the brushless hybrid excited operation, the influence of the stator current amplitude ratio m$$ m $$ is quantitatively studied. Thirdly, based on 2D finite element analysis (FEA), the electromagnetic performance of the brushless HEM is analyzed under different operation statuses over a wide speed range. At last, the experiment is performed based on a 6 kW brushless HEM prototype machine, and the correctness of the theoretical analysis and FEA results are validated by the test. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Eddy current losses in magnets are a major consideration in the rotor design of permanent magnet synchronous motors (PMSMs). Stator design choices and the use of modern inverters with high switching frequency introduce harmonics that can contribute to significant losses in the magnets, causing the rotor to heat up. In typical PMSMs, the lack of rotor cooling can cause the magnet's performance to degrade at high temperatures and eventually demagnetize. This review examines a large number of studies analyzing magnet eddy current losses using analytical methods and finite-element analysis. In some of these studies, magnet segmentation is carried out to reduce the losses; however, their loss-reduction effects depend highly on the type of PMSM and the mix of stator harmonics. Magnet segmentation without considering these effects can, in fact, increase the magnet losses, in addition to the extra manufacturing efforts. Multiple design analysis show the influence of rotor–stator geometric features on magnet losses. Although measuring magnet eddy current losses for these motor designs is a tedious task, authors have proposed calorimetric and loss segregation-based techniques to provide validation. This paper addresses magnet loss modeling techniques, PM material considerations, magnet segmentation effectiveness, motor and stator design effects, and experimental validation to inform motor designers about the costs and benefits of rotor designs that minimize rotor losses. [ABSTRACT FROM AUTHOR]

Vernier permanent-magnet machines have been attracted more and more attention because of their high torque density. In this paper, the sensorless control strategy of the novel axially magnetized Vernier permanent-magnet (AMVPM) machine is presented. First, the inductance non-linearity is investigated under different load conditions. Second, the mathematical model is established in cooperation with the finite element method. After that, the back electromotive force based sensorless control strategy is developed according to the state equation of the motor. In the sensorless drive, the model reference adaptive system (MRAS) technique incorporated with the inductance non-linearity is used for the speed estimation. The modified control strategy not only increases the stability but also improves the dynamic response of the system. Finally, the simulation results show that the modified MRAS is of high estimation precision, and the AMVPM machine can be well controlled, and the experimental results validated the theoretical design process. [ABSTRACT FROM AUTHOR]

This paper addresses an integrated and developed approach to the design of an Axial Flux Permanent Magnet Wind Generator (AFPMWG). The proposed analytical method of design employs the size equations and precise inductance calculations simultaneously, as well as considering the mechanical constraints of the back-iron disc of the rotor. An Elitist Genetic Algorithm (EGA), such as a high capability optimization method, has been used to solve the equations and design of a wind generator with predefined rating power. The objectives of the coreless AFPMWG design process are minimizing the magnet consumption, maximizing machine efficiency, and achieving maximum sinusoidal induction voltage, considering the wind properties of the geographical area of utilization. The optimal calculation of the permanent magnet thickness is also taken into consideration in this work. The flux density distribution in all parts of the machine has been investigated for the magnetic saturation phenomenon. In this regard, special attention is paid to rotor back discs, which are made from nonlinear material with an optimum thickness. The inductance of the leakage flux of the coreless machine has been considered by parallel computation via the Finite Element Method (FEM) and analytical equations. Finally, three-dimensional and two-dimensional finite element analyses are used to validate the performance of the machine design according to the characteristics of Iran wind resources. The results show the high ability of the proposed approach in AFPMWG design and in considering the objectives and constraints carefully. [ABSTRACT FROM AUTHOR]

Variable speed, permanent magnet synchronous machines with hybrid excitation have attracted much attention due to their flux-control potential. In this paper, a design of permanent magnet axial flux machines with iron poles in the rotor and an additional electrically controlled source of excitation fixed on the stator is presented. This paper shows results pertaining to air-gap flux control, electromagnetic losses, electromagnetic torque, back emf and efficiency maps obtained through field-strengthening and weakening operations and investigated by 3D finite element analysis. Moreover, the temperature distribution of the machine was analyzed according to the fluid–thermal coupling method. The presented machine was prototyped and experimentally tested to validate the effectiveness of numerical models and achieved results. [ABSTRACT FROM AUTHOR]

Claw pole machines (CPMs) have the advantages of a simple structure and low cost; therefore, they are commonly used in electric vehicles (EV). However, the methods to improve reliability and efficiency should be studied. So, a new type of hybrid excitation claw pole machine (HE-CPM) for EV is proposed. The permanent magnet (PM) is inserted in the rotor, and the field winding is placed on the front and back ending cover. Because the hybrid flux path of the proposed machine is three-dimensional (3D) and 3D finite element analysis (FEA) is time-consuming, a 3D magnet equivalent circuit (MEC) method considering rotor position is proposed and results between 3D MEC and FEA are compared. Particle swarm optimization (PSO) and 3D MEC are combined in the optimization design of HE-CPM. The optimized results prove the effectiveness of the optimization method. Finally, the flux density distribution, electromagnetic characteristics of HE-CPM are evaluated. The thermal analysis and mechanical stress analysis are carried out. The HE-CPM prototype was manufactured. The direct current (DC) bus voltages under different excitation currents and load currents are measured and compared with those of FEA. When the armature current and the excitation current are 7 A and 4 A, respectively, the rated power and rated speed of HE-CPM are 10.28 kW and 3000 rpm, respectively. The maximum efficiency is 89%. FEA results are basically consistent with the experimental results. Accurate results and time savings can be achieved by combining PSO and 3D MEC. [ABSTRACT FROM AUTHOR]

In this paper, an analytical method for the calculation of the electromagnetic field in the airgap of a permanent-magnet synchronous machine is developed, so as to compute the torque of the machine. Such a work is applicable to different machine topologies (even for salient rotor ones), when a two dimensional approximation of the structure is possible. This analytical model can be useful in an optimization task. In the first part, the analytical method of the field computation is explained in detail, both for the magnet's field, and for the armature reaction field. The results are compared to finite elements analysis. [ABSTRACT FROM AUTHOR]

This research work is aimed at the modification of in-wheel switched reluctance motor (Outer rotor-type SRM) with minimized torque ripple for electric vehicles. The geometry of stator and rotor poles affects the torque. Variation in the stator and rotor pole geometry causes change in the torque profile. To reduce the torque ripple and to increase the average torque, modification in the stator and rotor pole shoes is presented in this article. The stator and rotor pole shoes with notches and projections are proposed with the objective of minimization of torque ripple and maximization of average torque. Electromagnetic analysis of conventional and modified in-wheel SRM is done with computer-aided design software MagNet 7.1.1. From the finite element analysis results, the average torque and torque ripple values are derived. Prototype of 8/6, 1000 W in-wheel SRM with the notches and projections is fabricated. Experimentation is performed on the fabricated machine to measure the magnetic flux linkage, current and speed characteristics of the proposed in-wheel SRM. The precise determination of magnetic flux characteristics is significant to check the machine design and to accurately predict the action of modified in-wheel SRM. Static modeling results of the fabricated machine were coherent with the experimental values. [ABSTRACT FROM AUTHOR]

This study presents a shape optimization framework that can determine the optimal rotor and stator shapes of the switched reluctance motors (SRM). The goal of design optimization is to adjust a torque profile to the target torque under the current limitation. For this purpose, the spline-based pole-shape representation and stator-fitted coil representation are implemented to precisely represent the complicated geometry of the SRM. Through linking the electromagnetic field analysis module (ANSYS Maxwell) and the electric circuit analysis module (ANSYS Simplorer), the performance of the SRM is evaluated with consideration of a high nonlinearity due to the magnetic saturation. Then, the shape optimization is extensively performed to quantitatively investigate a relation between the optimal shapes and target performance (i.e., average torque, torque ripple, and current limitation in this study). These numerical results provide an informative design guideline for determining the optimal rotor and stator shapes of the SRM to achieve a high average torque and a low torque ripple under the given current limitation. [ABSTRACT FROM AUTHOR]

Electromagnets are widely used as driving devices in industry. In this article, we describe various designs and methods of analysis for a built-in coil electromagnetic holding device based on three main design characteristics: volume, applied voltage, and suction force. Our aim is to achieve greater suction force or Gaussian value without changing the external dimensions of the frame, by varying the magnetic pole surface area, the thickness of the iron frame, and/or the electromagnetic material. We verify the design with the simulation software ANSYS Maxwell, which uses a commercial finite element method, to find the best design parameters to maximize the suction force or Gaussian value. The experimental results confirm the results of our simulation studies and demonstrate that simulations can achieve substantial reductions in cost and time over traditional trial-and-error methods. Furthermore, the experimental results indicate that electromagnetic products with bigger pole surface areas provide more suction force than electromagnetic products with smaller pole surface areas only when the applied voltage is less than 9 V. Above 9 V, smaller pole surface areas definitely result in bigger suction force. [ABSTRACT FROM AUTHOR]

In this paper, a systematic approach to achieve optimized design of interior permanent magnet machine (IPM) having novel semi-overlapping windings (NSWs) is presented. The optimization parameters have been determined individually by performing sensitivity analyses. Multi-objective global optimization is subsequently performed. Genetic algorithm (GA) approach, which is also known as "random search with learning algorithm" and an effective optimization tool used for design optimization of electric machines, is employed. IPMs equipped with integer-slot distributed winding (ISDW) and NSW are initially designed by using the geometric and operating parameters of Toyota Prius 2010 IPM. Subsequently, a time-stepping 2D finite element analysis (FEA)-based program is employed to perform the optimization and quickly evaluate the optimal solution among the thousands of design candidates thanks to the sensitivity analyses. In order to reveal the effectiveness and rapidity of the multi-objective global optimization, a comprehensive electromagnetic performance comparison between the original (with ISDWs), initial and optimal designs (with NSWs) is presented. Finally, a small IPM prototype globally optimized by using the proposed procedure is manufactured, and the FEA results have been validated by measurements. Our goals in this study is to advance the state of the art in the multi-objective design optimization of NSW IPMs by performing sensitivity analyses to reach the optimal solution quickly and to determine the most sensitive design parameters affecting the key performance characteristics. [ABSTRACT FROM AUTHOR]

Purpose: To investigate transverse vibration of the eccentric rotor in a 12/8 poles switched reluctance motor (SRM), a transverse analytical vibration model is built by finite element method (FEM) under the interaction of radial magnetic resultant and vibration displacement. External forces, including radial magnetic resultant and centrifugal force, are also derived in detail, according to the variation of airgap and current and other intermediate parameters with rotation angle. Design/methodology/approach: The transverse vibration response of the eccentric rotor including radial magnetic resultant and vibration displacement is solved by Newmark-β method, after inputting the currents of three phase windings under angle position control strategy. The basic characteristics of radial magnetic resultant and vibration displacement are reflected in time and frequency domain. Findings: The magnetic resultant vector of the eccentric rotor presents multi-petals star geometric shape. The frequency distribution of magnetic resultant relates to rotation speed, current waveform and the least common multiple of the stator and rotor teeth. However, the frequency distribution of the vibration displacement also relates closely to the first-order critical whirl speed of the rotor. When the rotor is running at certain speeds, it will display superharmonic resonance and show abundant displacement locus. Originality/value: By using this analytical model and solving process proposed in this paper, the nonlinear coupled vibration response of the eccentric rotor in SRM can be analyzed and discussed rapidly; only the stator's winding currents obtained by experiment or electromagnetic simulation is needed as input. [ABSTRACT FROM AUTHOR]

Summary: The switched reluctance motor (SRM) has the high level of vibration and noise, whose application is greatly limited in many fields. In this article, a novel stator for a SRM is designed to reduce torque ripple and is suitable for one‐directional or low‐speed reverse rotation. On the one hand, a shoe is added to the stator pole side in the rotating forward direction from the completely unaligned to the aligned position. On the other hand, a slot is set on the top of stator tooth. First, causes of vibration and torque ripple are analyzed. Second, it is indicated by the equivalent magnetic circuit (EMC) method that the air gap permeability of the model with the single‐sided pole shoe is larger than that of the conventional model in the nonoverlapping region between the stator and rotor. The influences of the angle and height of shoe on the air gap magnetic density, radial force, and torque ripple are analyzed. Third, the results from EMC method show that the radial force can be reduced by opening a slot at the top of stator pole arc. The width and depth of slot which has effect on the radial force and torque ripple are analyzed. Finally, finite element analysis results show that the decreases of 34.52% for the radial force wave peak and 43.39% for the torque ripple are achieved at the cost of a decrease of 8.54% for the average torque of the single‐sided pole and the slot model of the stator pole compared with the conventional model. Some experiments for the two prototypes verify that the torque ripple and radial force can be reduced by adopting the new model. [ABSTRACT FROM AUTHOR]

In this article, a Hybrid Excitation Synchronous Machine (HESM) is optimally designed for a specified Hybridization Ratio (HR). A new formulation of the design problem is proposed to be tackled by the Non-dominated Sorting Genetic Algorithm II (NSGA-II), while minimizing the material cost. This formulation includes a more comprehensive explanation of the key concept, HR, which considers the soft and hard saturation effects in the HESM design. The HESM model is based on a 3D nonlinear Magnetic Equivalent Circuit (MEC). For faster convergence, the number of design variables is reduced using two statistical analyses, namely Analysis of Level and Analysis of Variance (ANOVA). A HESM is optimally designed for HR = 0.5 and validated by a commercial Finite Element Analysis (FEA) software. [ABSTRACT FROM AUTHOR]

Hybrid excited (HE) machines have the synergies of high torque density and high efficiency of permanent magnet (PM) machines and excellent flux controllability of wound-field machines. The PMs and field coils (FCs) coexist in HE machines to provide excitations simultaneously, and can be coupled either in series or parallel. The topologies of HE machines are very diverse, which bring challenges in the selection and design of HE machines. Based on the partitioned stator (PS) platform, a pair of series and parallel HE machines having similar structures and PM usage are evaluated and compared to identify their merits and demerits. With the help of finite element analysis, the flux regulation, energy conversion capability, parasitic effects and irreversible demagnetization of the two kinds of the HE machines are comprehensively investigated and the guidance to the machine design is provided. A pair of prototypes are fabricated and tested to validate the analyses. [ABSTRACT FROM AUTHOR]

Summary: The flux switching permanent magnet (FSPM) motor is relatively a new topology of the permanent magnet (PM) motors, which both PM and armature winding are placed at the stator. This feature leads to more robust design, better heat dissipation, and a proper option for a wide range of industrial applications. The critical part of the development of FSPM motor is the design optimization of the structure to improve the electromagnetic performance of the motor. In this article, first to reduce the computation time and required memory of the optimization procedure, the multiobjective sensitivity analysis based on design of experiment is performed to specify the most effective parameters on the objectives. Then, the initial samples data of the optimization procedure is obtained by 2D finite element method (FEM) model of the FSPM motor, which is validated by the prototype of the motor. Furthermore, based on FEM results the multilayers perceptron artificial neural network for the approximation of relation between design variables and objectives is implemented. Finally, using the nondominated sorting genetic algorithm‐II, the optimization procedure of the FSPM motor is done. The accuracy of the presented optimization procedure is validated by a comparison of the initial prototype and final design of the motor. [ABSTRACT FROM AUTHOR]

Summary: This article proposes an analytical model based on magnetic equivalent circuit for a transverse‐flux permanent magnet machine (TFPMM). Taking into account, the magnetic saturation in iron parts of the machine, the proposed method is capable of calculating the performance parameters of the machine such as flux density, flux linkage, cogging torque, back‐EMF and its harmonic contents with high accuracy. In order to evaluate the accuracy of proposed model, performance parameters of a TFPMM obtained analytically are compared to those achieved by three‐dimensional finite element method (3‐D FEM). A preliminary optimisation based on the proposed analytical modelling is presented to show suitability of the approach in performance parameter optimisation of TFPMM. In comparison to 3‐D FEM, the proposed model introduces less computational time, while the accuracy remains approximately the same. The results show that the proposed approach can be used during design stage and optimisation of the transverse flux machine as a simple, fast and accurate alternative to the precise but time consuming and tedious 3‐D FEM. [ABSTRACT FROM AUTHOR]

The paper details the design optimisation and comparison of two different rare-earth permanent magnet flux-switching machines (PM-FSMs)—12/10 and 12/14—for geared medium-speed wind power generators. The focus is mainly on trade-offs in the performance of these two machines at 10 kW and 3 MW power levels, with highlights on the multi-objective evolutionary optimal performance of small-scale to utility-scale wind turbines. Based on finite element analyses (FEA) and multi-objective design optimisation (MDO), different streams of optimal solutions are obtained and studied. As an indication of the potentials of the proposed PM-FSM wind generators, even for rare-earth-free concepts, the 3 MW designs portray significantly improved torque density thanks to the fixed rotor speed considered at both power levels, and also, smaller torque ripple profiles are conceived due to differences in the calculated saliency ratios, compared to their 10 kW designs. Another finding is based on the nonlinearity of the MDO process on the objective performance of the different machine topologies at the different power levels, which was necessitated by the optimal behaviour of certain design variables such as the split ratio, slot opening width, current density and PM width. Uncharacteristically, the results also reveal possibilities for higher efficiency in 12/14 machines compared to the 12/10 machines, due to positive relationships approximated from general evaluations conceived in the MDO search space in the former, for the split ratio and current density when plotted against the active mass. Lastly, a comparison between 2-D static and 3-D transient FEA processes on some selected benchmarks displayed good agreement. [ABSTRACT FROM AUTHOR]

IPM (Interior Permanent Magnet) motors produce torque based on two different mechanisms. The first of them is permanent-magnet torque, which is generated by the flux linkage between the PM (Permanent Magnet) rotor field and the electro-magnetic field of the stator. It is the same torque as produced by SPM (Surface Permanent Magnet) motors, however, IPM designs produce another force known as reluctance torque. The second one, the shape and location of the slots in the rotor laminations are designed to channel magnetic flux so that even if the slots were left as air gaps, the rotor would experience a force to align the magnetic flux lines with those generated by the stator coils. IPM motors are now very popular in industrial and military applications by providing high power density and high efficiency compared to other types of motors. This paper presents the use of finite element method harmonic analysis for investigation of IPM motor acoustics noise. This method is useful for DC (Direct Current) motor designs in many industrial and military applications. [ABSTRACT FROM AUTHOR]

In this paper, an U-shape flux barrier rotor concept for a hybrid excited synchronous machine with flux magnetic bridges fixed on the rotor is presented. Using 3D finite element analysis, the influence of axial flux bridges on the field-weakening and -strengthening characteristics, electromagnetic torque, no-load magnetic flux linkage, rotor iron losses and back electromotive force is shown. Three different rotor designs are analyzed. Furthermore, the field control characteristics depending on additional DC control coil currents are shown. [ABSTRACT FROM AUTHOR]