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Three-phase linear synchronous actuators play a pivotal role in precision motion control applications such as lithography machines and laser material processing stages. Achieving superior tracking performance is paramount in the design of motion control systems, prompting the utilization of advanced control algorithms. In this study, a novel approach is presented to enhance the tracking capability of a three-phase permanent magnet actuator by introducing a predictive field-oriented control system. The primary contribution of this paper lies in the comprehensive design and implementation of the predictive field-oriented control system. Initially, actuator modeling is conducted in the rotating reference frame (d–q frame) and finite element analysis is performed to determine key electrical quantities, including magnetic flux densities and inductances. To address the challenges posed by time-varying sinusoidal electrical signals, a field-oriented control methodology is proposed. Notably, the novelty of this work is underscored by a distinct emphasis on the predictive control strategy employed in the system. The predictive controller is implemented on a 32-bit ARM Cortex microcontroller, showcasing the practical viability of the proposed approach. Experimental results substantiate the effectiveness of the proposed method in achieving precise trajectory tracking. This paper contributes to the field by providing a rigorous analysis of a three-phase permanent magnet actuator and introducing a predictive field-oriented control system. The methodology outlined here enhances tracking capabilities and signifies a substantial advancement in the broader landscape of precision motion control systems. Thus, this work adds valuable insights to the existing body of knowledge in the domain, while offering a notable contribution to the field. [ABSTRACT FROM AUTHOR]

The permanent magnet claw pole machine (PMCPM) with soft magnetic composite (SMC) cores has shown better performance than the traditional transverse flux machine, and its performance can be improved by developing its stator with hybrid silicon sheet and SMC cores, and this kind of PMCPM is named as HPMCPM. Due to its complex 3D magnetic structure, analyzing its performance by using the traditional finite element method (FEM) is time-consuming. To overcome this constraint, this paper proposes a magneto-electric-thermal coupling network (METCN) model with bidirectional data transmission to calculate the electromagnetic performance and temperature distribution and the calculation results are verified by the FEM method and experimental measurement results. Compared with the 3D FEM, the proposed METCN method has the advantage of fast calculation speed and similar accuracy. [ABSTRACT FROM AUTHOR]

In this paper, three typical permanent magnet machines for All-Electric aircraft propulsion are designed, optimized and compared. Firstly, the necessary performances are determined based on the requirements of high power/torque density and an aircraft with a maximum takeoff weight of 1500 kg. The initial structures of interior permanent magnet (IPM) synchronous machine, vernier permanent magnet (VPM) machine and flux-switching permanent magnet (FSPM) machine are designed with identical stator outer radius and rotor shaft length. Then, parametric sensitivity analysis and multi-objective particle swarm are combined as an optimization methodology to optimize these machines. Based on the finite element analysis, the electromagnetic performances such as no-load airgap flux density harmonic spectrum, cogging torque, average output torque, losses, efficiency and power factor, etc., are generally compared and analyzed. Subsequently, the discussions are carried out, where the strength and weakness of these three machines are concluded and the future prospects are suggested. Finally, it is concluded that if effective measures are implemented to reduce the permanent magnet eddy current loss and improve the power factor, the VPM machine would be the most suitable choice among these machines for All-Electric aircraft propulsion. [ABSTRACT FROM AUTHOR]

In this paper is presented a two-dimension analytical model for linear permanent magnet inner armature double-sided synchronous motors (LPMIADSSMs). The flux density in all areas of the proposed machine is calculated based on the sub-domain method. According to this method, the machine areas are divided into eleven sub-regions such as first external, first mover, first PM, first air gap, first winding, stator, second winding, second air gap, second PM, second external and second mover, which sign as FE, FR, FP, FAG, FW, S, SW, SAG, SP, SE and SR. To find the flux density equations, it is mandatory to solve the extracted Maxwell equations and apply the boundary conditions between each two sub-regions, which lead to find the unknown coefficients for flux density in each sub-region. In addition, the influences of magnetization patterns, i.e., parallel, ideal Hal Bach, 2-segment Halbach and bar magnet in the shifting direction of the flux distribution and armature reaction (AR), are investigated. To validate the obtained results, the proposed model results are compared with those obtained from finite element method (FEM) and Maxwell software. [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]

In order to reduce the cogging torque of a symmetrical V-type line-start permanent magnet synchronous (LSPMS) motor, this paper proposes a multi-objective optimization method based on the combination of design parameter stratification and response surface methodology (RSM). The optimal solution to the RSM model is acquired using the max–min ant algorithm. The permanent magnet width, pole opening angle, stator slot width, rotor axial length, and rotor tooth width are selected as optimization variables. The cogging torque and average torque are the optimization objectives. Finite element method (FEM) results show that the cogging torque is reduced by 71.5%, the torque ripple is reduced by 65.6%, and the average torque is improved by 12%. Finally, the effectiveness of the algorithm is verified with simulation results. [ABSTRACT FROM AUTHOR]

The permanent magnet electrodynamic suspension (PMEDS) owns the promising application prospect, due to its simple structure, low cost and reliable load capacity. However, the underdamping of the PMEDS system is still a challenge in engineering applications of transportation. This paper proposes a passive damping method and its implementation structure to improve the underdamping characteristics. This method utilizes the inherent magnetic leakage of on-board magnets technically. The principle of passive damping and its implementation structure is introduced in detail. And the kinetic models of ordinary and improved structure are established based on the topology graph. Besides, the magnetic field and the electromagnetic force involved in the kinetic models are analyzed, and the numerical analysis method of the drag force is verified by the high-speed test rig. Furthermore, the performance of passive damping is verified by finite element method (FEM) and the time-domain response analysis. The results show that the improved damping structure can effectively suppress vibration and improve the dynamic stability of the PMEDS system. It is beneficial to the engineering application of the PMEDS in the future. [ABSTRACT FROM AUTHOR]

This paper proposes a new design method for sleeve thickness and interference based on a multi-dimensional visualization algorithm that overcomes difficulties in solving. The contact pressure between the rotor core and the permanent magnet, the maximum equivalent Mises stress of the permanent magnet, and the maximum equivalent Mises stress of the sleeve are selected as the optimization objectives. The stress limit strength of the permanent magnet and sleeve are taken as constraints, and the sleeve thickness and interference are selected as decision variables. Then the multi-dimensional visualization algorithm is used to find the optimal region of sleeve thickness and interference. Finally, the design solution is validated by the finite element method. The results show that the design method proposed in this paper can obtain the optimal region of sleeve thickness and interference with the characteristics of a simple solution process and intuitive results. [ABSTRACT FROM AUTHOR]

In order to solve the problem of the large moment of inertia of the existing rotating electromagnetic shock absorber for armored vehicles, a new lightweight rotor adaptive electromagnetic shock absorber (LR-AESA) is proposed in this paper. The LR-AESA consists of the left and right symmetrically distributed stators, a rotor in the middle and excitation coils. Secondly, based on the equivalent magnetic circuit method (EMC) and the Ampere loop theorem, and the interaction of the reaction magnetic fields between adjacent eddy current rings and the nonlinear effect of the interaction between the eddy current field and the original magnetic field are further considered, the air gap magnetic field distribution of the LR-AESA of the 10# steel rotor and the copper rotor at different speeds is derived, and the analytical expression of the damping torque is obtained. Finally, the validity of the analytical model was verified by comparison with results from the 3-D finite element method (FEM). The results show that the LR-AESA of the two material rotors can meet the requirements of technical indicators, but in the full speed section (200 ∼ 2000 rpm), the copper rotor has the advantage of a wider range of the damping torque adjustment. [ABSTRACT FROM AUTHOR]

As permanent magnet claw pole machine (PMCPM) is designed with a complex 3D magnetic structure, the 3D finite element method (FEM) is commonly used for its accurate performance analysis. However, using 3D FEM will consume a long time in the initial design stage. Its analysis time can be saved greatly by using the analytical method (AM) or equivalent magnetic circuit method (MCM), however, the obtained performance is not accurate and some performance even cannot be obtained if only one of these methods is used. To overcome the above constraints, this paper proposes a calculation method that combined analytical and equivalent magnetic circuit method (AMCM) to calculate the main electromagnetic performance of PMCPM quickly. Its calculated results are verified by corresponding results obtained by using the 3D FEM. It can be seen that the proposed AMCM is effective for calculating the main electromagnetic performance and designing of PMCPM. [ABSTRACT FROM AUTHOR]

To improve the performance of low-speed large-torque direct drive systems in limited space, an axial field flux-switching composite machine (AFFSCM) is proposed in this paper. The AFFSCM is composed of an axial field flux-switching permanent magnet machine (AFFSPMM) and magnetic gear. Therefore, it has the advantages of a compact structure, a large power/torque density, and a wide speed regulation range. First, the topology and magnetic modulation mechanism of the AFFSCM are investigated in detail. Then, the harmonic components of the inner/outer air-gap flux density are analyzed before and after the regulation of the rotary magnetic modulation ring. Based on this, the coupling conditions of the inner/outer air-gap magnetic field are deduced. Then the AFFSCM is initially designed, a three-dimensional finite-element model of the AFFSCM is built, and the electromagnetic performances are analyzed by the finite-element method, including the flux density of the inner/outer air-gap, the speed, the static torque, etc. Next, the cogging torque of the AFFSPMM is analyzed and optimized based on the magnetic modulation mechanism to suppress the torque ripple of the AFFSCM. Finally, an 800 W prototype is constructed and related experiments are done to validate the AFFSCM. [ABSTRACT FROM AUTHOR]

This paper presents a study of bidirectional permanent magnet excited machine (BPMEM) based on the study of field-modulation permanent magnetic gear machine (FPGM). The BPMEM structure includes the installation of consequent-pole permanent magnets (PMs) on both the stator and rotor sides of the FPGM so that the stator and rotor can be bidirectionally excited to increase the working airgap flux density amplitude, reduce the flux leakage between poles, and increase the torque density. Therefore, the paper first analysis the influence of different airgap structures and PM arrangements on the airgap flux density and studies the winding slot–pole combination and the resulting working flux density harmonics to analyse the electromagnetic torque generation mechanism. By using the finite element analysis (FEA), the quantitative analysis and comparison of the FPGM, slot-wedge-less FPGM (SWL-FPGM), consequent-pole FPGM (CP-FPGM) and BPMEM verify the superiority of BPMEM in improving electromagnetic torque. In addition, the paper also studies the key performance of BPMEM's overload capacity, power factor and flux-weakening capability. Finally, no-load and independent load experiments are carried out on the FPGM prototype to verify the correctness of the FEA model and analysis method of the machine in this paper. [ABSTRACT FROM AUTHOR]

Due to its unique characteristic of non-contact torque transmission between its permanent magnetic rotor and conductor rotor, permanent magnet eddy current coupling (PMECC) is preferable in transmitting torque from the outside to the inside of a sealed container, which can effectively avoid the tricky problem of dynamic seals. To mix non-uniform liquid solutions or gas mixtures in sealed containers more effectively, a sinusoidal torque is also required. Thus, permanent magnet eddy current coupling with a slotted conductor is proposed in this paper, which can adaptively output sinusoidal torque under a real-time load when the input rotational speed is constant. Based on the equivalent magnetic circuit method, an analytical model for calculating torque is proposed. When establishing the equivalent magnetic circuit model of the PMECC, the radial magnetic flux leakage circuit is added to the equivalent magnetic circuit diagram, and the cross-sectional shape of the eddy current region is equivalent to an octagon, which simplifies the torque calculation process. The analytical model is verified by finite element method (FEM) simulation and experiments. According to a comparison, the peak and lowest values of output torque obtained by the experiments, the analytical model, and the FEM simulation are consistent. The output torque waveform obtained by the analytical model and FEM simulation are also consistent. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNT), CNT–aluminum (CNT–Al), and CNT–copper (CNT–Cu) composite wires have shown remarkable electrical and mechanical properties for developing windings of single-phase induction motor. A quest has been made that if these advanced carbon nanomaterials can outclass commonly used electrical wire metals to significantly leverage electrical machines. However, these advanced materials are still in laboratory stage and most material properties are not yet experimentally reaching to their expectations. Therefore, there is need to understand the potential of these nanomaterials for electrical machines and the numerical analysis of the performance of electrical machines with various advanced novel carbon nanomaterials is still a challenge. This paper presents a comprehensive study to compare the performance of a single induction motor with its stator and rotor made with different winding materials. In doing so, the traditional copper and aluminum rotor and stator coils have been replaced by windings made of pure CNT yarn, CNT–Al, and CNT–Cu wires. A 2-D induction machine model was developed for the simulation study conducted in COMSOL Multiphysics finite element-based software. General-purpose sizing and power equations were utilized during the computation. The simulated results of flux distribution, air-gap flux density, torque, and corresponding output power were used as criteria to determine the highest quality solution. The simulation results revealed that using CNT–Cu and CNT–Al wires as machine winding can achieve 25.9% and 16.8% higher efficiency, respectively, than using CNT wires. The motor torque from the proposed finite element model was validated against the experimental results under identical speed and input voltage, and an error of 5.9% suggests that the model can be used to predict the motor performance with reasonable accuracy. [ABSTRACT FROM AUTHOR]

Hybrid excited flux switching linear machines (HEFSLM) are attracting attention in rail transit applications due to their high thrust force density, power density, and efficiency. more importantly, their flux controlling ability gives them an edge over permanent magnet machines, which possess constant flux. This paper investigates a modular mover HEFSLM (MMHEFSLM) with concentrated armature and field windings. The concentrated windings result in thrust force ripples but reduce the copper losses. The modular structure of the mover helps in achieving fault-tolerant ability. The volume of PM is significantly reduced, which is rare-earth material and its price is rising progressively. JMAG in-built genetic optimization is utilized to refine the leading CAD parameters thereby improve performance compared to the initial design. The fault-tolerant ability of the proposed machine is verified by the phase's inductance calculation. Finally, based on the electromagnetic performance, the proposed MMHEFSLM is compared with conventional design in the literature. [ABSTRACT FROM AUTHOR]

In this paper, the authors propose a flexible automatic procedure for optimizing multiphase single-layer winding end-connections by the differential evolution algorithm. By using the winding distribution in slots as a predefined input, connections between phase conductors located in different slots are determined to minimize the winding average coil pitch and to simultaneously maximize the number of coils with identical coil pitch. For an adopted geometrical shape and number of turns of individual coils, minimization of winding average coil pitch results in minimized end-connection length, winding resistances, end-leakage inductances, winding mass and copper losses, while machine efficiency and power factor are maximized. However, maximizing the number of identical coils simplifies and speeds up the process of coil fabrication during machine assembly, but potentially leads to higher average coil pitch. The proposed method is applied to single-layer windings with different slot, pole and phase combinations, where it is proven that the method automatically provides end-connection arrangements which are better or equal in terms of copper usage and simplicity of fabrication than the ones found in the literature. Verification is conducted by comparing overall performance of several Rotor Permanent Magnet Flux Switching motors with different stack lengths, outer diameters and optimized end-windings by means of 2D finite element analysis and 3D analytical approach. The proposed method is conceived as an automatic tool for optimization of single-layer winding end-connections during comprehensive electrical machine design optimization. [ABSTRACT FROM AUTHOR]

High temperature superconducting (HTS) maglev transportation has provided a new development direction for high-speed and ultra-high-speed rail transit. In order to promote the development of HTS materials in this area, the dynamic response of the vehicle superconductor under an alternating magnetic field with high frequency is well-worth studying. However, limited by some experimental conditions and other factors, the effective modelling method becomes an indispensable and cost-effective tool to predict the electromagnetic properties of the superconductors. In this paper, based on the single-peaked permanent magnet guideway (PMG)-HTS bulks maglev configuration, the modelling using three different E-J relationships include the power law model (PLM), the flux flow and creep model (FFCM), and the flux flow model (FFM) are compared. Results indicate that the PLM has the highest computational efficiency and good reliability. Then, using the PLM, we further study the dynamic response of the HTS bulks over a Halbach-typed PMG under higher vibration frequencies. The effect of the magnet failure in the middle of the PMG on the levitation system is also discussed. A finite element method is applied with the H formulation. The moving mesh is used to realize the relative displacement between the PMG and HTS bulks. To investigate the temperature rise and the AC loss inside the HTS bulks, the Heat Transfer module is coupled. Results show that the temperature inside the HTS bulks will decay exponentially with time if the magnitude and frequency of the external magnetic field do not continue to increase. This work can provide some references for the future practical applications of the high-speed HTS maglev. [ABSTRACT FROM AUTHOR]

Double-turbine systems offer a higher capability of wind energy conversion compared to single-turbine systems. Therefore, in order to improve the performance of double-turbine systems and eliminate mechanical gearbox systems by utilizing the direct-drive concept, a new direct-drive generator design is required. In this paper, the structure of a novel spoke-type permanent magnet induction generator (STPMIG) exploited in double-turbine wind systems is investigated, and the performance and relationships of the proposed generator with and without iron bridges are studied. The proposed generator consists of a stator, and two concentric permanent magnet and squirrel-cage rotors, in which the voltage induction in the stator windings is possible only by the permanent magnet outer rotor. Although utilizing the permanent magnet rotor with iron bridges enhances the mechanical strength, the leakage flux increases, which leads to the reduction in the generator output power. In order to decrease the leakage flux and improve the output power of the proposed generator, the bridgeless outer rotor structure is preferred over the rotor with iron bridges. The bridgeless structure offers lower leakage flux, higher efficiency, and lower voltage regulation in comparison with the bridged structure. Furthermore, the novel structure of double-rotor STPMIG allows rotors to rotate independently at different speeds without employing additional rings and brushes, regarded as considerable merit for double-turbine wind systems. Finally, a 250-W bridgeless double-rotor STPMIG exploited in double-turbine systems is constructed and tested to verify the finite element analysis (2D-FEA) results. [ABSTRACT FROM AUTHOR]

This paper investigates two rotor configurations for five-phase permanent magnet assisted synchronous reluctance motor (PMASyncRM) in which the Ns/Np ratio remains equal to the number of phases and the minimization of torque pulsation, mainly cogging torque (Tcog), is desired. The proposed initial models have three layers of flux barriers per pole and are categorized as either A-type or B-type. The A-type has three layers of flux barriers where two of them are filled with PMs and the third one is left empty. The B-type has PMs inserted into all three layers of the flux barriers. Accordingly, based on torque analyses of the proposed models, the candidate that produces the lowest Tcog is selected for in-depth study. Thus, a sensitivity analyze is performed considering the length of the stator slot opening (Lso), the length of the air-gap (Lg), and the length of the 3rd flux barrier (Lb) as analysis parameters that are simultaneously taken into account. The outputs demonstrate that for the resultant values of Lso-Opt, Lg-Opt, and Lb-Opt, the value of Tcog declined considerably when compared with that of the initial motors. Finally, the optimized model is studied using 2-D finite element analysis (FEA) and the torque characteristics were compared with the initial model. The obtained results show that the optimized model provides much lower torque vibrations. [ABSTRACT FROM AUTHOR]

Superfine grinding technology is widely used in various industries, such as food, medicine and chemistry. Traditional superfine grinding methods have some problems in temperature rise, material pollution and environmental pollution. Therefore, a new type of superfine grinding technology, impeller-type turbulence mill (ITTM) driven by a high-speed permanent magnet machine (HSPMM), is studied in this paper to overcome these problems. Firstly, the design processes of the HSPMM and ITTM are proposed. On this basis, the mechanical and electromagnetic losses of the HSPMM are calculated using analytical method and finite element method (FEM), respectively. The power losses are used as the heat source to calculate the temperature field of the HSPMM. Considering the axial and radial temperature gradient, the ITTM rotor thermal stress is investigated by the thermal-stress coupling method. In addition, the computational fluid dynamics (CFD) method is utilized to analyze the superfine grinding mechanism of the ITTM. The HSPMM and ITTM are fabricated and tested to verify the design and analysis. The experimental results show that the ground materials reach the sub-micron level, and the temperature rise of the ground materials is only 30 °C. Compared with other superfine grinding technologies, the developed ITTM has a superior comprehensive performance. [ABSTRACT FROM AUTHOR]

Energy efficiency is primary target for electric motor designers. The Eddy current losses can cause deterioration of permanent magnet machines magnetic properties and increase rotor temperature. Therefore the rotor eddy current loses can decrease efficiency of permanent magnet brushless DC (PM BLDC) motors. Permanent magnets when designed with axial segmentation help reduce the eddy current losses. This paper presents an investigative study on calculating eddy current losses of in-wheel permanent magnet brushless direct current motors and the effect of segmented axial direction magnets on the efficiency of these motors used in light electric vehicle. In this study in-wheel PM BLDC motor has been designed and analyzed on with slot/pole combinations 24/20, 36/30, and 42/36, that the motor is rated power of 4 kW at rated speed of 1500 rpm. Finite Element Method (FEM) is used to carry out numerical analysis for an accurate result. The magnet losses and efficiency are calculated for segmented magnets with different quantity of magnets in the axial direction. Changing the number of axial magnet segment from 1 to 20 causes approximately 1% increase in the efficiency. Following the change in number of axial magnet segment, the shaft power values increment is about 40 W, while shaft torque is between 0.25 and 0.30%. [ABSTRACT FROM AUTHOR]

This paper proposes a two-phase radial flux brushless DC motor comprising a rotor decorated with hybrid permanent magnet (PM) material, i.e., rare-earth NdFeB magnets combined with ferrite magnets. The rare-earth NdFeB magnets are used on the surface, and ferrite magnets in the spoke-type configuration. The combined surface and spoke-type topology are used to improve the output torque as well as to protect magnets of different grades against irreversible demagnetization. The motor is operated using the only-pull drive technique, which allows the use of thin magnets in the motor without the effect of irreversible demagnetization. The electromagnetic performance of the proposed motor is compared with those of a two-phase surface-type PM motor and the spoke-type motor, all driven by the only-pull drive technique. Furthermore, the operating point of the ferrite magnets is analyzed using finite element analysis to confirm the demagnetization endurance of the proposed motor. [ABSTRACT FROM AUTHOR]

In this paper, a novel mechanical flux-adjusting interior permanent magnet (MFA-IPM) motor is proposed. The key is to employ an additional mechanical flux-adjusting (MFA) device attached to one side of the rotor, which can achieve flexible adjustment of the air-gap flux and obtain a wide speed range. This system with appropriate gears uses centrifugal force to set the cylindrical PMs in a required position. The topology and working principle of the MFA-IPM motor are introduced. Then, the dynamic performance prediction between the deformation length of spring and the rotation angles of PMs is obtained by the dynamic simulation. Moreover, the electromagnetic characteristics of the proposed MFA-IPM motor and a conventional IPM motor are analysed and compared based on finite element analysis, including no-load performances, inductances, electromagnetic torque, flux-weakening ability and speed range, as well as demagnetization evaluation. Finally, a prototype MFA-IPM motor is fabricated and tested. Both the simulation and experimental results indicate the validity and feasibility of the MFA-IPM motor. [ABSTRACT FROM AUTHOR]

This paper presents a framework for the simultaneous application of shape and topology optimization in electro-mechanical design problems. Whereas the design variables of a shape optimization are the geometrical parameters of the CAD description, the design variables upon which density-based topology optimization acts represent the presence or absence of material at each point of the region where it is applied. These topology optimization design variables, which are called densities, are by essence substantial quantities. This means that they are attached to matter while, on the other hand, shape optimization implies ongoing changes of the model geometry. An appropriate combination of the two representations is therefore necessary to ensure a consistent design space as the joint shape-topology optimization process unfolds. The optimization problems dealt with in this paper are furthermore constrained to verify the governing partial differential equations (PDEs) of a physical model, possibly nonlinear, and discretized by means of, e.g., the finite element method (FEM). Theoretical formulas, based on the Lie derivative, to express the sensitivity of the performance functions of the optimization problem, are derived and validated to be used in gradient-based algorithms. The method is applied to the torque ripple minimization in an interior permanent magnet synchronous machine (PMSM). [ABSTRACT FROM AUTHOR]

This paper describes a method to reduce the torque ripple for the Wound Field Synchronous Motor, which does not use a permanent magnet. When a WFSM is used in an Integrated Starter Generator system, it must have a higher power density than other automotive motors in order to satisfy the size constraints and required power. An increase in the power density creates a magnetic flux saturation in the rotor, and this soon becomes the cause of an increase in the torque ripple of motor. An increase in the torque ripple can degrade the Noise Vibration Harshness characteristics of automotive by creating vibration and noise in the engine start-up mode, in which the maximum torque is generated in an ISG system. This paper proposes a method of reducing the torque ripple via a design that uses a flux barrier model in the WFSM's rotor. The Response Surface Method is used to optimize the flux barrier model, and Finite Element Method is used to to verify the torque ripple reduction. [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]

In this paper, a low-cost high-performance axial flux Vernier machine (AFVM) with soft magnetic composite (SMC) cores and ferrite magnet is proposed, analyzed and optimized. By cooperating with spoke magnet rotor configuration and 3D magnetic flux stator structure, the proposed AFVM can output higher torque compared with the traditional permanent magnet machine though low-cost low-energy-density ferrite magnet and low-permeability SMC material are adopted. The main electromagnetic topology and operation principle of the proposed AFVM are introduced; then, its main dimensions are investigated and optimized by using sequential optimization method. Moreover, a new multilevel Taguchi design optimization which is an improvement of multilevel optimization is proposed for the torque and power factor optimization. Lastly, its main performance of AFVM optimized by the sequential optimization method and multilevel Taguchi design optimization method has been compared with a normal axial flux machine in terms of torque ability, power factor and efficiency based on 3D finite element method. [ABSTRACT FROM AUTHOR]

Vernier permanent magnet (VPM) machines have been widely used in the last two decades due to their high torque density resulting from their magnetic gearing effect. In this paper, we present a new design of VPM machine with higher efficiency and power/weight ratio than their conventional counterparts. The proposed design is a combination of discrete-pole and hybrid-pole VPM machines, which incorporates the attractive characteristics of both types to improve the distribution of air-gap flux density and reduce construction costs. The arrangement of the magnets in the stator is spoke type, and their magnetization is peripheral. In order to determine the performance characteristics of the proposed machine, an analytical model based on the subdomain method is presented. The proposed method employs a quasi-Cartesian coordinates system to express the Laplace's and Poisson's equations, as well as to determine the solution for each region. Then, the solution of the equations is written in the form of hyperbolic functions and the mathematical expression of the coefficients of the equations will be simpler. To validate the proposed analytical model, a Vernier machine is designed and fabricated and the results of the experimental experiments are compared with numerical (machine simulation in finite element analysis software) and analytical results. The comparison of these results shows that the proposed model is highly accurate. [ABSTRACT FROM AUTHOR]

This paper deals with analytical design, electromagnetic field analysis and parametric sensitivity analysis of an external rotor permanent magnet-assisted synchronous reluctance motor (PMASynRM). In this work, parametric sensitivity analysis of rotor geometry is performed to obtaining the minimum torque ripple and maximum electromagnetic torque with employing numerical analysis based on two-dimensional finite element method (FEM). In order to determine the optimum operation effect of geometry parameters like the q axis insulation ratio and the flux barrier arm angle for the proposed machine with three barriers is investigated and sensitivity of structure for rotor geometrical variation is presented. The studied machine in this work is a three phase, six pole, external rotor PMASynRM, which is designed by analytical approach and analyzed to obtain the maximum torque and minimum torque ripple based on a parametric sensitivity analysis approach. The obtained results from the FEM-based sensitive analysis and electromagnetic field analysis confirm the analytical design procedure for the proposed PMASynRM. [ABSTRACT FROM AUTHOR]

Axial field machines are available in a wide range of configurations. It has flexible design restrictions. Several research efforts were performed to discover machine performance and design horizons. However, the common design process of axial field machines depends on numerical field analysis, due to the lack of trusted and generalized analytical and/or empirical formulas especially for field distribution. This paper aims to present the essential analytic formulation for dimension selection. In addition, it provides the normalized relations between dimensions and airgap flux density using 3D-FEM as an alternative for empirical formulas. The paper describes a design procedure for coreless stator axial flux permanent magnet synchronous machine. Definite equations are derived to help the designer select the proper number of PM poles and concentrated coils to get balanced multi-phase voltage out of the generator. Moreover, the paper defines the necessary limitations of the span of the concentrated coil for a certain pole pitch to reduce the harmonic content of the output voltage waveform. The paper proposes a new approach for selecting the dimensions of the magnetic circuit using proposed data curves instead of struggling with the 3D-FEM along with its high time consumption and the need for high computational power. The loss calculations and the armature reaction are also investigated as a performance analysis criteria for the designed generator. The paper investigates the design for small-scale wind applications. The design procedure is validated using both 3D-FEM simulations and experimental results. The results show the consistency of the proposed procedure. The procedure is described and applied for a certain configuration and materials. However, it is solely extendable to several other configurations. [ABSTRACT FROM AUTHOR]

This paper proposes a new topology of hybrid flux machine (HFM) which combines the advantage of longitudinal and transverse flux machines. In the proposed topology, flux in the stator core is transverse, and flux in the rotor core is longitudinal. Unlike the transverse flux machine (TFM), it has an equal number of stator and rotor poles for better utilization of the permanent magnets. Further, the single magnet layer per phase design simplifies the rotor construction. Design of the HFM, along with the derivation of average torque, is presented. As the proposed hybrid flux machine is a modified configuration of TFM, it is compared with two different topologies of TFM (with and without pole shaping) using finite element analysis. It is found that HFM can produce the same torque of TFM with 32% reduced magnet. [ABSTRACT FROM AUTHOR]

The ratio between rotor poles and stator winding poles plays a deciding role in the performance of Vernier machines. Therefore, it is very important to analyze the effect of pole ratio on the electromagnetic torque performance of permanent-magnet Vernier machine. Dual-airgap spoke-type permanent-magnet Vernier machines (PMVMs) are becoming popular due to their low speed and high torque characteristics in the direct drive applications. This paper presents the effect of pole ratio on the performance of dual-airgap spoke-type PMVM. The performance parameters such as torque ripple, average torque, torque density and efficiency are analyzed by the variation of design parameters such as stator and rotor pole numbers and winding pole numbers, while keeping the same outer dimensions, similar magnet volumes and same airgap lengths in all the models. The electromagnetic torque characteristics are analyzed with the variation of pole ratios until the model reaches the maximum torque performance at a specific combination of rotor and stator poles. 2D-finite element method is used to analyze the performance of the model and verify the effect of pole ratio on the torque performance of dual-airgap spoke-type PMVM. [ABSTRACT FROM AUTHOR]

This paper aims to provide a smart design to improve the efficiency of surface permanent magnet synchronous motor. An efficient design strategy involving penalty approaches are considered for extracting all the possible parameter combinations and the solutions in the infeasible region. We compare the performance of tree heuristic optimization algorithms and six penalty methods. The heuristic optimization algorithms are: particle swarm optimization, differential search algorithm, and tree seed algorithm. The penalty methods are: three of which are static penalty approaches, two of dynamic penalty approaches, and Deb's rule. Besides, the optimized motor design is tested with finite element analysis. Two conclusions were drawn from the experiments. First, heuristic algorithms using penalty approaches had significantly better performance compared to standard and popular heuristic algorithms. This emphasizes the importance of using heuristic algorithms with penalty approaches in SPMSM design optimization. Second, the compatibility of design optimization and numerical analysis results are acceptable and highly satisfactory for surface permanent magnet synchronous motor design. According to the analytical design, a 4% improvement in efficiency was achieved with the proposed approach. [ABSTRACT FROM AUTHOR]

For permanent magnet synchronous motors (PMSMs) without sufficient design optimization, it is necessary to inject current harmonics to suppress torque ripple. Due to the influence of magnetic saturation, the current harmonics for torque ripple suppression changes with the electrical loads. Based on an existing analytical torque model of a PMSM considering spatial harmonics and magnetic saturation, this paper established a torque harmonic coupling model through a Taylor expansion and a harmonic balance method. Then, based on the torque harmonic coupling model, current harmonic selection for torque ripple minimization was proposed. The validity of the torque harmonic coupling model and current harmonic selection was verified by a finite element analysis (FEA) and experiments on a laboratory PMSM drive system. [ABSTRACT FROM AUTHOR]

This paper presents the optimal design and performance analysis of a novel synchronous reluctance motor with outer rotor for determination of the effect of the rotor pole shape on the machine's performances. The investigation has been made in order to find the possible ways to improve the power factor with refining the rotor geometry without using permanent magnets. Starting from the design of the machine with classical rotor pole that was implemented in FLUX 2D, a finite element analysis software coupled with an optimal design procedure implemented in MATLAB was performed. The purpose of this complex co-simulation was to obtain several outer rotor structures that increase the performances of the machine: saliency ratio, power factor and torque density. For the proposed structures, especially for the modular topology, the obtained results of saliency and power factor have never been presented in the past literature. Hence, this represents a useful starting point for the following analysis of outer rotor synchronous reluctance machines with improved power factor. [ABSTRACT FROM AUTHOR]

A new structure of a linear switched reluctance motor is proposed in this paper. With the permanent magnet inserted in the movers, the performance of the original motor is improved. An electromagnetic analysis is done by using the finite element analysis. The influence of the permanent magnets in different positions of the movers on the electromagnetic force is investigated. Furthermore, a theoretical analysis is made, based on the Schwarz–Christoffel transformation and the Maxwell stress tensor method. The mathematic model is also made with the consideration of the end effect and the cogging effect. The theoretical result of the electromagnetic force is compared with the simulation result. The comparison shows that the error is limited. The analysis of the flux, the magnetic field, and the inductance is then made. The results confirm that the new structure makes the motor more linearized. The new structure of linear switched reluctance motor can contribute to reducing the ripple in the electromagnetic force. [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]

This paper investigates the influence of various Halbach arrays permanent magnets (PMs) on the electromagnetic performance of a radial flux machine with outer rotor topology. The static analysis is performed using a 2-D finite-element analysis (FEA) of six different machines with different Halbach array-based orientations. The gap consideration between PM segments is considered for the first time. The aim of the study is to find the most suitable magnetization topology determination for the PMSMs which brings maximum airgap flux density, coenergy, output torque turning, back-EMF, output electromagnetic power, and minimum corresponding harmonics, cogging torque and the likelihoods of saturation. Additionally, a comparative study of a continuous distribution that commercially is called polar anisotropic will be entirely discussed. The proposed model is verified by FEA, together with its experimental investigation for the small wind power generation application in the urban area. In addition, commercial and environmental issues of the project have been highly considered to reduce CO2 emissions as the part of green power generation mission. [ABSTRACT FROM AUTHOR]

A new modeling of transverse flux linear motor (TFLM) is proposed in this paper. The design consists of three separate stators and one common inner mover. The stators are fed by a three-phase alternating current, and the mover is excited by permanent magnets placed within it. The field distribution of the machine is investigated by using 3D finite element analysis and MagNet® software for electromagnetic simulation. The thrust force characteristics of three-phase TFLM are compared with the single- and two-phase models. It is shown that the average force is increased and the ripple effect of the thrust force is minimized as compared to either single- or two-phase model. [ABSTRACT FROM AUTHOR]

This paper deals with the design, analysis and fabrication of a 320 W, 5 m/s, 4-pole permanent-magnet-based linear synchronous machine (LPMSM). The design deals with conventional hand calculations followed by design fine-tuning and analysis using standard FEM packages. Fabrication of the machine has been also done at the works of a local small machine manufacturer after procurement of imported permanent magnets (PMs). The work presented here focuses on design and fabrication of LPMSM linor stampings with fixed dimensions and standard available PM tablets with a view to providing simple design guidelines. This prototype forms part of a variable speed linear motor drive that is being developed. The approach presented here might provide new ideas to those researchers who may not have the capability to bear cost of fabrication of lamination and PMs from scratch but would like to manufacture LPMSMs from available stampings and tablet PMs. Additionally, it may serve as a base document for the R&D personnel in this area. [ABSTRACT FROM AUTHOR]

Electric bicycles have come to be of public interest due to the awareness of energy preservation and environment. The regulations in many European countries limit the maximum electric motor power to 250 W, which assists the rider up to a bicycle velocity of 25 km/h. Due to the high market competition, electric bicycles are highly cost-sensitive. Currently, most of the electric bicycles use a brushless DC (BLDC) motor due to its compact size and high efficiency. An obvious drawback of a BLDC motor for electric bicycles is the necessity of expensive permanent magnets. Furthermore, the uncertain development of the permanent magnet price also leads to the commercial risk of the product. As a result, the motor concepts without permanent magnets could reduce significant costs and the commercial risk. This paper investigates the feasibility of reluctance motors for replacing BLDC motors in electric bicycles in terms of performances and material costs. The study focuses on two types of reluctance motors, switched reluctance motor and synchronous reluctance motor, which will be compared with a commercial benchmark BLDC motor. The considered reluctance motors will be designed to fulfill the entire torque-speed range of electric bicycles. The motor performances are calculated by design software together with simulation models using the finite element (FE) method. The material cost analysis is done based on the current market prices. [ABSTRACT FROM AUTHOR]

In-wheel direct drive motors are placed inside drive wheels of electric vehicles and have to deliver large torque without any mechanical gear. Most often these machines are of synchronous type with permanent magnets and large pole-pair number. As a consequence of high peak torque, both cogging torque and torque ripple are increased if no measures are taken to decrease them. The vibrations due to cogging torque and torque ripple result in noise and reduced motor durability. In this paper, analytical equations and finite element method are derived, developed and used in order to analyse the dependence of cogging torque on magnet shape and size. A novel magnet shape is found that eliminates cogging torque without reducing the motor torque constant or increasing magnet size. The shape is applicable to any surface mounted permanent magnet motor with high number of pole pairs. [ABSTRACT FROM AUTHOR]

The fast development of the ultra-high speed vertical rotor promotes the study and exploration for the supporting mechanism. It has become the focus of research that how to improve the speed and overcome the vibration when the rotors pass through the low-order critical frequencies. This paper introduces a kind of permanent magnet (PM) supporting mechanism and describes an optimization method of its sensitive parameters, which can make the vertical rotor system reach 80000 r/min smoothly. Firstly we find the sensitive parameters through analyzing the rotor's features in the process of achieving high-speed, then, study these sensitive parameters and summarize the regularities with the method of combining the experiment and the finite element method (FEM), at last, achieve the optimization method of these parameters. That will not only get a stable effect of raising speed and shorten the debugging time greatly, but also promote the extensive application of the PM supporting mechanism in the ultra-high speed vertical rotors. [ABSTRACT FROM AUTHOR]

The paper proposes a novel permanent magnet synchronous machine (NPMSM) with one radial permanent magnet synchronous machine (RPMSM) in the center and two axial permanent magnet synchronous machines (APMSMs) on both sides. The two APMSMs take advantage of the stator end winding spaces of the RPMSM and provide additional output power without increasing the whole machine volume. The emphasis of this study is on the unique rotor structure design and its merits for producing additional output power. The 3D finite element method (FEM), coupling with the equivalent circuit method is used in the study for designing the NPMSM. And the NPMSM prototype test results match well with the calculated results. [ABSTRACT FROM AUTHOR]

This paper presents application of a switched reluctance motor with exterior rotor as an in-wheel direct drive motor for low-power electric vehicles (EVs). A prototype system is realized for experimental studies. Both analytical method and finite-element analysis (FEA) are used in this research to obtain characteristics of the motor. The results of the FEA and analytical calculations are presented, and compared to experimental results. The obtained test and simulation results show that the proposed system is suitable for low-power and low-cost EVs. [ABSTRACT FROM AUTHOR]