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This paper employs an overhang structure for axial flux permanent magnet motor to enhance the torque density. However, the overhang structure requires a computationally expensive 3-D finite-element method (FEM) for analysis, because a quasi-3-D FEM cannot be applied to such a geometry. Thus, in order to reduce the computational cost of above-mentioned topology, this paper adopts a field reconstruction method (FRM). The conventional FRM is applicable only in the case, where the slot pitch to teeth length ratio is the same along radial direction. To address this problem, we introduce a virtual air gap concept so that it can take into account parallel slot effect as well as overhang effect. In this paper, the effectiveness of the proposed method is verified by the 3-D FEM and experimental results. [ABSTRACT FROM AUTHOR]

In this paper, the characteristics analysis of the surface-mounted permanent-magnet synchronous motor is carried out using the method of reflecting the axial leakage magnetic flux into the 2-D finite-element analysis (2-D FEA), and the result is discussed. For the method of projecting the axial leakage flux on the 2-D plane, the permeance coefficient was introduced. By using the proposed method, the parameters such as d- and q-axes inductance and linkage flux for d- and q-axes equivalent circuit analysis were calculated, and the characteristics analysis was performed. In order to verify the effectiveness of the proposed 2-D FEA, a speed versus torque experiment was performed and compared with the analysis results. [ABSTRACT FROM AUTHOR]

In this paper, a changeable winding brushless DC (BLDC) motor for the expansion of the speed region is described. The changeable winding BLDC motor is driven by a large number of phase turns at low speeds and by a reduced number of turns at high speeds. For this reason, the section where the winding changes is very important. Ideally, the time at which the windings are to be converted should be same as the time at which the voltage changes. However, if this timing is not exactly synchronized, a large current is generated in the motor, and the demagnetization of the permanent magnet occurs. In addition, a large torque ripple is produced. In this paper, we describe the demagnetization of the permanent magnet in a fault situation when the windings change, and we suggest a design process to solve this problem. [ABSTRACT FROM AUTHOR]

Recently, dual-rotor motor (DRM) has emerged as an alternative for an induction motor (IM) or a permanent-magnet (PM) motor for electric vehicle application, due to its better drive performance and better torque density. This paper presents an analytical model for the hybrid IM-PM configuration of DRM. The analytical model can be used to predict induced bar currents, electromagnetic torque generated, and magnetic fields in various regions of the motor. The mentioned calculations are performed under steady-state conditions. The analytical method is developed using the subdomain model approach in 2-D polar coordinates. Appropriate governing equations along with boundary conditions across all the sub-domain regions of the DRM are employed to calculate the magnetic vector potential in all the regions. The developed analytical model has been validated with finite-element analysis for various operating conditions, and high accuracy has been achieved for all the results. [ABSTRACT FROM AUTHOR]

This paper investigates the partial irreversible demagnetization characteristics of magnets in flux-switching permanent magnet (FSPM) machines. Two different partial demagnetization mechanisms in the FSPM machines are modeled and demonstrated. The 2-D finite-element analysis (FEA) results for a baseline 10 kW 15 kr/min ferrite FSPM machine verify the validity of the proposed partial demagnetization model. Performance degradation due to demagnetization is evaluated for the baseline machine based on the FEA results. This paper also proposes a novel design to enhance the demagnetization withstand capability. This research reveals the most vulnerable region of the magnet to irreversible demagnetization in the FSPM machines. It also provides a guideline for developing demagnetization withstand capability improvement techniques. [ABSTRACT FROM PUBLISHER]

This paper presents a novel flux-modulated type dual-axis motor that has two mechanical inputs/outputs, since it consists of a stator, a permanent magnet rotor, and a modulating rotor. Furthermore, since the dual-axis motor has a function the same as a planetary type magnetic gear, it can transmit torque with arbitrary gear ratio and divide mechanical input/output into two rotors without any mechanical contact. In this paper, first, conventional and proposed flux-modulated type dual-axis motors are optimized and compared using finite-element analysis. Next, the proposed dual-axis motor is prototyped and demonstrates the validity and availability by experiment. [ABSTRACT FROM AUTHOR]

This paper investigates a double stator linear rotary permanent magnet motor (DSLRPMM) with orthogonally arrayed PMs. The DSLRPMM, which involves linear and/or rotary movements, is constituted of two stators and a hollow mover. The aim of this paper is to study the electromagnetic features and optimize the design parameters of the motor using a 3-D finite-element method (FEM). The topology and the operating principle are described, and the original design is given. The influences of the main designed parameters on the electromagnetic torque, force, and total losses are also analyzed. The optimal parameters are given and a prototype is built and tested. The experimental results are in agreement with that of the 3-D FEM analysis. [ABSTRACT FROM PUBLISHER]

This paper presents the magnetic and electrical equivalent circuits of a hysteresis interior permanent magnet (IPM) motor. A hysteresis IPM motor is a solid rotor hybrid synchronous motor combining hysteresis phenomena and permanent excitation in the rotor. When installed in thousands of feet under the sea to drive an electric submersible pump (ESP), it can self-start the ESP without the need of any position sensors, and can improve the efficiency, the performance, and the reliability of the ESP. In this paper, equivalent circuit models are used to predict the transient run-up responses of a 2.5 kW prototype hysteresis IPM motor. Analysis results are compared with 2-D finite-element analysis (FEA) results as well as experimental results. There exists a reasonably close agreement between analytical, FEA, and experimental results, which validates the accuracy of the equivalent circuit models of a hysteresis IPM motor. [ABSTRACT FROM PUBLISHER]

This paper deals with the modeling and simulation of the effect of rotor eccentricity in permanent magnet synchronous machines. Static eccentricity is analyzed in a 2-D setting. The 3-D effect of an inclined rotor shaft is accounted by considering 2-D slices and interpolating on a grid constructed from finite-element simulations [response surface model (RSM)]. Common tools of uncertainty quantification, i.e., generalized polynomial chaos and Monte Carlo, are used to study the effect on the electromotive force. The novelty of this paper is the twofold use of the RSM: 1) to speed up the calculations in the 2-D setting and 2) to mimic a multislice model for inclined eccentricity. [ABSTRACT FROM AUTHOR]

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

This paper presents a novel analysis and a design method of surface-mounted permanent magnet (SPM) machines with fractional slot concentrated windings (FSCWs) for a given constant power region ratio. The characteristics of working points in the constant power region are analyzed, and a method of quantifying important parameters, magnet flux, and synchronous inductance is proposed. According to the analysis, the design method of SPM machines with the FSCWs and notes is provided. Based on the proposed method, a double-layer 20-pole/24-slot SPM machine is taken as an example and designed. The designed machine is analyzed by the finite element method (FEM), and the constant power experiment is carried out on the prototype manufactured as design. The results validate the analysis and the design method in this paper. [ABSTRACT FROM AUTHOR]

An analytical method for calculating the no-load magnetic field of external rotor permanent magnet brushless direct current motor (PMBLDCM) used as in-wheel motor of electric vehicle in the stator static coordinate and the rotor motion coordinate is presented in this paper. First, the analytic formulas of slotless permanent magnetic field in both coordinate systems are derived, respectively. Then, the complex relative permeance of external rotor PMBLDCM in both coordinate systems is calculated. Finally, the analytical solution of the no-load magnetic field in both coordinate systems is derived by applying the magnetic potential multiplied by the complex relative permeance. In this paper, a 46-pole-51-slot external rotor PMBLDCM is taken as an example, and the accuracy of the proposed analytical model is verified by the finite-element results. Based on the analytical model, the influences of the stator slotting effect on the no-load magnetic field of the external rotor and the inner stator are analyzed. The spatial order characteristics and frequency characteristics of the no-load magnetic field of the external rotor PMBLDCM in both coordinate systems are revealed, respectively. [ABSTRACT FROM AUTHOR]

We have previously been proposed a novel adaptive finite-element method (FEM) based on a magnetic field conservation indicator and a non-conforming mesh-refinement technique. However, we have applied to a very simple model consisting of a single permanent magnet for basic verification of the proposed method. In this paper, we have improved an error indicator, and tried to apply a newly proposed adaptive FEM to more complicated models, where ferromagnetic material is included. The newly proposed method is superior in torque error estimation to the Zienkiewicz-Zhu error estimation method in a 3-D permanent magnet motor model. [ABSTRACT FROM AUTHOR]

In this paper, a new hybrid permanent magnet (PM) synchronous motor with two-part rotor is proposed. The new motor is composed of surface mounted and interior magnet rotor segments on a stepped skewed shaft. The hybrid topology has wider constant power speed ratio than conventional surface mounted PM motors with relatively the same torque density. No-load and on-load finite-element analyses (FEA) are performed independently for both surface PM and interior PM synchronous motor. Superposition of the results is gathered to obtain the actual performance of the hybrid motor. The 2-D FEA results with skewed models are also performed at the final stage of the design. A prototype motor is manufactured and experimental results are obtained. Good agreement is observed between the simulations and test data for the proposed motor. [ABSTRACT FROM AUTHOR]

This paper aims to analyze the characteristics of a surface permanent-magnet Vernier motor (SPMVM) according to the pole ratio among the rotor magnet pole pairs, stator teeth, and winding pole number. The SPMVM has the same operational principle as a magnetic gear, and it is operated using the space harmonics of the air-gap flux density due to the magnetomotive force and air-gap permeance. In this paper, first, the design parameters of the SPMVM are specified based on an analytical calculation of the air-gap magnetic flux density. Moreover, various combinations of the rotor magnet pole pairs and stator teeth number are made and compared according to the operational principle of a Vernier motor using a 2-D finite-element method. [ABSTRACT FROM AUTHOR]

This paper analyzes the characteristics of a vector-controlled permanent-magnet synchronous motor (PMSM) with a permanent-magnet defect. A method for the diagnosis of the demagnetization of the permanent magnet in PMSM is proposed. In the proposed method, the magnetic field is calculated by the finite-element method, and then the flux linkage and d and q axis inductances are calculated. They are introduced into the block diagram of the drive and control system. We have manufactured interior permanent-magnet motors, where one of four magnets is reduced by 10% and 20% in order to imitate the demagnetization. It is shown that the Fourier and wavelet results are in good agreement with the measured ones. This paper shows that the stator current and stator voltage using the proposed method are useful for the fault detection of demagnetized permanent magnet. [ABSTRACT FROM PUBLISHER]

Spoke-type interior permanent magnet (IPM) machines are an attractive topology for high-performance electric motors, especially designed for vehicle traction applications. In this paper, a special design for a spoke-type IPM motor is presented to enhance motor flux-weakening capability in the operation over a wide speed range. The proposed design consists of a simple and robust mechanical device that includes radially displaceable rotor yokes, connected to the shaft by means of springs. At high speed, the centrifugal force prevails over the elastic one due to springs, causing the mobile yokes to displace radially and establish a partial magnetic short circuit between PMs. This increases PM leakage flux and consequently reduces the air-gap field. As a result, a mechanical flux weakening effect is achieved at high speed, which helps significantly to reduce the demagnetizing \boldsymbol d -axis current to be injected by the inverter, along with the related copper losses and demagnetization issues. The proposed design is investigated in this paper using an analytical model whose parameters are computed by finite-element analysis. The effectiveness of the solution being set forth is successfully proven by some testing on a laboratory prototype. Experimental results are compared with analytical predictions showing a satisfactory accordance. [ABSTRACT FROM AUTHOR]

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

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

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

This paper introduces a novel hybrid-excited stator slot opening permanent magnet (PM) machine (HSSPMM). The operation principle of the machine is described and the effects of rotor eccentricity and magnetic saturation due to PMs on electromagnetic performance, with particular emphasis on back electromotive force (EMF), are analyzed by finite element method (FEM). It shows that different from the conventional PM machines, the open-circuit back EMF in this novel HSSPMM should be zero but may become non-zero if significant magnetic saturation exists, and furthermore, the rotor eccentricity has a detrimental effect on the waveforms, amplitudes, and symmetries of three-phase back EMFs, as confirmed by FEM and tests. [ABSTRACT FROM AUTHOR]

This paper presents an effective method for calculating the current excitations for optimal operating condition of interior permanent magnet (IPM) synchronous machines for traction application. The relationships between torque, current amplitude, and current angle during optimal operation are studied. For a given torque and speed command, the steps of searching for the ideal current excitations can be simplified using a script developed in ANSYS Maxwell, which significantly accelerates the process of evaluating performance and creating efficiency map of an IPM machine. [ABSTRACT FROM AUTHOR]

In this paper, each component of the no-load loss of interior permanent magnet motors under the conditions of both sinusoidal supply and converter supply is investigated by the finite-element method and experimental method. The no-load loss is calculated at different rotation speeds, two different slot and pole combinations and different converter parameters. The wireless temperature sensor embedded in the interior rotor is used to test the temperature of the permanent magnet under no-load condition, and the permanent magnet loss is calculated according to the slope of the initial temperature–time curve. Then, the mechanical loss of the prototype is measured by dragging a nonmagnetic rotor. The total tested losses are subtracted from the copper loss, the mechanical loss, and the permanent magnet loss to obtain the test results of core loss, and the experimental results of each loss and permanent magnet temperature rise are compared with the corresponding calculated results to verify the correctness of the simulation results. [ABSTRACT FROM AUTHOR]

In this paper, a planar flux-switching permanent magnet (PFSPM) motor, which is the first of its kind for planar motors, is designed and analyzed. First, the topology structure, modeling, and operating principle of the PFSPM motor are clarified. Then, the initial dimension of the PFSPM motor is determined in terms of its topology structure. Based on the initial dimension, the width of the iron core and the length of the permanent magnet are optimized to increase the thrust force and reduce the cogging force. In addition, a 3-D finite-element analysis (FEA) is performed. Finally, the experiments are conducted based on a developed prototype of the PFSPM motor with the optimized dimension. The results demonstrate that the thrust force is increased by 21%, and the cogging force is reduced by 56% via FEA; the thrust force of the experimental measurement is largely consistent with that determined via the FEA. [ABSTRACT FROM AUTHOR]

This paper presents the design of cryogenic permanent magnet synchronous motor (C-PMSM) for submerged liquefied natural gas (LNG) pump. The motor is submerged in LNG with a cryogenic temperature (CT) of −161 °C, and its magnetic and electric characteristics differ greatly from that of the motor at room temperature (RT). So it is necessary to redesign according to the result of conventional design, considering the changes of materials under the cryogenic environment. The operating characteristics of the C-PMSM are investigated, and the redesign method is discussed. Finite-element method is used to analyze the motor performance. A prototype is fabricated and tested to verify the rationality of the design. [ABSTRACT FROM AUTHOR]

This paper presents the study of an entirely electromagnetic traction system to be used for electric vehicle (EV) application. To have a reduced mass and compact system, the electric motor will work at 40500 r/min. Usually, the high-speed electrical machines are rather used for ventilation or compressor systems, with low dynamics. The high variation of the load torque in EV application demands the best possible mechanical/energetic performances. The traction system proposed here is composed by a high-speed permanent magnet motor linked to a magnetic gear. This paper will present the technology of the entirely electromagnetic traction chain and its energetic and mechanical performances. The results are validated numerically through finite-element analysis. [ABSTRACT FROM AUTHOR]

Although three-phase permanent magnet (PM) motors are dominant in industry, multi-phase PM synchronous motors present higher torque-to-weight ratios, better efficiency, and low torque ripple compared with three-phase conventional PM motors. These features make fault-tolerant multi-phase PM motors become attractive for safety-critical applications. In this paper, a novel PM multi-phase motor design with a dual three-phase asymmetric stator winding is proposed. The winding structure of the proposed motor is unconventional due to selected slot–pole combinations. Therefore, an asymmetric winding is needed. The detailed finite-element analysis of the proposed motor and a performance comparison between the conventional integer-slot (72-slot/12-pole motor) with symmetric winding and the unconventional fractional-slot (78-slot/12-pole motor) PM motors with asymmetric windings is performed to see the benefits of the proposed motor. It was shown that the novel unconventional multi-phase PM motor has excellent torque quality and slightly higher torque density levels. [ABSTRACT FROM PUBLISHER]

The aim of this paper is, first, to extend the application of the hybrid analytical modeling (HAM) approach for the analysis of tubular linear machines (TLPM), something that has never been reported yet in the scientific literature. The HAM consists of a strong coupling between the reluctance network and the Fourier series solution of magnetic scalar potential. In order to assess the merits and capabilities of the HAM, it is applied to the study of the cogging force in linear machines and compared with finite element analyses (FEA). The cogging force is a global quantity, which is very sensitive to magnetic field computation accuracy and constitutes, therefore, a good measure of the accuracy of the HAM as compared with FEA. The HAM should require less computation time as compared with FEA, and is then more suitable for predesign stage. Three different structures are analyzed: a flat linear machine, a TLPM with internal mobile armature, and, finally, a TLPM with external mobile armature. The analyses are conducted, considering the effect of magnetic saturation. [ABSTRACT FROM PUBLISHER]

This paper presents an exact analytical subdomain model of slotted permanent-magnet (PM) machines, taking into account the diffusion effect. The model gives the magnetic fields, both the eddy currents and the power losses in the PM, the instantaneous and average torque. In the model, eddy currents are not assumed to be resistance limited, contrary to what is done in the conventional exact subdomain models of the slotted machines. The model is hence general and valid both at low and high frequencies. It shows that it is possible to calculate the power losses in the PMs, only knowing the fields in the air gap. The model takes into account the presence of tooth-tips. The comparison with conventional exact subdomain models shows that the model presented in this paper is more accurate. The model is validated using the finite-element methods. [ABSTRACT FROM AUTHOR]

Helical windings (or zigzag windings) are used in a number of applications, however, in electrical machines, mainly employed in low-power, high-speed permanent magnet (PM) brushless dc machines due to the cost effectiveness of the winding type while maintaining reasonable performance. Typically, helical windings are used for low-voltage applications due to their spiral form, which makes them most suitable for a small number of turns. In high-speed electrical machines, such a low number of turns are applicable. It is apparent that high-speed PM machines suffer from rotor eddy-current losses, which in some cases may lead to PM demagnetization due to overheating. The performance of the machine is compromised by these losses; hence, they have to be considered during the design procedure. There are many papers analyzing the magnetic field of these machines employing helical windings; however, none of them present a simple and precise electromagnetic model of a machine with the helical winding. This paper presents an analytical approach to model the resulting 3-D magnetic field of the helical winding, considering eddy currents in the conducting media of the rotor. The model is verified with the 3-D finite-element method by means of comparing magnetic field and rotor eddy-current losses. [ABSTRACT FROM AUTHOR]

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

Interior permanent magnet (PM) synchronous motors are widely used in electric vehicle, where limited space for motors is one of the most crucial challenges. This paper proposes an analytical design method to decrease iron losses, which saves much computation time compared with the parameter sweep method adopting finite-element analysis (FEA). The new method provides a design principle of the rotor, by which the harmonic magnetomotive force of the PM and the iron losses can be reduced significantly. This paper also takes the influence of the pole arc angle on iron loss reduction into consideration. The validity of the analytical technique is verified by 2-D FEA. [ABSTRACT FROM AUTHOR]

High-speed permanent magnet machines, supplied by pulsewidth modulation (PWM) voltage source inverters, operate with distorted stator currents. Harmonics present in these stator currents deteriorate the machine performance by generating losses. Mostly, these losses are following the machine design using a transient finite-element model. The precise measurement of these rotor eddy-current losses is extremely difficult, hence, only a few papers provide convincing comparisons between predictions and measurements. This paper presents a fast and precise analytical approach, verified with measurements, to consider rotor losses of machines, supplied by PWM voltages, already during the design procedure. [ABSTRACT FROM AUTHOR]

This paper proposes the maximum thrust design of slotted permanent magnet linear synchronous motor (PMLSM) using equivalent magnetizing current method (EMCM) considering slot effect. The genetic algorithm is used for optimization. The objective functions are selected for the maximum thrust and the minimum detent force. In this paper, design parameters are set as permanent magnet (PM) width, PM height, and slot width. Thrust is increased from 272[N] to 295[N] and detent force is decreased from 5[N] to 2.43[N] greatly in optimum design. Therefore, most thrust ripple has not been generated. Also, the results of 2D EMCM considering slot effect are compared with ones of experimental and finite element analysis. [ABSTRACT FROM AUTHOR]

Considering the basic role of the stator magnetic field (MF), this paper presents a synthesis strategy for stator MF of a permanent magnet spherical motor (PMSM). Given the structure of the PMSM, the MF of a stator coil group with unit current is obtained, and the spherical harmonic components are decomposed, so the relationship between the whole stator MF and coils currents can be deduced by the rotary transformation and superposition. Referring to the rotor MF, the expected stator MF is determined; then, the stator coil currents are calculated by solving a constrained optimization. Finally, the current excitation strategy of stator coils is verified by finite-element analysis and experiments. [ABSTRACT FROM AUTHOR]

This paper investigates a novel miniature-size resonant moving-magnet linear actuator designs to be used in miniature linear compressor applications. The miniature linear actuator has a slotless stator and a tubular topology. It utilizes moving magnets in which the magnets are lined up in the Halbach array structure. Finite-element and analytical analyses of the actuator are performed to determine the flux density and thrust force. Experimental thrust force behavior at the resonant frequency is determined. It is shown that the finite-element method simulation, analytical, and experimental results agree with each other. [ABSTRACT FROM AUTHOR]

This paper examines the maximum cogging torque (MCT) distribution characteristic of surface-mounted permanent-magnet (SMPM) machines. The MCT distributions of SMPM machines with different pole-arc coefficients and different ratios of slot opening to slot pitch are studied using: 1) the Fourier series analysis together with the Maxwell stress tensor and 2) the finite-element method. Right triangle distribution regions of the optimal MCT are determined by comparing the MCT distribution contour maps obtained by the afore-mentioned two methods. Finally, a combined MCT optimization method for an SMPM with substantial savings in the optimization time, when compared with conventional methods, is proposed. [ABSTRACT FROM AUTHOR]

In our previous study, the claw pole motor (CPM) shows promising magnetic concentrating performance for permanent magnet motors with soft magnetic composite cores. Meanwhile, its relatively complex structure also increases the core loss and cogging torque. To conduct the high dimensional optimization of the CPM with comprehensive analysis models, this paper presents an improved multilevel strategy of high efficiency. Since the holistic performances, including output torque, efficiency, cogging torque, and back electromotive force, are considered, an orthogonal design is utilized for the surrogate model building for increasing the optimization efficiency. A full factor sample method for the surrogate model is also conducted for comparison. The similar optimization results with the two kinds of models prove the effectiveness of the proposed method and optimal design. [ABSTRACT FROM AUTHOR]

The effects of temperature-dependent material properties, including those of silicon steel and permanent magnet (PM) materials, on the design process of inverter-fed PM motors are investigated in this paper. The magnetization curves of these materials are measured experimentally at different temperatures and are imported into a finite-element package. Then, a statistical study of an integrated motor-drive system consisting of an interior PM motor connected to a space vector modulated inverter is performed by assigning four different temperatures and building a design space of various objectives including the integrated system efficiency, speed limits, motor startup quality, torque ripple, total harmonic distortion, and power factor as the geometrical dimensions are varied. The results reveal that incorporating the realistic material properties into the design process is essential. Moreover, different motor-drive performances have totally different variation rates as the material properties are changed. Finally, a set of optimal designs at different temperatures is proposed to show the effect of changing material properties. [ABSTRACT FROM AUTHOR]

Large amounts of harmonics are contained in the current as the motor is driven by pulse width modulation (PWM). Significant amounts of computing time are required to compute local flux density variation considering such current harmonics. Since the amplitudes of higher harmonics are significantly smaller than that of fundamental harmonic, flux density variations due to the higher harmonics are small, and the relationship between the field strength and flux density can be assumed to be linear. When the operating point of each element is known, flux density variations for the higher harmonics can be analyzed by linear finite-element analysis (FEA). This paper suggests a method to calculate flux density variations in the iron core while taking into considering PWM current harmonics. First, the operating point solution is obtained by nonlinear FEA, second each element is linearized. Then, the flux density for the PWM current is obtained through linear FEA. Finally, the obtained results are presented and compared with nonlinear FEA results for verification. [ABSTRACT FROM AUTHOR]

This paper presents a new axial flux permanent magnet machine, named ring winding axial flux machine (AFM). The ring winding AFM (RWAFM) takes the advantage of segmented stator of yokeless and segmented armature topology with those of decoupled phases and ring winding of transverse flux topology. In this paper, the geometry of the RWAFM is introduced in detail. Furthermore, the working principle and torque production theory are discussed. To validate the concept and confirm manufacturability of the proposed topology, a prototype is fabricated. The performance of the RWAFM is studied through experimental tests, 3-D finite-element simulations, and analytical discussions. [ABSTRACT FROM PUBLISHER]

The radiated electromagnetic interference (EMI) behavior may have a negative impact on the machining accuracy of grinding machines. Therefore, this paper focuses on the radiated EMI generated by an ultra-precision pulsewidth modulation permanent-magnet synchronous motor (PMSM) drive system. The excitation for the radiated EMI model, the common-mode (CM) ground current at the output terminal of the converter, is obtained by simulating its conducted EMI model. The reasonable simplified FE models for the converter frame, the shielded power cable, and the motor frame are established. In addition, an equivalent circuit macro model of the CM impedance of the three-phase PMSM windings is obtained by using impedance measurements, the vector fitting method, and the fast residue perturbation method. Finally, the 3-D time harmonic field-circuit coupled finite-element method is employed to evaluate the radiated EMI. [ABSTRACT FROM AUTHOR]

In this paper, a new topology of a single-phase flux switching permanent magnet motor (FSPM) is presented. Unlike conventional FSPMs, the air-gap flux flows in the axial direction, and therefore, it is named the flux switching axial flux permanent magnet motor (FS AFPM). The proposed single-phase FS AFPM has a compact disc-type structure, four stator pole teeth, and two rotor pole teeth (4/2 combination). However, a number of the stator poles as well as the rotor poles can be easily increased, due to an enlarged circumferential length. It has two discs, one for the stator and other for the rotor. Like conventional FSPMs, this machine has a simple salient rotor pole structure. Along with the armature windings, the PMs are also embedded in the stator. A 3-D finite-element analysis is carried out for the characteristic analysis of the proposed single-phase FS AFPM. For the enhancement of the self-starting torque capability and unidirectional rotation, the rotor pole is tapered. [ABSTRACT FROM AUTHOR]

Linear magnetic-field modulated (LMFM) motor exhibits high thrust force by effectively employing the magnetic-field modulation effect. In this paper, a new mover separated LMFM (MS-LMFM) motor is proposed, which successfully alleviates the space confliction between permanent magnets (PMs) and windings in the existing LMFM motor. The structure and the operation principle of the existing and proposed motor are described, and the major design parameters are optimized for maximum thrust force. Moreover, electromagnetic performances of both motors are compared by finite-element method. Theoretical and simulation analysis shows that the proposed motor can exhibit enhanced force performance than the existing one under fixed copper loss. Simultaneously, reduced iron and PM losses can also be obtained by proposed motor. Finally, a 3-D modeling MS-LMFM motor is built for a global observation of motor structure and further verification of the 2-D analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a dual notched design of radial-flux permanent magnet (PM) motors with gear-shaped structures on the PM and stator teeth aiming at lowering down cogging torque and rear earth material (REM). Due to the restriction on export quotas of REM, its cost is expected to rise drastically in the near future. The low cogging torque and REM in PM motor design, therefore, are of high significance. This paper presents a design taking a big step toward that direction. Four models with different mechanical angles and depths were designed. With the aid of 3-D finite element analysis and simulation, the one that best matched objectives was selected which resulted in percentage reduction of the cogging torque and REM up to 62.8% and 6.7%, respectively. In the transient simulation, the output torque of a dual notched PM motor compared with a normal structured one was reduced to 6.5% in average. A prototype was also fabricated to validate the design. [ABSTRACT FROM AUTHOR]

Although demand for the multi-segmented and multi-layered (MSML) interior permanent magnet (IPM) motor is high, the analytic method for this motor has not yet been proposed. The finite element method has been used in the analysis and design of the MSML IPM motor, even though it takes much time to perform. To solve this problem, the correct and rapid analytic analysis method for the MSML IPM motor is proposed in this paper. This method is called the MCC method because it is the combination of the Magnetic equivalent circuit, Conformal mapping to consider slotting effect, and Concentration flux of IPM. Furthermore, the feasibility of the optimization of the MSML motor by using the proposed MCC method is verified in this paper. [ABSTRACT FROM AUTHOR]

This paper presents a novel double salient motor design in which the permanent magnets are implanted in the stator to provide additional magnetic flux sources for enhancing its performance and reducing the inherent cogging torque. The feasible cones method is adopted to calculate the dimensional sizes of the proposed short flux path motor. The assembled stators concept is employed to design the magnetic flux paths of the double salient permanent magnet (DSPM) motor and also transfer the heat generated by the windings outside the motor. Due to the nonlinear properties of the doubly salient structure, this paper utilizes both magnetic circuit analysis and finite element analysis to evaluate different operating characteristics of the designed DSPM motor. Experimental data are provided to verify the proposed design. [ABSTRACT FROM AUTHOR]

Three-dimensional (3-D) finite element analysis is generally required to analyze the performance of an axial flux permanent magnet (AFPM) motor because it has asymmetrical characteristics along the z-axis. Although the computing performance of CPU is enhanced owing to technological developement, a large amount of analysis time is required for 3-D finite element analysis (FEA). This paper presents a method of AFPM motor to an equivariant linear synchronous permanent magnet (ELSPM) motor, both of which have identical output performance. The output performance of the proposed ELSPM motor becomes identical to that of the AFPM under the mandatory condition that the PM magnetic energy of both the models must be identical. The validity of the proposed ELSPM motor in terms of the accuracy and computation time is verified by comparing its results with the results of the AFPM motor based on the FEA. [ABSTRACT FROM AUTHOR]

Recently, interior permanent magnet synchronous motor (IPMSM) is paying attention because of its high power density and efficiency by adopting permanent magnet. The IPMSM has two control methods: maximum torque per ampere (MTPA) control and flux weakening control. Generally, an MTPA control is applied to a continuous operating point, and in case of a startup point, input current is applied which satisfies required output torque. To control the IPMSM, the various types of inverters with current and voltage limitations are used. The motor cannot be operated if these limitations are not satisfied. This paper proposes a method to satisfy the current and voltage limitations of the inverter with two different operating points. By changing the control method of the rated operating point by a stack compensation method, the current and voltage limitations of the inverter can be satisfied at a startup operating point, where the input current in MTPA control at the continuous operating point cannot be satisfied. The proposed method is verified by a 2-D finite element analysis. [ABSTRACT FROM AUTHOR]

In this paper, dynamic reluctance mesh model (DRM) combined with an improved iron losses prediction model are presented to provide fast and accurate way to evaluate the iron losses for permanent magnet (PM) motors with pulsewidth-modulated power supply. A DRM model for high-speed train PM traction motor is first built. The magnetic field distribution for one cycle is then obtained using the DRM method. An improved engineering model of iron losses prediction is applied. Finally, the simulation and testing results are presented to confirm that the proposed combined method is accurate and effective as the finite element method (FEM) model with much less time consumed. [ABSTRACT FROM AUTHOR]