Search

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]

A novel hybrid-flux permanent-magnet (PM) generator, which has both axial flux and radial flux, is proposed. An axial-flux PM generator is designed by a reluctance network method and the 3-D finite element method. Using these results, this paper proposes a radial-flux and hybrid-flux machine, whose main dimensions are chosen to the same values as a commercialized one. The proposed hybrid-flux machine has the largest output power per volume. The power density of the proposed generator is 9.4 times larger than that of the commercialized one. The efficiencies of the proposed hybrid generator and a radial generator are same as each other, and are larger than those of an axial and the commercialized generators. [ABSTRACT FROM AUTHOR]

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

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]

In this paper, on the basis of a conventional 12-stator-coils/17-rotor-teeth (12/17) flux-switching permanent magnet (PM) (FSPM) machine and a 6/17 V-shaped FSPM machine, a novel 6/17 multi-tooth FSPM machine with a pair of magnets located in the upper apex of stator tooth is proposed. Then, four multi-tooth topologies sharing the same 6-stator-coils but with different rotor teeth combinations, namely, 6/17, 6/10, 6/11, and 6/13, are compared by the 2-D finite element analysis (2-D-FEA). The FEA-predicted results reveal the optimal combinations of stator coils and rotor teeth should be 6/17 for high-performance multi-tooth machines. Thereafter, an optimal design criterion of multi-tooth FSPM machines for the combinations of stator coils and rotor teeth is proposed. Afterward, electromagnetic performance evaluation between the 6/17 V-shaped and 6/17 multi-tooth machines is conducted, in terms of back electromotive force (back EMF), electromagnetic torque, cogging torque, phase inductance, unbalanced magnetic force (UMF), torque/magnet ratio, and efficiency. The comparative results indicate that the proposed 6/17 multi-tooth machine is superior to the V-shaped one, since it exhibits much higher torque/magnet ratio, larger torque, lower inductance, and much lower UMF, though the cogging torque and total harmonic distribution of phase back EMF are unfavorably larger. [ABSTRACT FROM AUTHOR]

Incipient stator winding fault in permanent magnet synchronous wind generators (PMSWGs) is very difficult to be detected as the fault generated variations in terminal electrical parameters are very weak and chaotic. This paper simulates the incipient stator winding faults at different degree of insulation degradation of one turn in the winding of a PMSWG. Cosimulation method by combining finite element model and external circuits is used. Hilbert–Huang transformation is applied to detect the very early stage fault in interturn insulation by analyzing the stator current. Detection results show that the minimum detectable severity degree of interturn fault in this paper is 0.1488%, which is much better than the best record in the literature. [ABSTRACT FROM AUTHOR]

This paper proposes a novel hybrid excitation vernier permanent magnet machine (HE-VPM). The characteristics of the proposed machine are: 1) the PMs are embedded in the stator teeth, which is helpful for the heat dissipation; 2) the rotor is salient structure without PMs and windings, which ensures the reliability of high-speed operation; 3) the nonoverlapping concentrated winding shortens the end-connection, and improves the torque density, 4) only half of the stator teeth possess PMs, and the total amount of PMs are decreased; and 5) the dc current are injected to the armature coils, therefore, the exciting field can be adjusted flexibly. In this paper, the electromagnetic performance, including back electromotive force, torque, etc. are analyzed with finite element analysis. The results show that the proposed machine exhibits flexible field adjustment capability, which may be suitable for applications requiring wide speed range operation. Besides, it is found that, compared with the existing pure sinusoidal phase current, higher torque density can be obtained with dc-biased phase current under constant stator copper loss. [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 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 develops an approach that is capable of accurately predicting the performance of synchronous reluctance motors (SynRMs). The SynRMs receive increasing attention and have been used in many industrial applications. The 2-D finite element analysis (FEA) is usually considered to be competent for design and analysis of SynRMs. However, the power factor of SynRMs is likely to be considerably overestimated. This would then lead to an underestimation of current required and cause problems for the design of electronic drivers. Compensation should be made to improve the accuracy of the analysis for SynRMs although there does not seem to be a solution put forward so far. The research in this paper shows that the exclusion of end turn leakage inductances in 2-D analysis is a key factor to cause such a significant difference. To resolve this problem, this paper analytically calculates the end turn leakage inductance, which is then incorporated into the 2-D FEA. The developed method is found to agree well with the experimental results, and it significantly improves the design accuracy and efficiency using only the 2-D FEA. [ABSTRACT FROM AUTHOR]

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

This paper 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]

From a new stator-flux perspective, a comparative study between the series and parallel hybrid excitation machine (PHEM) is conducted and it is revealed that in PHEMs there still exist distinct stator-flux harmonic components during high-speed flux weakening operation, which could be further utilized to improve the torque capability at high-speed range. Inspired by this idea, an auxiliary winding is creatively introduced into PHEMs to recycle and utilize the magnetic field energy generated during the field regulation. A new design case is presented in this paper, in which two sets of armature windings with different pole pair numbers are arranged to realize the function of flux weakening operation and energy recycling, respectively. The feasibility of this new hybrid solution is evaluated by using the finite-element analysis. Furthermore, a prototype is manufactured and relevant experiments are performed. The experimental results agree well with the theoretical analysis and simulation results, which verify that the recycled energy can be effectively used to boost the output torque and power of PHEMs in the high-speed region. [ABSTRACT FROM AUTHOR]

An electrical motor’s inverse thermal model formulates the precision with which its power losses can be predicted from noisy local temperature measurements. This paper proposes constrained linear least square optimization followed by noise smoothing as a method to accurately predict a 37 kW induction motor’s power loss components. The anisotropic heat transfer and complex geometry of the motor are represented well by the motor’s lumped thermal network and 3-D finite element models, which characterize its intrinsic heat-transfer processes. With the inverse solution method, satisfactory temperature to power inverse mapping was achieved for different sets of noisy temperature inputs simulated from analytical and numerical forward solutions. This paper demonstrates that even with measurement noise in input data, if reliable information about the expected response of the system is available, an accurate reconstruction of power losses can be achieved. [ABSTRACT FROM AUTHOR]

The brushless doubly fed induction machine (DFIM) is a special machine type that is of interest as a generator in wind turbine drive trains. The brushless DFIM has a significant space-harmonic content compared with conventional machine types, due to its construction. This results in additional harmonic distortions, such as torque-ripple and time harmonics. This paper studies the causes and origins of harmonic distortions in the brushless DFIM. Using time- and space-harmonic analysis, an analytical evaluation method is derived to predict the torque ripple frequencies and time-harmonic frequencies in stator and rotor voltages and currents. The evaluation method is applied to a prototype brushless DFIM to demonstrate the severity of harmonic related distortions that can be present in the brushless DFIMs. The evaluation is validated by additional finite-element analysis and measurements. Furthermore, measures are proposed to reduce harmonic distortions. The insight into harmonic distortions in the brushless DFIM and the ability to predict and prevent them must lead to the improved brushless DFIM designs in the future. [ABSTRACT FROM PUBLISHER]

Analytic modeling techniques of a double-sided interior permanent-magnet flat linear brushless motor (IPM-FLBM) with slot-phase shift and alternate teeth windings are proposed in this paper. Since the buried-type IPM-FLBM with the slot-phase shift and alternate teeth windings is fairly new compared with conventional linear motors, little research has been previously done in modeling and analysis. The analytic models presented in this paper provide the effective and reliable methods for this new type of linear motor. For this purpose, a simplified magnetic equivalent circuit and superposed winding function are investigated. A variable winding function is newly developed in order to evaluate the inductances of the salient motor with the alternate teeth windings. All analytic models are verified with 3-D finite-element analyses (FEAs) step by step. The steady-state thrust force is modeled using a classical closed-form solution for linear brushless ac motors. The static end-effect and cogging forces for the ripple force evaluation are investigated using FEA. The validities for performance parameters are demonstrated experimentally. [ABSTRACT FROM PUBLISHER]

Electric continuously variable transmission (e-CVT) device is a key component in hybrid electric vehicles (HEVs), which serves to perform the energy transmission among the initial combustion engine, battery, and output shaft. This paper presents a novel consequent-pole PM magnetic-geared double-rotor machine (CPDRM) that utilizes the magnetic gearing effect to transmit the power with a high efficiency. The artistry of CPDRM is to insert a dc winding within the center of the stator on the circumferential direction. Therefore, the machine can extend the constant-power region by changing the current direction and amplitude of dc windings. Meanwhile, the flux density within the air gap is changed accordingly. Then, the working principle of CPDRM and the flux change process are illustrated by employing the magnetic circuit method. Finally, a finite-element method model is constructed to verify the performances of the CPDRM under different operating modes. The result shows that the proposed machine has an excellent flux-weakening ability, and it can serve as a suitable candidate as an e-CVT component for HEVs. [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]

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

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 a novel consequent-pole hybrid brushless wound-rotor synchronous machine (CPH-BL-WRSM). The proposed machine employs permanent magnets (PMs) on the alternate poles of the salient pole rotor, which has considerably less magnet usage compared to the regular (PM) assisted synchronous machine. The proposed CPH-BL-WRSM offered the advantages of high starting torque, high torque density, and better performance under full-load conditions. The BL operation for the proposed machine is achieved by generating a composite magneto motive force (MMF) with a fundamental component and sub-harmonic component. The sub-harmonic component of the stator MMF is used for BL excitation of the rotor. The finite-element method was used to analyze the performance of the CPH-BL-WRSM in comparison with the performance of the existing BL-WRSM and regular PM-assisted BL-WRSM. Finally, a prototype of the CPH-BL-WRSM was manufactured and the experiment was conducted to demonstrate the performance of the proposed CPH-BL-WRSM. [ABSTRACT FROM AUTHOR]

Slotless permanent magnet machines are attractive in some modern drive and power generation fields, where the cogging torque and additional losses need to be minimized or removed. The stator slotless design can be combined with different surface permanent magnet (SPM) rotor topologies. In this paper, explicit analytical expressions are derived to analytically compute the slotless machine torque and no-load back Electro-Motive Force in the case of segmented SPM rotor with parallel, radial, or Halbach-array magnetization patterns. The expressions are found by solving the magnetic field due to the slotless stator winding and to the permanent magnet blocks; the latter modeled through equivalent surface current densities. The accuracy of the method is successfully assessed by comparison with the finite-element analysis (FEA). The proposed formulas are an effective alternative to the FEA to quickly compare different design solutions as well as to optimize them. Application examples are provided in which the presented method is adopted to define the machine cross section that maximizes the torque density. [ABSTRACT FROM PUBLISHER]

This paper presents the analysis of a brushless doubly fed reluctance machine (BDFRM) for renewable energy applications with an emphasis on the rotor design. The BDFRM stator includes two sets of windings, i.e., the control winding (CW) and power winding (PW). The PW is connected to the grid, while the CW links the grid by a power converter of fractional rating to regulate the operating speed. This reduces the converter cost, and the brushless configuration enhances the reliability. In this paper, the reluctance rotor of the BDFRM, which is similar to that of a synchronous reluctance machine, is designed and analyzed in order to improve the performance. The influence of the total MMF and its allocation to the two stator windings are also discussed in relation to the machine performance. Finite-element analysis is used for performance simulation. The experimental study validates the proposed design for a small BDFRM. [ABSTRACT FROM PUBLISHER]

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]

This paper presents a fast method to compute wound rotor induction machines in steady state. Coupled time-harmonic finite-element (FE) circuit equation is used under a first space harmonic approximation for the air-gap magnetic field. It is shown that only four magnetostatic FE computations are necessary to determine the machine performances for any slip value. The performance comparison with a conventional complex magnetodynamic and time-stepping FE analyses show the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper presents the design of a new flux switching device that is capable of coupling with surface permanent magnet motors to become a new actuator featured with autolocking, increased safety, and higher energy utilization. These advantages are based on the concept of flux switching and the alternation of electric power with cogging torque. In this design, four additional axial winding coils are proposed to smoothing the switching process and provide bidirectional rotation. In addition, different manufacturing processes of the inner rotor are discussed with the aim of simplifying the fabrication process. The torque characteristics are investigated experimentally and analytically using a prototype and a finite-element analysis tool, respectively. [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]

In this paper, a new shaded-pole main exciter (ME) with additional short-circuited coils for aircraft three-stage starter–generator (SG) is proposed and investigated. The basic structure, winding configurations, operating principle, and start system structure of the presented shaded-pole ME are illustrated in detail. The comparative study between the original ME and the shaded-pole ME with respect to the starting mode performances is conducted by 2-D finite-element method (FEM). A prototype SG with original ME has been developed, and the experimental results are essentially consistent with the simulation results by the FEM utilized in the predictions in this paper. Simulation data and waveforms verify that the proposed shaded-pole ME is a good candidate for aircraft machines to satisfy the dual function of starter and generator. [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]

A partitioned stator-flux reversal (FR) permanent magnet machine (PS-FRPMM) is a new combination of a stator PM machine and a magnetically geared machine and has the specifications of both machines in terms of robust structure and torque density. In this paper, a comprehensive 2-D analytical model is developed for PS-FRPMM based on subdomain technique. The presented model has the capability to accurately and quickly investigate the effects of design parameters on the machine performance. The 2-D analytical model is evaluated on two case studies with 12 stator teeth and 10 rotor poles, and 18 stator teeth and 13 rotor poles, with four different magnetization patterns. The influences of various design parameters such as the rotor slot width, slot opening width, and the segment ratio of the PMs in the two-segment magnetization pattern have been investigated on the quantities, such as the instantaneous torque, torque ripple, unbalanced magnetic force (UMF), and electromotive force (EMF). For evaluating the presented analytical model, the 2-D finite element method (FEM) with and without saturation effects has been used. The comparative study between the analytical and numerical models shows good agreement. Finally, a 3-D FEM has been used, and the results of the 2-D analytical model and 3-D FEM are compared in terms of the accuracy and computational time. The results show that the presented model has lower computational time compared to the 2-D and 3-D FEM, while its accuracy is acceptable under different circumstances, such as saturation. [ABSTRACT FROM AUTHOR]

In the preliminary design of the variable flux memory motor (VFMM), it is essential to examine the magnetization characteristics of the permanent magnet (PM) according to different direct-axis current pulses, which requires numerous parametric studies. In this paper, we propose a non-linear PM load-line model for concentrated winding surface-mounted PM VFMMs by making use of the magnetic equivalent circuit method, which is valid for investigating the PM magnetization state considering non-linear magnetic characteristics. The proposed method is validated through a comparison with the results of non-linear finite-element analysis. [ABSTRACT FROM AUTHOR]

This paper presents a novel modular stator hybrid-excited synchronous machine with stator slot permanent magnets (PMs). By regulating the field current, the magnetic field, and consequently the back electromotive force, as well as the average torque can be controlled. The existence of stator slot PMs alleviates the magnetic saturation and improves the flux regulation ratio. The frozen permeability method is employed to investigate the torque contributions by different magnetic sources. Possible stator and rotor pole combinations are illustrated, and the corresponding electromagnetic performances are evaluated with the finite-element method. It is revealed that 12-stator pole machines with 11- and 13-rotor poles exhibit superior average torque and lower torque ripple due to even-order harmonics elimination. Finally, a prototype with modular stator segments is manufactured to validate the analyses and simulations. [ABSTRACT FROM AUTHOR]

This paper presents an improved finite-reluctance approach (IFRA) based on the simple synergy between reluctance network and complementary distributed magnetomotive forces (MMFs). In the IFRA, special attention is paid on the distributions of MMFs in the stator slots. Additional vertical MMFs are introduced to the local flux loop. The effects of the MMFs distribution are investigated. The comparison results among IFRA, finite-reluctance approach (FRA), and finite-element method (FEM) validate its accuracy both under linear and nonlinear conditions. Better results are obtained compared to the existing FRA, verifying its potential. [ABSTRACT FROM AUTHOR]

The main purposes of this paper consist of two parts. First, the geometric topology of novel modular spoke-type permanent-magnet (MSTPM) machines with two different magnetization modes is introduced. Second, based on the magnetic field modulation (MFM) analysis and finite-element (FE) method, the influence of magnetization mode on MSTPM machines is investigated with respect to the field harmonic, combination of stator slots and rotor poles, back electromotive force, and eletromagnetic torque. A prototype machine is manufactured and tested to verify the MFM and FE predicted results. [ABSTRACT FROM AUTHOR]

One novel 6/7 stator/rotor hybrid excitation-biased flux permanent magnet machine (HE-BFPMM) is proposed in this paper. First, it discusses the new structure and operation principle in detail. Then, one improved design optimization technique is proposed to refine the HE-BFPMM based on a 2-D finite-element algorithm. Afterward, a comprehensive electromagnetic performance comparison between HE-BFPMM and original 6/7 stator/rotor BFPMM (ORI-BFPMM) has been made quantitatively by the premise of constant out radius and axial length. It indicates that, compared with ORI-BFPMM, the HE-BFPMM can demonstrate much higher no-load back electromotive force, lower torque ripple, higher PM material utilization ratio, and stronger flux-weakening capability. [ABSTRACT FROM PUBLISHER]

This paper presents an optimal design of the rotor pole in a novel axial-flux brushless doubly fed reluctance machine (AF-BDFRM), which features higher torque and power density than its counterpart radial-flux BDFRM. The rotor span and rotor overhang lengths were the optimized parameters, with the goals of improving torque density and improving the quality of the output power, i.e., reducing the torque ripple. The optimal design process was applied to obtain the optimized shape for maximizing torque density while minimizing torque ripple in a 16 kW machine. Then, the optimal design results were verified by means of the transient 3-D finite-element analysis. Furthermore, the results of the optimally designed rotor pole were compared with those of a previously developed diamond shape. Finally, a sample prototype of one HP was selected for testing, considering the manufacturing cost and available testing facilities to verify the proper working of the novel AF-BDFRM. [ABSTRACT FROM PUBLISHER]

Novel stator slot permanent magnet (SSPM) machines with doubly salient structure have attractive features, such as a robust rotor and fail-safe capability during faults due to their peculiar PM excitation characteristics. In this paper, average electromagnetic torque production in SSPM machines is investigated using the frozen permeability analysis for the 12/10 stator/rotor pole machine. The single layer (SL) and double layer (DL) winding SSPM machines with 12/10 stator/rotor poles are further investigated, accounting for the influence of stator tooth-tips. The key findings include that the average electromagnetic torque can be enhanced by 9%–10% at the rated current for the DL and SL winding machines with stator tooth-tips. The influence of design parameters, open-circuit characteristics, inductances, electromagnetic torque, torque ripple, and losses is studied. Finally, the 2-D finite-element analysis is experimentally validated. [ABSTRACT FROM AUTHOR]

This paper proposes a new yokeless linear flux-switching permanent magnet (LFSPM) machine topology with double magnets per mover module for maximizing thrust density. The optimization and analysis for the proposed yokeless LFSPM machine are carried out by the finite-element method. The comparison between the proposed yokeless LFSPM machine and the optimized conventional yokeless machine under the same constraints is conducted, showing that the proposed machine exhibits higher thrust density and low force ripple, while the product of power factor and efficiency of the new machine is marginally higher than that of the conventional yokeless machine. [ABSTRACT FROM AUTHOR]

The transverse-flux linear switched-flux permanent magnet machine is investigated by 3-D finite-element analysis in this paper. The topology of the machine, as well as the machine operation principle, is introduced first. In order to improve the thrust force performance of the machine, two aspects are analyzed. One is the average thrust force, which is maximized by optimizing the mover stack length and the stator pole stack length. Not only does the average thrust force increase, but the force ripple slightly decreases as well. The other side is further lowering the force ripple. The segment group shift method is introduced and employed. After using this method, the force ripple has been reduced to an acceptable value, though the average thrust force will be slightly reduced. The analysis is the guidance for better understanding this novel machine. [ABSTRACT FROM AUTHOR]

This paper first presents a novel dual-layer permanent-magnet (PM)-excited (DPME) synchronous motor in which an extra set of iron teeth is employed in an inner stator between the PM rotor and the shaft. It can provide additional variation of magnetic reluctance along the circumferential direction of the air gap, and the strength of the flux modulation among the magnetic fields produced by the armature windings and the PMs is improved. The proposed motor has tactfully integrated the two pairs of flux-modulated motors inside one frame with one shared set of armature windings. The advantage of the proposed DPME motor is that it offers much higher torque capability than its conventional counterparts, making it more competitive for low-speed high-torque applications. In this paper, a novel triple-layer PM-excited (TPME) synchronous motor is further presented with the similar operating principle of the DPME, and it has three PM layers inside the frame. Finite-element method of magnetic field with mechanical motion coupled computation is employed to evaluate the electromagnetic torque precisely, showcasing that the proposed DPME motor can output an extra 37.5% more torque compared with a conventional synchronous motor, and the proposed TPME motor can output an additional 70% more torque with a similar power efficiency compared with the conventional PM synchronous motor. [ABSTRACT FROM AUTHOR]

This paper presents a simple analytical model for two types of three-phase surface-mounted permanent magnet machines: modular and unequal tooth (UNET) width machines with different slot/pole number combinations. It is based on the slotless open-circuit air-gap flux density and the slotted air-gap relative permeance calculations. This model allows calculating the opencircuit air-gap flux density, phase flux linkage, back electromotive force, and average torque of both the modular and UNET machines. Its accuracy has been validated by the 2-D finite-element (FE) method. A flux focusing/defocusing factor has also been introduced to analyze the influence of flux gaps in alternate stator teeth of modular machines on the machine electromagnetic performances. It has been found that by properly choosing the slot/pole number combination and flux gap width, the open-circuit air-gap flux density, the winding factor, and the flux focusing effect can all be improved. As a result, the performance of the modular machine can be significantly boosted. The analytical and FE models have been validated by experiments. [ABSTRACT FROM AUTHOR]

In this paper, a linear permanent-magnet vernier machine is proposed, in which both magnets and armature windings are placed in the short mover, while the long stator consists of an iron core only. Hence, it is suitable for long-stroke applications such as urban rail transit. The proposed machine integrates two magnetization directions of magnets together, which can reduce leakage flux and enhance flux density. Meanwhile, since different topologies and different slot/pole number combinations have an effect on the winding factor, several general rules are established. It is revealed that the thrust force ripple of the proposed machine is lower than its cogging force ripple, which is explained by a built analytical model. Both the analytical model and the finite-element results are validated by experiments based on a prototype machine. [ABSTRACT FROM AUTHOR]

This paper presents a method to approximately take account of the rotor excitation field of a synchronous machine under maximum aperiodic short-circuit condition using an impressed current vector potential in a 3-D transient finite-element analysis. The method is applied to compute end-region phenomena like end-winding forces or eddy current losses in conducting machine parts where the effects of the rotor excitation field cannot be neglected. A complex 3-D geometry model, the numerical method, and the computation results like end-winding forces are presented. The transient analysis of the electromagnetic field has been performed using the T, $\Phi $ - $\Phi $ formulation solved with an in-house software. [ABSTRACT FROM PUBLISHER]

This paper proposes a strategy for the optimal design of a synchronous motor with permanent magnets on the rotor surface. The proposed strategy includes several steps during which the general parameters of the rotor arrangements, currents in the stator windings, and the parameters of the slot tooth in the stator are consequently defined. The motor with the optimized cross section demonstrates significantly better performance than its initial prototype. All calculations are performed using industry-standard finite element method software. [ABSTRACT FROM PUBLISHER]

In this paper, a 10 kW/500 r/min nine-phase flux-switching permanent magnet (FSPM) machine for wind power generation system is proposed, analyzed, and designed. First, different topologies with alternative stator slots and rotor poles combinations are compared. Then, both the split ratio and rotor pole width, which have major influences on electromagnetic performance, are optimized, whereas static characteristics, viz., the phase PM flux linkage and electromotive force, cogging torque, inductance, and electromagnetic torque, are predicted by 2-D finite-element analysis (FEA). In addition, the unbalance magnetic force is investigated. Finally, a prototype of a 10 kW 36-stator-slots/34-rotor-poles nine-phase FSPM generator is manufactured and the experimental tests is carried out to verify the theoretical analysis and FEA-based predictions. [ABSTRACT FROM PUBLISHER]

In this paper, a novel three-phase bipolar stator surface-mounted permanent magnet (B-SSPM) machine with different magnetizations is proposed. The topologies and operation principles of a 6-stator-slots/8-rotor-poles B-SSPM machine are first introduced briefly, and an optimization on the key dimensions is explored to improve the characteristics of phase electromotive force and to reduce cogging torque. In addition, the influences of different magnetizations of magnets on the static characteristic of B-SSPM machines are comprehensively investigated. Finally, the predicted results are confirmed by both finite-element analysis and experiments. [ABSTRACT FROM PUBLISHER]

Flux-switching permanent magnet (FSPM) machines exhibit high torque density, high efficiency, and robust rotor structure. In this paper, a prototype of a high-power three-phase 12-stator-slot/10-rotor-pole FSPM motor used for hybrid electric vehicles (HEVs) is designed by finite-element analysis (FEA). First, the initial FEA model is improved by gradually taking into account lamination B – H curves due to different electrical frequencies, operation temperatures, 3-D end effect, and rotor eccentric. Thereafter, a modular manufacture method of the FSPM motor is discussed with the improved FEA model and validated by experimental measurements. Then, the measured overload capability of the FSPM motor is compared with that of an interior permanent magnet (IPM) motor used in Honda Civic, and the results indicate that the IPM motor exhibits significantly stronger overload capability, which is analyzed in depth from soft-iron materials, cooling conditions, and and so on. Finally, both the merits and demerits of FSPM motor employed for low-voltage and high-current HEV applications are highlighted. [ABSTRACT FROM PUBLISHER]

Axial magnetic fields leaking out at the ends of a conventional rotating synchronous machine cause losses. Therefore, it is important to be able to predict the axial magnetic fields. A linear steady-state model for the axial magnetic flux density phasor in the end regions of non-salient synchronous generators has previously been verified experimentally. This paper describes an extension of the model to salient pole synchronous generators and a method for calculating the coefficients. Experiments and 3-D finite element simulations justify a distinction between axial flux density contributions from the d and q components of the stator current. How the coefficients and the axial magnetic fields in the ends of a small synchronous generator change with steady-state operation conditions is here shown with measurements and to some extent with 3-D finite element simulations. [ABSTRACT FROM PUBLISHER]

A novel dual-stator bidirectional-flux modulated permanent magnet (PM) machine is presented in this paper. The key of the design is to locate consequent PM poles in both stator and rotor sides and the merit is that the magnetic flux produced by either the rotating or stationary PMs and dual-stator windings can be modulated by the stator teeth and rotor iron segments. It is shown that with this flux modulation effect and improved reluctance torque effect, the torque density of the machine can be increased. The bidirectional flux modulation theory and operation principle of the machine are explained and analyzed using time-stepping finite element method. [ABSTRACT FROM AUTHOR]