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This paper presents the efficiency improvement of a pole-changing vernier machine (PCVM) by considering the residual magnetic flux density ( B r ) of low coercivity force (LCF) permanent magnets (PMs). The PCVM operates in two modes: vernier machine (VM) mode and permanent magnet synchronous machine (PMSM) mode, achieved through pole-changing. Pole-changing involves reversing the magnetic flux direction of LCF PM to alter the number of rotor pole pairs. By changing the number of rotor pole pairs, the PCVM operates as a VM mode at low speeds, providing high torque, and as a PMSM mode at high speeds, offering high efficiency. To achieve this, a combination of high coercivity force (HCF) PM and LCF PM is utilized in a single structure. The magnetic flux direction in the LCF PM is determined by B r , and the highest efficiency is achieved when B r reaches its maximum value | B r m |. This paper focuses on improving efficiency by obtaining B r m in VM mode and − B r m in PMSM mode through the design process. Additionally, finite element analysis (FEA) is employed to compare the performance of the improved model, which considers B r , with that of the conventional model, designed without considering B r . The improved model achieves higher B r values in each mode compared to the conventional model, resulting in increased torque density. Consequently, this leads to improved efficiency. [ABSTRACT FROM AUTHOR]

This paper propose the newly structured micro permanent magnet (PM) type stepping motor with claw-poles. The micro PM type stepping motor is the preferred solution for many small electronics position determination devices since it could be miniaturized. Thus, there are growing demands for PM type stepping motors with a greater mechanical torque and a smaller size. In this paper, a newly structured micro PM type stepping motor of a 6.0-mm-outer diameter is proposed. Magnetic characteristic of the developed model in comparison with the general type model is analyzed using the three-dimensional finite element analysis (3-D FEA). Simulation and experiment are performed to verify the advantages of the developed motor. Index Terms--Claw-pole, finite element analysis (FEA), holding torque, miniaturization, PM type stepping motor.

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]

This paper presents a new rotor shape design with optimum reverse 3rd harmonic for wound field synchronous machines to effectively enhance the saliency ratio and reduce the torque ripple in a micro electric vehicle traction system. Due to the enhanced saliency ratio, the reluctance torque is expected to be improved. The air gap flux density distribution is reshaped by the new rotor shape method, which benefits the low torque ripple. By contrast, the reverse 3rd harmonic injection is much more suitable than the general 3rd harmonic injection for increasing the effective air gap length along the q-axis for a high saliency ratio. Subsequently, three amplitudes of the reverse 3rd harmonic are studied and it is found that the optimum reverse 3rd harmonic is 1/6 of the fundamental one. To verify the effectivity of the proposed design, the original model and the ICS model are compared. Finally, all the motor characteristics, such as back electromotive force, cogging torque, and electromagnetic torque, are predicted using a 2-D finite-element method with the aid of JMAG-Designer. [ABSTRACT FROM AUTHOR]

This paper deals with the design and analysis of a novel variable flux spoke-type motor (VFSM) for washing machines by focally considering the performance at the laundry and spin-drying operating modes. The key design goal is to obtain the high efficiency for the two operating modes. At the laundry mode, the ferrite and AlNiCo magnets are utilized together as the excitations to obtain a high magnetic loading, thus to obtain high torque and efficiency. At the spin-drying mode, the AlNiCo magnets are demagnetized by a pulse negative d-axis current to reduce magnetic flux density, thus to obtain low iron loss and high efficiency. The outer rotor structure with the spoke-type magnet configuration is utilized to enhance the high output performances. The D2L method is utilized to design the key parameters of the VFSM. To demonstrate the superiority of the designed VFSM, the electromagnetic characteristics are predicted by the finite element method (FEM). As a result, the volume size of the proposed VFSM is decreased by 19.4%, and the efficiency at the low-speed laundry mode is increased by 25.4%, when compared to the referenced commercial washing machine motor. [ABSTRACT FROM AUTHOR]

This paper proposes an optimal design for a surface-mounted permanent magnet motor (SPMM) to reduce torque pulsations, including cogging torque and torque ripple, by using multi-grade ferrite magnets. Based on a conventional SPMM with single-grade ferrite magnets, the proposed SPMM is designed with four-grade ferrite magnets and then optimized to minimize torque pulsations by maintaining the required torque, utilizing the Kriging method and a genetic algorithm. The results obtained by the finite element analysis show that the optimized SPMM with multi-grade ferrite magnets exhibits improved airgap flux density distribution with highly reduced cogging torque and torque ripple by maintaining the same average torque, as compared to the conventional SPMM. Furthermore, the analysis of the working points for the multi-grade ferrite magnets reveals that the optimized SPMM has good durability against the irreversible demagnetization. [ABSTRACT FROM AUTHOR]

This manuscript discusses a novel harmonic current excitation technique for a wound rotor synchronous machine based on control of the time harmonic magneto-motive force (MMF) for brushless operation. Two inverters are used to feed the armature winding in such a way that at a time, one inverter supplies the current to armature winding. The two inverters are 180° phase-shifted. The inverter assignment is based on time-division multiplexing technique to generate continuous armature currents containing reasonable third-harmonic component beside fundamental component. This third-harmonic current component generates pulsating MMF and is induced in the rotor harmonic winding; the induced current is rectified and applied to rotor field winding to generate rotor field. The rotor field interacts with armature fundamental current component for torque generation. Finite element analysis is performed to verify the idea. [ABSTRACT FROM AUTHOR]

This paper proposes an inverter scheme to generate an additional third-harmonic component alongside the fundamental component of the current. The generated third-harmonic component is used to achieve the brushless operation in a wound field synchronous machine (WFSM). Contrary to the traditional schemes used, i.e., dual inverter, single inverter with extra switches schemes, and single inverter with four transistor legs, the proposed scheme comprises a single inverter with three transistor legs that utilizes a modified third-harmonic injection pulse-width modulation. The brushless operation in WFSM requires two windings on the rotor periphery, i.e., harmonic winding and field winding that are interconnected through a rotating diode bridge rectifier. To maximize the usage of generated third-harmonic component, the selection of pole–slot combinations of the machine is carried out considering the winding factors. The proposed inverter scheme is verified in MATLAB, and a 2-D finite element analysis is used to validate the brushless operation of the machine along with its electromagnetic performance. [ABSTRACT FROM AUTHOR]

This paper presents a consequent pole changing vernier machine (CPCVM) for variable speed application such as electric vehicles. The proposed topology works as a 48-pole vernier machine with a consequent pole rotor in the low speed region. In this mode, the machine provides high torque and high efficiency. Also, the machine uses less amount of magnet volume than a surface permanent magnet machine. However, in high speed region, the poles of the machine are changed and the machine switches to permanent magnet synchronous machine (PMSM) mode that provides high efficiency in the high speed region. Therefore, the machine combines the advantages of a consequent pole vernier machine and a conventional PMSM in a single topology. The variable speed range of the machine is extended by pole changing operation. The merits of the proposed topology are investigated by finite element analysis and the feasibility of the machine is confirmed for variable speed operation. [ABSTRACT FROM AUTHOR]

This paper proposes a novel rotor strategy for the spoke-type IPM machine (STIPMM) with four surface-mounted ferrite magnets to increase torque density and decrease torque ripple. An asymmetrical rotor structure concept is used during the design process to increase the efficiency of the two torque compositions of the STIPMM, the reluctance torque and the magnetic torque. In this design, the torque is improved by ensuring that the maximum value points of the magnetic torque and the reluctance torque are closer to each other. In order to excavate the greatest potentiality of the initial model, the Kriging method and genetic algorithm are used to obtain the optimized model. To verify the analysis result, the frozen permeability method (FPM) is employed to provide feasible insights into the separation of the torque components based on a 2-D finite element method (FEM). To highlight the superiority of the initial model, a conventional STIPMM with symmetrical rotor structure is adopted for comparison under the same magnet amounts, machine size and operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents a dual-rotor permanent magnet synchronous reluctance machine (PM-SynRM) with toroidal windings to improve the magnetic torque and the utilization of two torque components, thus to obtain high electromagnetic performance, such as torque, efficiency, and power factor. To highlight the advantages of the proposed dual-rotor PM-SynRM, all of its machine characteristics, including airgap flux density, back electromotive force (EMF), torque, power, efficiency, and flux weakening capability are compared to those of a conventional PM assisted SynRM (PMA-SynRM) with the same machine size and operating conditions, with the aid of a finite element method (FEM) using the JMAG-Designer. Furthermore, the proposed dual-rotor PM-SynRM is verified to have superior endurance against the magnet irreversible demagnetization within five times of the rated current excitation. [ABSTRACT FROM AUTHOR]

A variable flux Vernier machine (VFVM) that adopts a consequent pole configuration and drum winding is proposed. To clarify the effectiveness of variable flux features in a Vernier machine, the proposed machine was investigated in terms of different aspects using the finite element method (FEM). The use of consequent pole and drum winding were intended to reduce the cost of manufacture by reducing the magnet amount to half and by reducing the end turns. The proposed machine was analyzed at variable speeds with different magnetization states of the magnets. The torque speed curves of different magnetization states were analyzed to show the wide speed range of the machine. Differences in the Vernier effect according to the magnetization state were also evaluated. Finally, it was concluded that a variable flux feature can be an effective method to widen the operating speed range of Vernier machines. [ABSTRACT FROM AUTHOR]

This paper presents the optimal design of a dual airgap spoke type permanent magnet vernier machine with dual stator dual winding (DDW) and dual stator single winding (DSW) models having an equal outer diameter and the same magnet volumes. The models were compared at a similar power and volume basis. Latin Hypercube Sampling and the Kriging Method is used to optimize the stator slots in DSW models for improved performance. 2D-Finite Element Method (FEM) was used to verify the results and compare the both models. The DSW model performs similar in terms of average torque, back EMF and shows a better performance regarding torque ripple, power factor and core loss as compared to DDW model having same dimensions on similar power and volume basis. Furthermore, DSW model has the advantage of having lesser manufacturing complexity and thermal issue posed by inner stator winding. [ABSTRACT FROM AUTHOR]

This paper presents an axial flux dual stator flux modulating synchronous machine, referred to here as axial flux modulating synchronous machine (AFMSM) for simplicity. The proposed machine has dual stators with a non-overlapped concentrated armature winding on the upper stator and field winding on the lower stator. The recently developed radial flux modulation synchronous machine (RFMSM) employs both field winding and armature winding on a single stator. Due to separate winding on different stators in the proposed AFMSM, the armature winding has more freedom of fill factor compared to single stator RFMSM. The surface current density of the proposed machine can also be doubled compared to the RFMSM due to individual winding on separate stators. Moreover, due to dual stator and axial flux topology, the rotor does not need back iron and the torque to volume ratio of the machine is rather better than single stator radial flux machine. The electromagnetic characteristics of the proposed machine are investigated using 3D finite element analysis (FEA). Two types of rotor pole shapes i.e. general shape and sinusoidal shape have been studied to improve the cogging torque and torque ripple. The performance with both kind of rotor pole shapes have been compared. The variable speed characteristics of the machine are investigated, and it is observed that the speed of the machine can be increased by adjusting the field current. [ABSTRACT FROM AUTHOR]

This paper proposes a novel hybrid-excited wound-rotor synchronous machine (HE-WRSM) with asymmetrically positioned permanent magnets (PMs) to make full use of reaction torque and reluctance torque, thus to improve the machine performance, including torque, efficiency, and power factor. To highlight the advantage of the proposed HE-WRSM, the conventional WRSM and HE-WRSM are adopted for performance comparison under the same operating conditions. All machine characteristics are predicted by the finite element method (FEM) using the commercial software, JMAG-Designer. The analysis results finally demonstrate that the proposed HE-WRSM exhibits highly improved torque, power factor, and efficiency, when compared to the conventional machines. Furthermore, the proposed HE-WRSM is verified to have superior endurance against the magnet irreversible demagnetization within two times of the rated current excitation. [ABSTRACT FROM AUTHOR]

Power transformer iron core is mainly composed of electrical sheet steel, which is easily affected by temperature, harmonic, and DC bias. So it is necessary to measure the magnetic properties of electrical sheet steel under different temperature, and DC bias. This paper presents the experiment measurement system for the 27ZH100 electrical steel sheet under different temperature and DC bias, and the magnetic field, and current in the transformer core considering the different temperature and DC bias of electrical steel sheet. Experiment are supplied to obtain the B-H curves under different temperature and DC bias, which are required for the accurate FEM (Finite element method) simulation setup. Finally, the simulation and experiment results of a transformer are verified by the experimental results under the different temperature and DC bias. [ABSTRACT FROM AUTHOR]

This paper presents a research on reducing the torque ripple in a brushless wound rotor synchronous machine (BL-WRSM). The basic brushless topology generates a third-harmonic current component in the stator to excite the rotor. The rotor has two types of windings, field winding and harmonic winding, which are connected with each other through a rotor mounted diode rectifier. Field winding has same number of poles as that of the stator armature winding to generate torque while the harmonic winding has three times the number of poles as that of the armature winding, to induce third harmonic current component and excite the field winding. In this paper, the rotor harmonic winding is split in two branches and further a capacitor is connected in series with one branch to create a phase difference. Phase difference between the two harmonic winding branches reduces the peak-to-peak value of the DC current fed to the field winding and hence the torque ripple is reduced. Finite Element Analysis (FEA) is performed to verify the reduction in ripple percentage. [ABSTRACT FROM AUTHOR]

This paper proposes a dual-stator consequent-pole permanent magnet vernier machine comprised of two stators and a sandwiched rotor. The proposed topology has high torque density owing to its special working principle and low cost due to the consequent-pole structure. To verify the superiority of the proposed machine, it is compared with an existing dual-stator vernier machine in terms of important electromagnetic characteristics. The finite-element analysis comparison of the two machines shows that the proposed machine achieves a higher average torque and a higher torque-per-magnet volume in comparison with the existing machine. Moreover, the proposed machine uses less magnet volume; therefore, the cost of the machine is significantly reduced. Furthermore, the proposed machine is more efficient compared with the existing machine. [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]

This paper proposes an optimized rotor pole shape that can effectively reduce the partial demagnetization effect and cogging torque. First, for reducing the peak amplitude of the external field that directly affects the partial demagnetization on the permanent magnets in spoke-type permanent magnet motor, we conduct a variation of core shape and insertion of a barrier. Second, with the rotor shape obtained by the first processes for reducing the partial demagnetization effect, another part of the rotor pole is varied to make better sinusoidal distributed air gap flux density to reduce the cogging torque. In the process of designing the rotor pole shape, a steepest descent method and a response surface method are applied for improving convergence. By using the finite element method, we show that the optimized rotor pole shape drastically reduces the effect of the partial demagnetization and cogging torque. [ABSTRACT FROM AUTHOR]

In this paper, a permanent magnet (PM)-less, brushless, wound-rotor vernier machine (BL-WRVM) is proposed for variable speed applications such as electric vehicles and washing machines. The wound rotor is excited through an already existing brushless topology, which requires a dual inverter configuration to generate an additional subharmonic component in the stator magnetomotive force (MMF). Different from permanent magnet vernier machines (PMVMs), the proposed BL-WRVM provides easy regulation of the rotor flux for variable speed operation. A 24-slot, 4-pole stator, and 44-pole outer rotor were designed, and 2D finite element analysis (FEA) was carried out to determine the performance of the proposed machine. To improve the performance of the proposed machine, optimization of the rotor and stator winding turns was done. The optimized model was further analyzed for wide-speed operation, and its performance was then compared with that of an equivalent permanent magnet vernier machine (PMVM). The proposed machine has the advantage of low cost due to its PM-less structure and is suitable for variable speed applications. [ABSTRACT FROM AUTHOR]

This paper proposes an optimal design for a salient pole wound field synchronous machine (WFSM) with a single flux barrier to improve torque performance and obtain a wide operating range, simultaneously. The proposed WFSM motor can effectively decrease q -axis inductance to improve the saliency ratio ( X_{d}/X_{q}) and increase the reluctance torque. To maximize the saliency ratio and improve the torque characteristics, the single flux barrier is optimized, considering the magnetic saturation that uses Kriging method based on Latin hypercube sampling and a genetic algorithm. The 2-D finite element analysis results by the aid of JMAG-Designer shows that the saliency ratio X_{d}/X_{q}$ , the reluctance torque, and the total torque of the optimal model are increased by 9.27%, 20.45%, and 6.17%, respectively, compared with those of the basic model. Finally, the performance of the optimal motor is verified through an experimental test, which indicates good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

This paper compares the performance of three different topologies of spoke-type permanent-magnet vernier machines (PMVM): 1) dual airgap dual stator winding (DSW); 2) dual airgap single stator winding (SSW); and 3) single airgap (SA). These topologies were compared in terms of torque/machine volume, cogging torque, and torque ripples. The 2-D finite element method was utilized to compare the performance of the three models. The dual airgap PMVM with a SSW showed similar performance with the same machine outer diameter and similar power in terms of torque/machine volume and torque ripples compared with the DSW model. The performance of the SSW model was better than that of the SA model for the same outer diameter and rotor. Furthermore, stator slot optimization was performed to improve torque/machine volume and reduce torque ripples in the SSW model. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a novel permanent-magnet (PM)-assisted synchronous reluctance machine (PMA-SynRM) with axially integrated magnets for improving machine performance by using a finite-element method (FEM). The proposed PMA-SynRM features a simple structure with high performance by incorporating the advantages of a SynRM and a surface-mounted PM machine (SPMM). In particular, the rotor parts of the SynRM and SPMM are assembled to make the “ $q$ -axis” located 45° (elec.) from the $d$ -axis. Thus, the magnetic torque and reluctance torque of the proposed PMA-SynRM reach the maximum values at the same current phase angle, for efficient production of the total torque. To highlight the advantages of the proposed PMA-SynRM, a conventional PMA-SynRM is adopted for comparison under the same operating conditions. The FEM analysis results finally demonstrate that the proposed PMA-SynRM has a higher total torque and power factor, as well as greatly reduced torque ripple, when compared to the conventional PMA-SynRM with the same magnet amounts. In addition, the Mises stress analysis indicates that the configuration of the proposed PMA-SynRM exhibits the advantage of avoiding stress deterioration in the rotor ribs. [ABSTRACT FROM AUTHOR]

This paper presents the design, optimization, and prototyping of a transverse flux-type-switched reluctance generator (TFSRG) with an integrated rotor consisting of the main and permanent magnet (PM) auxiliary poles. In the initial model, an integrated rotor has a simple structure, consisting of one magnet core and a yoke bar. The yoke bar was radially laminated and inserted in the rotor yoke to minimize loss of the magnetic flux, which flows along the axial direction. We analyzed the cogging torque and back-EMF characteristics of the proposed TFSRG using the finite-element analyses (FEA). The cogging torque in the analysis results for the initial model of the proposed TFSRG was relatively high cogging. To reduce a cogging torque, both corners of the stator and PM auxiliary poles were optimized using a circular fillet shape. To satisfy a design condition, the design variables of a circular fillet shape were effectively determined using the optimization algorithm, and the initial and optimal models were compared with the analyzed results by a FEA for steady state and a dynamic performance simulation for transient state, respectively. To verify the analyzed results, an optimized prototype TFSRG was manufactured and measured. The measurement results were in good agreement with analysis results, and the output performance of the prototype was verified by the experiment set. [ABSTRACT FROM PUBLISHER]

This paper proposes the optimal design of a new interior permanent magnet (IPM)-type brushless dc (BLdc) motor using low-price ferrite magnets. The new IPM motor has the structure of C-type ferrite magnets featuring a flared shape to obtain high motor performance. To maximize the flux density and minimize the torque ripple, the flared-shape rotor structure is optimized by algorithms, such as the Kriging method based on Latin hypercube sampling and a genetic algorithm. The analyses of basic and optimal designs utilize a 3-D finite-element method, and then, the validity of the optimal design is verified through fabrication of actual prototypes. [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]

This paper focuses on the design and the analysis of an ultrahigh speed axial-flux permanent magnet (AFPM) machine for an aerospace flywheel energy storage system. The superiority of the proposed AFPM machine is the material-efficient PM shape, which contributes to obtain a sinusoidal back electromotive force (back EMF) and, hence, reduces the torque pulsations of the machine such as torque ripple. The harmonics present in back EMF have a large influence on iron loss and torque pulsations, which are always unacceptable in the applications involving the speed as high as 1 000 000 r/min. Analytical modeling is first performed to determine the PM shape for the proposed models. Then, the advantages of the proposed models are verified by comparing with the basic model with the conventional ring-shaped PMs using the 3-D finite-element method. The results show that the proposed models have a nearly ideal sinusoidal back-EMF waveform that significantly reduces the torque ripples compared with the basic model. [ABSTRACT FROM AUTHOR]

This paper proposes an optimal design of a novel asymmetrical rotor structure for surface inset permanent magnet (PM) motors to obtain torque and efficiency improvement. Different from the conventional approach, the proposed design of asymmetrical rotor structures is employed to improve the torque production by creating rotor asymmetry to allow the reluctance torque and the magnetic torque to reach a maximum at the same current phase angle. To evaluate the contribution, the frozen permeability method is utilized to segregate the torque into its reluctance and magnetic torque components. For demonstrating the design concept and obtaining a criterion for improving torque by making full use of torque components, an optimal design by iterative computation is first to be performed utilizing the finite-element method. Based on the obtained criterion, the optimal design by algorithms, such as the Kriging method and genetic algorithm, is applied to further improve the torque and efficiency. As a result, the performance of the proposed surface inset PM motor by two-step optimization is dramatically improved compared with that of the conventional surface inset PM motor. Furthermore, a comparison between the optimized surface inset PM motor and a conventional surface-mounted PM (SPM) motor is also performed under the same operating condition, which demonstrates that the optimized surface inset PM motor can significantly save the magnet amount compared with the conventional SPM motor for producing the same output torque. [ABSTRACT FROM PUBLISHER]

This paper proposes an improved transverse flux type permanent magnet reluctance generator (TFPMRG) for the purpose of reducing the leakage flux and improving the back EMF. This improved TFPMRG has auxiliary rotor poles with permanent magnet (PM) added between the main rotor poles. The auxiliary rotor pole is effective to obtain high-back EMF voltage source under no-load condition and to increase the amplitude and region of the generated current under load condition. To obtain these desired performances, PMs are inserted into both ends of auxiliary rotor pole. The auxiliary rotor and main rotor poles works at the same instance under load condition. Characteristics of the improved TFPMG are analyzed using the finite element analysis and it is verified that the improved TFPMRG has an excellent performance. [ABSTRACT FROM AUTHOR]

—An improved topology for a low-speed permanent magnet vernier machine, called a dual-stator interior permanent magnet vernier machine, is introduced to significantly increase torque density and power factor. A dual-stator is adopted in the design for more torque and improving space utilization. An interior spoke-type magnet array in the rotor is designed for magnet flux focusing, which can effectively increase useful flux and force flux lines to pass through the entire machine during operation as opposed to two separate torque components as in a normal dual-stator permanent magnet machine. To clearly place the advantages of the proposed topology in perspective, the proposed dual-stator interior permanent magnet vernier machine is compared to a well-known dual-stator surface-mounted permanent magnet vernier machine. This article discusses the operation principle and magnetic field analysis of the proposed machine and reports comparison simulation results taken from the finite-element method. In addition, the stator tooth is optimized for further better performance on torque density and power factor. [ABSTRACT FROM AUTHOR]

This paper proposes a novel double-stator axial-flux spoke-type permanent magnet vernier machine, which has a high torque density feature as well as a high-power factor at low speed for direct-drive systems. The operation principle and basic design procedure of the proposed machine are presented and discussed. The 3-D finite element method (3-D-FEM) is utilized to analyze its magnetic field and transient output performance. Furthermore, the analytical method and a simplified 2-D-FEM are also developed for the machine basic design and performance evaluation, which can effectively reduce the modeling and simulation time of the 3-D-FEM and achieve an adequate accuracy. [ABSTRACT FROM AUTHOR]

This paper focuses on the design and analysis of a novel material-efficient permanent-magnet (PM) shape for surface-mounted PM (SPM) motors used in automotive actuators. Most of such applications require smooth torque with minimum pulsation for an accurate position control. The proposed PM shape is designed to be sinusoidal and symmetrical in the axial direction for minimizing the amount of rare earth magnets as well as for providing balanced axial electromagnetic force, which turns out to obtain better sinusoidal electromotive force, less cogging torque, and, consequently, smooth electromagnetic torque. The contribution of the novel PM shape to motor characteristics is first estimated by 3-D finite-element method, and all of the simulation results are compared with those of SPM motors with two conventional arched PM shapes: one previously reported sinusoidal PM shape and one step skewed PM shape. Finally, some finite-element analysis results are confirmed by experimental results. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel transverse flux type permanent magnet reluctance generator (TFPMRG), which contains a permanent magnet (PM) in its U-shaped salient stator pole. A U-shaped stator core is designed with the short flux path to reduce the mutual effect between phases. Moreover, the proposed TFPMRG shape is designed for using PM instead of an excitation circuit to provide the field excitation, which increases the output power and efficiency. Both the transverse flux type switched reluctance generator (TFSRG) and the TFPMRG are designed using 3-D finite-element analysis (FEA) and a torque equation called the D-2L method. Finally, the design results of the TFSRG and TFPMRG are confirmed with 3-D FEA. According to the results, the output power and efficiency of TFPMRG are higher than those of TFSRG. [ABSTRACT FROM AUTHOR]

In this paper, an optimal design for a concentrated flux interior permanent magnet (CFIPM) motor is proposed to improve efficiency and obtain a wide operation range simultaneously. For enhancement in efficiency in the constant torque region, the saliency ratio is increased with respect to the initial model. Two points, 3000 rpm (based speed) in the constant torque region and 7000 rpm (maximum speed) in the constant power region, are chosen so as to compare the torque in our design with that of the initial model. A 2D-finite element method (FEM) was used to calculate the inductances of the d-axis and q-axis with a change in the CFIPM rotor shape. In the optimal design, the Kriging method based on Latin hypercube sampling (LHS) and a genetic algorithm (GA) were employed. The validity of the optimal design was verified by 2D-FEM and current vector control. [ABSTRACT FROM AUTHOR]

This paper proposes a novel two-phase, two-pole, permanent magnet synchronous motor (PMSM) with dual U-core stator structure for torque ripple minimization. The proposed motor is modeled based on the conventional single-phase U-core PMSM with approximate output power and core dimension. Torque ripple in the novel motor can be reduced significantly due to 90^\circ electrical angle phase shift in two sets of magnet pairs and 90^\circ shift in two-phase excitation currents. Characteristics of both PMSMs such as back-EMF, cogging torque and electromagnetic torque are analyzed and compared by using the 3-D finite element analysis (FEA). As shown in the result, the cogging torque and torque ripple in the novel two-phase PMSM are efficiently reduced with sinusoidal back-EMF waveform and reasonable current density value. The validity of both PMSM models is also verified by the comparison between simulated and experimental measured results. [ABSTRACT FROM AUTHOR]

This paper proposes the optimization of an anisotropic ferrite magnet shape and magnetization direction to maximize back-EMF of IPM BLDC motor. Firstly, four different models of general magnet shapes are selected, and then FEM analysis is carried out with four different magnetization directions for each of four models. The best magnet shape and magnetization direction from each model are selected as an initial model for optimization. Secondly, based on the initial model, optimization design for maximum back-EMF and minimum cogging torque and THD is performed. Finally, validity and superiority of the optimization design are confirmed by manufacturing the prototype motor and performing the experiment. [ABSTRACT FROM AUTHOR]

In this paper, an optimum design for a single-phase line start permanent magnet (LSPM) motor with respect to efficiency, maximum torque, and starting torque is proposed. The design variables, objective functions, and constraints are selected for this optimum design, which is divided into three steps. Step I maximizes the rated efficiency while maintaining a balanced operation and minimizing the stator copper loss. Step II utilizes equivalent circuit analysis to consider the efficiency and the maximum torque, while Step III calculates the precise starting torque using finite element (FE) analysis. The validity of the optimum design is verified by comparing the efficiency, maximum torque, and starting torque characteristics of the time-step FE analysis with experimental results. [ABSTRACT FROM AUTHOR]

This paper deals with the modeling of a novel permanent magnet (PM) pole shape for a surface-mounted permanent magnet (SPM) motor so as to generate sinusoidal back EMF and linear electromagnetic torque. Conventional SPM motors have a square-shaped PM pole structure; therefore, square back EMF is generated along with the torque pulsations. This novel SPM motor has sinusoidal PM pole shape in the axial direction; therefore, sinusoidal back EMF is generated due to the sinusoidal magnetic flux distribution. Sinusoidal back EMF eliminates most of the cogging torque; thus, a linear electromagnetic torque is generated. Square and sinusoidal current excitation is provided as to analyze the electromagnetic torque characteristics of SPM motor models. As compared to square current excitation, sinusoidal current excitation shows better linearity as well as average electromagnetic torque for the novel SPM motor model. 3-D finite element analysis (FEA) is utilized to analyze and compare the back EMF, cogging torque, and electromagnetic torque of conventional and proposed novel PM pole shaped SPM motor models for both square and sinusoidal current excitation. [ABSTRACT FROM PUBLISHER]

This paper performs a shape optimization of a grid-connected-to-the-rotor type doubly fed induction generator (DFIG) in which the rotor winding is connected to the grid instead of the stator winding. To analyze the characteristics of a DFIG accurately, a time step 2D-FEA is carried out, which is coupled with Simplorer. To maximize the torque per weight as well as to maintain the efficiency, the Kriging model based on latin hypercube sampling and genetic algorithm are utilized. As an optimal design result, the torque per weight on the optimal model has been increased. Finally, the analysis and the optimal design results are confirmed by the experimental results. [ABSTRACT FROM PUBLISHER]

This paper attempts to design a direct driven axial flux permanent magnet synchronous generator (AFPMSG) with better accuracy considering magnetic flux leakages and fringing effect, using D^{2}L method. Design results of conventional and improved design processes are analyzed and compared using 3D finite element method (FEM). Single and multi-stack AFPMSG topologies are designed by using an improved design process. FEM structural analysis is utilized to improve power to weight ratio of three-stack AFPMSG. Finally characteristics of both single and three-stack AFPMSG topologies are analyzed and compared using 3D FEM analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a novel concentrated flux interior permanent magnet (IPM) type brushless DC (BLDC) motor that replaces low-price ferrite magnets, which has similar characteristics as the conventional IPM type BLDC motor that uses expensive NdFeB magnets. To minimize the cogging torque which is a disadvantage of the proposed model, optimal designs of rotor and permanent magnet were performed. In optimal design process, the Kriging method based on the Latin hypercube sampling (LHS) and a genetic algorithm (GA) are applied due to suitability to non-linear data. Furthermore, to improve the average torque of the proposed model, the current excitation range was changed according to inductance. Through the optimal design process and the proper current excitation range, we show that the optimal model using low-price ferrite magnets has similar performance as the conventional IPM type BLDC motor using NdFeB magnets. [ABSTRACT FROM AUTHOR]

A novel coefficient modeling technique, using a coefficient estimation method, is introduced for a brushless DC (BLDC) motor with a skewed permanent magnet and overhang structure. To construct the novel coefficient, the 3-D FEM and a design of experiment (DOE) are utilized along with the moving least square method (MLSM). Also, to verify the accuracy of the novel coefficient modeling, the conventional coefficient modeling using LSM is constructed and compared. Then the novel coefficient is combined with an approximate model constructed by 2-D FEM for use with an optimal design algorithm. For the searching process to obtain an optimal point, the genetic algorithm (GA) is used. Three-dimensional FEM simulation is used to verify the accuracy of the novel coefficient for the optimal design. [ABSTRACT FROM AUTHOR]

This paper introduces the Halbach array and an optimal design process to effectively increase thrust force and decrease the yoke volume in electro-magnetic linear actuator for fatigue and durability test machine. The finite element method is used for dynamic response analysis of the thrust, velocity and displacement. In the optimal design process, sampling points are chosen by Latin hypercube sampling and from the results, an approximation modeling is made by Radial basis function and then the optimization results are obtained by a Genetic algorithm. The simulation results are verified by experimental results. Using the optimal design process enables the optimized electro-magnetic linear actuator to effectively increase the thrust force considering the weight of linear actuator. [ABSTRACT FROM AUTHOR]

This paper presents the design of a reliable rotor shape of a BLDC motor used for reciprocating compressor considering demagnetization. Three types of rotor shape are proposed for BLDC motor and a proper rotor shape is selected by characteristic analysis using the 2D finite element method (FEM). To verify the accuracy of the analysis results, a prototype was built and tested. In order to design a reliable rotor shape against the demagnetization of the ferrite magnet, the demagnetization analysis is performed according to variation of design variables of the ferrite magnet using the 2D FEM. As a result, the BLDC motor with the developed rotor shape showed good performance to resist partial demagnetization. [ABSTRACT FROM AUTHOR]

Focuses on a study which discussed the analysis for the dynamic characteristics of a single-sided linear induction motor having the joints in the secondary conductor and the back-iron. Finite element analysis; Simulation results; Conclusion.

Presents information on a study which described the effect of eddy currents generated in the rotor steel shell of exterior-rotor type permanent magnet brushless direct current motor. Analysis model and driving method used; Finite element formulations; Results; Conclusions.

Presents information on a study which described the finite element analysis of a direct thrust-controlled linear induction motor. Information on basic direct thrust control scheme; Characteristics analysis; Results and discussion; Conclusions.

We herein propose a novel high-torque-density flux-switching permanent magnet machine (FSPMM) which adopted phase-group concentrated-coil (PGCC) winding and a cogging torque reduction technique. The PGCC winding was applied to increase the torque density. In order to maximize the torque of the FSPMM that utilizes the PGCC windings, the performance according to stator slots/rotor poles combinations were compared. A machine which had 12 stator slots and 13 rotor poles (12S13P) was selected for its top average torque value. However, the 12S13P PGCC FSPMM contains high cogging torque that must be reduced. The cogging torque reduction technique is applied, and the parameters used in the technique are further optimized to achieve the target average torque, while suppressing the cogging torque as much as possible. The optimization process was performed with a collaboration of the genetic algorithm and Kriging method. The analysis results of the optimized design exhibited huge reductions in the cogging torque and eventually in the torque ripple from the initial machine, with reasonable average torque reduction. The entire work was evaluated experimentally using a manufactured prototype. [ABSTRACT FROM AUTHOR]

This paper presents a robust optimal design method using a hybrid response surface method (H-RSM) which directly finds an optimal point satisfying a target Z-value or a probability of failure. Through three steps, this paper achieves the goal that is to increase the open-circuit airgap flux (OCAF) in a surface-mounted permanent magnet motor and decrease its variation caused by variations of the airgap lengths including an additional one between permanent magnets and rotor back yoke. First, the OCAF equation is derived from the magnetic equivalent circuit (MEC) considering the additional airgap. Then, the equation is validated by comparing its results with those of the finite element method (FEM) modeled by the slotless stator. Next, the tolerance sensitivity analysis, using the partial derivative of the OCAF equation with respect to the airgap length, is performed to investigate the effects of design variables on the OCAF. It is shown that increasing the magnet thickness is effective for both increasing mean of the OCAF and reducing its variation. Finally, robust optimal design is performed using the H-RSM, in which all data are obtained from the FEM modeled by the slotted stator. The results of the robust optimal design are verified using the FEM. [ABSTRACT FROM AUTHOR]