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A novel asymmetric interior permanent magnet (AIPM) machine is proposed in this paper. The machine's rotor consists of asymmetric poles and auxiliary flux barriers. The torque ripple of the machine is weakened by the asymmetric design of the left and right sides of the magnetic poles. The magnetic‐field‐shifting (MFS) effect improves the electromagnetic torque after adding the auxiliary flux barrier to shift the magnetic axis. The influence of critical geometrical parameters on the electromagnetic performance of the machine is investigated under the condition that the stator and permanent magnet volume remain unchanged. The relevant geometrical parameters of the machine are optimized and designed through the improved Taguchi method. The performance of the AIPM machine and the conventional machine under no‐load and load conditions are further compared by simulation analysis with finite elements, verifying the increase in electromagnetic torque and the reduction in torque ripple. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Synchronous reluctance motors offer promising advantages for industrial applications, including improved efficiency and reduced maintenance requirements. However, their widespread adoption is hindered by design complexities and performance limitations. This study focuses on addressing these challenges by developing a customized 24kW synchronous reluctance motor for industrial use, with a specific emphasis on centrifugal pumps. The research introduces a novel rotor design incorporating carefully designed flux barriers and flux carriers. Comprehensive machine analysis is conducted using the finite element method and Motor Solve software, while particle swarm optimization techniques are employed to enhance performance. Extensive simulations explore various machine parameters, and practical testing is conducted to validate the results and determine the optimized torque achievement. The results demonstrate significant improvements in the motor's performance. Compared to conventional induction motors used in similar applications, the optimized synchronous reluctance motor exhibits enhanced efficiency and smoother operation. The motor achieves notable advancements in terms of speed, efficiency, and torque characteristics, making it a valuable solution for industrial applications. The findings highlight the potential of the developed synchronous reluctance motor for industrial use. The motor design showcases excellent thermal performance, consistent steady-speed operation, and improved efficiency. This study contributes to the advancement of synchronous reluctance motor technology, showcasing its effectiveness and viability in diverse industrial settings. By addressing design complexities and optimizing performance, this research bridges the gap between the potential of synchronous reluctance motors and their practical implementation in industrial applications. Valuable insights are provided for the development of efficient and reliable synchronous reluctance motors in industrial systems.

This paper provided a mechanism of torque ripple reduction by flux barriers using field-unit type wound field motors as the subject. The field-unit type wound field motor proposed in the previous study had high torque density, but there was the problem in torque ripple characteristic. In this study, the flux barriers, which realized both maintaining average torque and reducing torque ripple, were designed using the topology optimization. Moreover, the reduction mechanism by the flux barriers were numerically analyzed based on the Maxwell stress tensor equation. The validity of the numerical verification was clarified through the experimental verification using prototype motors.

The estimation of armature reaction is of great importance in the design and operation of synchronous machines. This paper proposes a new method to reduce quadrature armature reaction in salient-pole synchronous generators. The proposed method is to reduce the quadrature axis synchronous reactance of a salient-pole synchronous generator by novel flux barrier to the rotor poles. Finite element analysis by Maxwell software was used to evaluate the nonlinearity of the synchronous reactances and to obtain the result that the quadrature axis synchronous reactance decreases when the flux barrier is introduced into the rotor pole of a salient-pole synchronous generator. As part of the study, a new flux barrier was introduced and experimented on the rotor pole of a 50 kW, 4-pole salient-pole synchronous generator without damper winding used for diesel generator. [ABSTRACT FROM AUTHOR]

This paper proposes a new consequent-pole permanent magnet vernier machine (CPMVM), which can be regarded as a combination of two conventional CPMVM with opposite polarities. Based on the simplified axial magnetic circuit model, it is verified that the proposed CPMVM can reduce the unipolar leakage flux. In order to reduce the torque ripple of machine and improve the output torque of machine, the flux barrier is placed on the rotor of the proposed machine. Then, the parameters of the proposed CPMVM are optimized and determined. Moreover, the electromagnetic performance, including no-load air-gap flux density, average torque and torque ripple, flux linkage, back-electromotive force, cogging torque, average torque, torque ripple, power factor and loss, is compared with conventional surface-mounted permanent magnet vernier machine (SPMVM) and CPMVM. Finally, it is demonstrated that proposed CPMVM with flux barrier can effectively reduce the unipolar leakage flux and greatly reduce the torque ripple of machine. Also, compared with the SPMVM, the proposed CPMVM with flux barrier saves more than 45% of the permanent magnet material without reducing output torque.

Interior permanent magnetic synchronous motors (IPMSMs) adopting concentrated windings have been widely used in industrial applications. To reduce operating costs, it is an important issue to enhance the efficiency of an IPMSM as much as possible while maintaining manufacturing costs. In general, an IPMSM used for an industrial application always operates in a specific operating area according to the required load. Therefore, this paper has two purposes. The first purpose is to propose a novel rotor structure which can enhance efficiency at the target wide-speed middle-torque operating area without additional manufacturing costs. The second purpose is to clarify the design method for a suitable rotor structure depending on its target operating area. Reducing losses is the key to enhancing efficiency. This paper first examines the effects of adopting large flux barriers and a disproportional airgap on copper and iron losses, and clarifies their merits and respective high-efficiency operating areas. Furthermore, to take advantage of the two rotor structures, a novel rotor structure which employs both large flux barriers and a disproportional airgap has been proposed. 2D-FEM (Finite-Element Method) is used for discussion first, and a prototype machine is manufactured to verify the 2D-FEM results. Both 2D-FEM and experimental results show that the proposed rotor structure can enhance the efficiency of an IPMSM most effectively at the target operating area. Moreover, for a low-speed high-torque operating area, adopting only large flux barriers is most suitable. And for a high-speed low-torque operating area, adopting only a disproportional airgap is most suitable.

This paper reviews research reported over the last three decades on enhancing the torque density of a switched reluctance machine (SRM) through improved magnetic structure of the machine. To this effect, various pole configurations, modifications to pole geometry such as introduction of teeth in stator poles, tapering of stator and rotor poles, non-uniform airgap, introduction of flux barriers in the poles, and segmental rotor are studied. All salient points in the review are supported by comparative analyses based on finite element analysis (FEA) of candidate machine designs. Increasing the number of rotor poles and introduction of teeth in stator poles enhance the torque density at low current density, while increasing multiplicity is beneficial at high current densities. Quantum of electromechanical energy conversion per individual stroke can be increased by tapering of poles, non-uniform airgap and by introduction of flux barrier in the poles. A segmental rotor can increase the stator winding flux-linkage for a given excitation, and thereby, the torque output of the machine. [ABSTRACT FROM AUTHOR]

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Synchronous reluctance motors (SynRMs) with four layers of flux barriers are currently in practical use as high-efficiency motors for industrial applications. While SynRMs have higher efficiency than induction motors, they have a high torque ripple. In this study, an asymmetric rotor structure was designed to reduce the torque ripple of the four-layer SynRM, considering the mechanical strength. Two rotor structures with different flux barrier angles were combined in the stacking direction, and the ratio of the combination was optimized by finite element analysis. In addition, prototypes of the initial structure and proposed asymmetric structure were manufactured, and their torque and efficiency characteristics were measured. The experimental results show that the proposed asymmetric structure can reduce the torque ripple while maintaining the basic characteristics such as average torque and efficiency. [ABSTRACT FROM AUTHOR]

In recent years, Synchronous Reluctance Motor (SynRM) has caught the attention of many researchers and well-known companies specializing in designing and manufacturing electric motors due to its simplicity of application. In this regard, the current study aimed to present a comprehensive approach to design a series of SynRMs using both combined methods and finite element analysis and obtain an algorithm that functions based on the similarity between the flux lines and shape of flux barriers so as to obtain both maximum torque and minimum torque ripple. To this end, a SynRM was first designed for a specific electric vehicle. Then, the case studies with different numbers of flux barriers and poles were analyzed and optimized for each case. Finally, the optimal specifications of the motors in different cases were compared and the best one was selected. Accordingly, the design parameters were identified and optimized based on Taguchi method and then, the obtained results were evaluated through finite element analysis. To achieve both maximum torque and minimum torque ripple in the power range of 150 to 750 watts, three different poles with a constant number of slots (per pole per phase) at the same size for all the described motors were considered. The validity of the proposed method was confirmed by the experimental test results. [ABSTRACT FROM AUTHOR]

Computational complexity, magnetic saturation, complex stator structure and time consumption due to repeated iteration compels researchers to adopt alternate analytical model for initial design of electric machines especially Switched Flux Machine (SFM). To overcomes the abovesaid demerits, In this article alternate analytical sub-domain model (SDM) for magnetic field computation in Segmented PM switched flux consequent pole machine (SPMSFCPM) with flux bridge and flux barriers accounting boundary and interface conditions, radial magnetized PMs (RM-PMs) and circumferential magnetized PMs (CM-PMs), interaction between stator slots and inner/outer rotor topologies is proposed. Overall field domain is divided into air gap, stator slots and Permanent Magnet (PM) accounting influence of CM/RM-PMs under no-load and on-load conditions. Analytical expression of field domain is obtained by solving magnetic vector potential utilizing Maxwell’s equations. Based on the magnetic field computation especially no-load and on-load condition, Magnetic Flux Density (MFD) components, open-circuit flux linkage, mechanical torque and cogging torque are computed utilizing Maxwell Stress Tensor (MST) method. Moreover, developed analytical SDM is validated with globally accepted Finite Element Analysis (FEA) utilizing JMAG Commercial FEA Package v. 18.1 which shows good agreement with accuracy of ~98%. Hence, authors are confident to propose analytical SDM for initial design of SPMSFCPM to suppress computation time and complexity and eliminate requirements of expensive hardware and software tools.

Synchronous reluctance machine (SynRM) is one of the candidates of high‐speed application drives. The rotor of this machine, as the most important and most challenging part of the design, has various tangential and radial ribs. Therefore, the quantity, thickness and length of the ribs are significant SynRM design parameters. If ribs' thickness is increased in order to enhance the mechanical robustness, its magnetic properties will be substantially deteriorated and vice versa. In this paper, by employing interior claws, a new rotor for SynRM is designed in a way that while increasing the mechanical robustness of the rotor for high speeds application, its magnetic characteristics enhanced, too. For this purpose, the proposed design method is applied on a two‐flux barrier rotor of a 24 stator slot SynRM. The designed machine electromagnetic performance is evaluated by finite elements method (FEM) simulation and compared with other designs. Also, the mechanical strength of the proposed rotor with two alternative claws for the speeds up to 50krpm are evaluated and confirmed by structural FE analysis. At the end, the designed interior claw rotor is prototyped and tested. Prototyped SynRM magnetic characteristics that are extracted by experiment confirmed simulations results with acceptable accuracy. [ABSTRACT FROM AUTHOR]

This article proposes a novel low-cost consequent-pole permanent magnet (CPM) synchronous machine structure, considering the reluctance torque utilization. First, a novel CPM machine with doubled salient ferromagnetic iron poles (ICP-PMSM) is proposed, featuring an N pole - iron - S pole - iron sequence to maximize the reluctance torque utilization and reduce cost. Flux barriers are integrated into the rotor structure to maintain the same magnetic rotor pole number as the conventional CPM synchronous machine (CP-PMSM). Second, for a low torque ripple, soft ferrite is used to replace part of the iron pole in the ICP-PMSM (ISCP-PMSM) to improve the air-gap flux density distribution. Furthermore, the CP-PMSM, ICP-SPMSM, and ISCP-PMSM rotors are optimized for a fair comparison. The electromagnetic performances of all the optimized machines are compared with those of a conventional surface permanent magnet synchronous machine (SPMSM). It is demonstrated that the ISCP-PMSM can obtain an almost equivalent torque and torque ripple, but with reduced PM (NdFeB) usage and cost when compared to the SPMSM.

A novel asymmetric interior permanent magnet (AIPM) machine is proposed in this paper for electric vehicle application. It has a skewed V-shape permanent magnet (PM) cavity, two PMs with different dimensions and an additional flux barrier outside the V-shape cavity in each pole. This asymmetric rotor topology can inherently utilize the magnetic-field-shifting (MFS) effect to reduce the current angle difference between the maximum PM and reluctance torque components, thereby enhancing the maximum synthetic torque with the same PM usage. The influences of cavity positions in the proposed AIPM and an existing AIPM with extra flux barrier inside the V-shape cavity are investigated and compared using finite element analysis. It is found that the proposed structure with outside flux barrier has higher average torque than the one with inside flux barrier. Both AIPM topologies are designed with the same stator, rotor diameter, and PM usage as the conventional V-shape IPM benchmark for Prius 2010. Electromagnetic, mechanical and steady-state thermal performance of three machines are compared. The results confirm that the proposed AIPM machine can achieve significant torque enhancement due to utilizing MFS effect, compared with the existing AIPM and the IPM benchmark. Finally, a small prototype of the proposed AIPM machine is designed, manufactured and tested to validate the FE analysis. [ABSTRACT FROM AUTHOR]

Mutually coupled switched reluctance motors (MCSRMs) are alternatives in the family of reluctance machines that can overcome switched reluctance motor's (SRM's) system-level integration and control challenges by utilizing standard three-phase voltage source inverters. In this article, a novel segmented-rotor, fractional-slot, tooth-wound MCSRM with notched rotor design is presented, which has very low torque ripple compared to other machine types in the SRM family. The torque ripple is reduced to 3.6% without utilizing any current profiling techniques or torque sharing functions. The ripple minimization is achieved primarily through rotor segment shaping, which has a strong influence on stator flux densities, flux linkages, and torque harmonics. The design strategy, along with the optimization details, is presented for a 120 W, 12 slot-8 pole MCSRM. The designed MCSRM is prototyped for experimental verification and validation of the finite element analysis results and design methodology. [ABSTRACT FROM AUTHOR]

This paper presents the performance of centrifugal pump coupled with synchronous reluctance motor of 24kW. The 4-pole 36 slots induction motor stator has been used for the prototype. The reduction of torque ripple and power losses is the main aim of research. Different arrangement of rotor flux barrier shapes has been tested through finite element analysis method. The rotor optimization carried out by varying different barrier edge angle, width of flux carriers, flux barriers and shaft diameter. The method of particle swarm optimization has been used by generating samples with surrogate assisted optimization technique for performance improvement of the motor. Distinct flux barrier shapes and designs have been checked through simulation. For the prototype development, final V-shaped best model is chosen. The proposed rotor shows the excellent performance in terms of reduced torque ripple and improved average torque in experimental results. The suggested design also has good thermal and mechanical performances with the capability to use in various industrial applications.

Purpose: The purpose of this paper is to investigate an alternative simplified analytical approach for the design of electric machines. Numerical-based finite element method (FEM) is a powerful tool for accurate modelling and electromagnetic performance analysis of electric machines. However, computational complexity, magnetic saturation, complex stator structure and time consumption compel researchers to adopt alternate analytical model for initial design of electric machine especially flux switching machines (FSMs). Design/methodology/approach: In this paper, simplified lumped parameter magnetic equivalent circuit (LPMEC) model is presented for newly developed segmented PM consequent pole flux switching machine (SPMCPFSM). LPMEC model accounts influence of all machine parts for quarter of machine which helps to reduce computational complexity, computational time and drive storage without affecting overall accuracy. Furthermore, inductance calculation is performed in the rotor and stator frame of reference for accurate estimation of the self-inductance, mutual inductance and dq-axis inductance profile using park transformation. Findings: The developed LPMEC model is validated with corresponding FEA using JMAG Commercial FEA Package v. 18.1 which shows good agreement with accuracy of ∼98.23%, and park transformation precisely estimates the inductance profile in rotor and stator frame of reference. Practical implications: The model is developed for high-speed brushless AC applications. Originality/value: The proposed SPMCPFSM enhance electromagnetic performance owing to partitioned PMs configuration which make it different than conventional designs. Moreover, the developed LPMEC model reduces computational time by solving quarter of machine. [ABSTRACT FROM AUTHOR]

Modularization design has been widely used to reduce the detent force of permanent magnet linear synchronous motor (PMLSM). For modular PMLSM, ideally, unit motors are independent of each other and the detent force of the whole motor is the sum of that for unit motors; thus, the whole motor's detent force can be suppressed by adjusting the phase difference among the unit motors’ detent forces. But actually, there is coupling effect between adjacent unit motors, which has adverse effect on the detent force suppression. The coupling effect changes the magnetic field distribution, which is often neglected in current research. Hence, this paper carries out the research on magnetic field analysis and flux barrier design for modular PMLSM considering the coupling effect: the influence of the coupling effect on the air gap magnetic field is clarified through magnetic field analysis; the coupling force is isolated by finite element analysis, and then the effects of key parameters are discussed; the whole motor's detent force model considering the coupling effect is established, and an optimal design method of adjusting the flux barrier length is presented to suppress the detent force. Finally, a prototype is made to test the detent force characteristics with different flux barrier lengths, which verifies the research theory in this paper. The research results in this paper can provide guidance and reference for the design of modular PMLSMs. [ABSTRACT FROM AUTHOR]

The interaction of spatial harmonics of electrical loading and the rotor anisotropy causes torque ripple in line start synchronous reluctance motor (a type of synchronous motor). A novel design technique for torque ripple reduction is presented in this study. Initially, synchronous reluctance motor filled with conducting material inside the flux barrier (called cage barrier) is optimised using a genetic algorithm (GA) technique. The optimised design is further verified using finite element analysis (FEA) and tested. To reduce the ripple content, the rotor has been introduced with an additional d‐axis cage. Six rotor structures with an additional cage have been designed and optimised using FEA. The numerical analysis results are compared for all rotor structures. The optimised rotor structures with and without d‐axis cage are fabricated and tested. Experimental results reveal that the fabricated rotor with an additional cage has reduced torque ripple and high efficiency. Finally, the acoustics test is carried out for both the fabricated structures and results are compared. [ABSTRACT FROM AUTHOR]

Transversally laminated synchronous reluctance machine (SynRM) are usually designed with multiple-layer flux barriers to achieve high electromagnetic performance. This paper summarizes three design methods to optimize the machine. Related implementation procedures are detailed. Besides, advantages and disadvantages of these methods are discussed. Based on these conventional techniques, a comprehensive optimization method is proposed, with which a prototype SynRM is designed. The performances of this prototype are discussed to verify the optimal design method.

Within the field of industry applications, the induction machine (IM) is the most used motor type, due to its robustness and line-start ability. However, the need to constrain global warming demands new sustainable technologies with high efficiency. Therefore, line-start synchronous reluctance machines could be an opportunity to achieve a high efficiency for several industry applications, especially for constant-speed drives. This paper introduces a unique rotor design for line-start synchronous reluctance machines (LSSynRMs). Additionally, the influence of the rotor bar material/resistance and the stator resistance in comparison to common IMs for industrial applications is investigated. Finite element method calculations were used for the design and the efficiency enhancement was verified using experiments. Within the context of this analysis, a 4-kW-rated IM with an efficiency rating of IE3 was chosen as a benchmark motor. The new rotor-cage design decreases the motor losses at steady state by about 28%. This promising approach could be used to upgrade IMs in industry environments instead of replacing them. Nevertheless, a challenge in the design is a good balance between the steady-state performance and synchronization capability, which in turn limits the range of industrial applications for highly efficient LSSynRMs. [ABSTRACT FROM AUTHOR]

Consequent-pole permanent magnet (CPM) machines have considerable potential for low-cost applications because they can improve the permanent magnet (PM) utilization ratio. However, the phase back electromotive force (EMF) of CPM machines with Ns/(mt) = odd (t is the greatest common divisor of the stator slot number Ns and the rotor pole-pair number p, and m is the phase number) is asymmetric, i.e., the phase back EMF has even-order harmonics, which will increase torque ripples. This paper utilized the staggered rotor to eliminate the even-order harmonics and reduce the cogging torque of CPM machines, thereby potentially decreasing torque ripples considerably. The axial flux barrier in the middle of the rotor was used and optimized using three-dimensional finite element (FE) analysis to reduce the axial leakage flux of the CPM machine with the proposed staggered rotor. Furthermore, the axial magnetized PM was embedded in the flux barrier, which improved the flux density of the airgap above the iron-pole and, consequently, further increased the output torque. The electromagnetic performance of the proposed machine, including the open-circuit airgap flux density, back EMF, average torque, torque ripples, and PM utilization, was compared with that of the conventional CPM machine. Results showed that the proposed machine obtained a similar torque and PM utilization ratio but a much lower torque ripple compared with the conventional one. [ABSTRACT FROM AUTHOR]

This paper presents a novel consequent-pole permanent magnet (PM) (CPM) machine featuring N-S-iron sequences. In order to enhance the output torque and efficiency, the flux barriers are employed to improve the magnetic symmetry and reduce the saturation of the stator yoke. The tangential magnetized PMs are embedded in the flux barriers to form the hybrid-pole PM (HPM) machine, which further improves the output torque and efficiency. The rotor of the proposed CPM and HPM machines, as well as its conventional counterpart which employing N-iron sequences, are optimized by finite element analysis. Furthermore, the electromagnetic performances of the proposed machines, including the open-circuit airgap flux density, back EMF, average torque, torque ripple, efficiency, flux-weakening capability, unbalanced magnetic force, and unipolar leakage flux, are compared with the conventional CPM machine. It is demonstrated that the proposed HPM machine can obtain almost equivalent torque, efficiency, and better flux-weakening capability when compared to the conventional one. Moreover, the proposed HPM machine has no unipolar leakage flux in the end region, and thus the magnetization of the mechanical components can be effectively reduced. Finally, a 9-slot/8-pole HPM machine is prototyped and measured to validate the analyses. [ABSTRACT FROM AUTHOR]

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

This paper presents a novel consequent-pole permanent magnet (CPM) machine featuring N-S-iron–S-N-iron sequences to eliminate the even-order harmonics of phase back electromotive force (EMF) and the unipolar leakage flux in the end region. The flux barrier is employed to improve the symmetry of the air-gap flux and reduce the saturation of the stator yoke, and hence the output torque can be improved. The proposed CPM machine, as well as its conventional counterpart with N-iron sequences, is optimized by finite-element analyses. Moreover, the electromagnetic performance of the proposed CPM machine, including the open-circuit air-gap flux density, back EMF, average torque, torque ripple, loss, efficiency, and unipolar leakage flux, is compared with the conventional CPM and surface-mounted PM (SPM) machines. Although both the proposed and conventional CPM machines have lower output torque than the SPM machine, the utilization ratio of PM material is increased by >33%. It is demonstrated that the proposed CPM machine has similar output torque and efficiency, but much lower torque ripple compared to the conventional one. Moreover, unipolar leakage flux does not exist in the end shaft of the proposed machine, and thus, the magnetization of the mechanical components can be effectively eliminated. Finally, the 9-slot/6-pole CPM machine is prototyped and measured to validate the analyses. [ABSTRACT FROM AUTHOR]

The hybrid variable-flux permanent-magnet synchronous machine (VF-PMSM) is an alternative candidate for adjustable speed applications. The series magnet and parallel magnet configurations are the two existing topologies for hybrid VF-PMSMs. However, they both have drawbacks that have not been fully resolved. A premium topology with high power density and magnetization regulation using acceptable current pulses is highly desired. This paper proposes a new hybrid VF-PMSM with a quasi-series magnet configuration and a passive flux barrier. After introducing the proposed topology and its operating principles, the results of a comparative study are presented comparing the magnetization characteristics and torque capabilities of the three configurations. The influences of key design variables on the machine’s performance are investigated, showing that the proposed machine can achieve a relatively high power density comparable to the series configuration, and the required magnetization current amplitude falls within acceptable limits. [ABSTRACT FROM AUTHOR]

In this paper, the two-layer spoke-type (TLST) axial flux interior permanent magnet (AFIPM) machine is proposed. Simple flux barriers are added to optimize the air gap flux density, in which way there is no need to change the surface of the rotor. The optimization principle is revealed and the advantages of the TLST AFIPM machine compared with the spoke-type (ST) AFIPM machine are clarified. An optimization design process based on magnetic equivalent circuit combined with idealized and improved air gap flux density waveform is proposed, in which way the calculation time is saved by avoiding an excess of finite element method (FEM) simulations. Finally, 3D FEM simulation is adopted to verify the optimization results. [ABSTRACT FROM AUTHOR]

By appropriately inserting ferrite magnets into the rotor of a synchronous reluctance motor (SynRM), the machine operational power factors and torque outputs can be improved. With specific rotor structures to accommodate those ferrites, many of these permanent-magnet-assisted SynRMs (PMA-SynRMs) have been proposed to comply the expected operational objectives. For construction convenience, the ferrites that being inserted into the flux barriers of these PMA-SynRMs are generally in rectangular shapes; hence, some adjustments on the rotor flux barriers and additional bridges are required. Such changes will inevitably affect the performance of the original SynRMs with optimized rotor structures, and these tradeoffs are thus to be recovered by parts of those adopted ferrites. This paper will provide an evaluation index that can characterize the performance of PMA-SynRMs with different volume compositions of the ferrites, along with the impact assessments of the SynRMs with modified flux barriers such that those ferrites can be properly allocated. Based on the designs obtained from thorough 3-D finite-element analyses, a 3-hp PMA-SynRM will be constructed and the related experimental measurements will also be supported to validate the design adequacies. [ABSTRACT FROM AUTHOR]

This paper deals with a detailed geometry analysis of the rotor structure for both synchronous reluctance and permanent magnet (PM)-assisted reluctance motor in order to suggest an automatic procedure to design the rotor structure. The shape of flux barriers is selected to achieve both high $d$ -axis inductance and low $q$ -axis inductance to obtain high output torque and high power factor. Methods to properly design the geometry of the ends of each barrier and PMs are adopted. In order to draw a rotor with proper shape, different modifications are discussed. All details are described to allow any reader to adopt the same procedures. After that, such a procedure is used to rapidly analyze the impact of some geometry changes on the machine performance to give a design guideline. The analyzing process starts from a reluctance motor considering the number of barriers, insulation ratio, split ratio, and slots per pole per phase. Then, the PMs are inset into flux barriers and the effect of PM width on torque, power factor, and flux weakening capability is investigated. At last, the demagnetization limit under overload operations is analyzed. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of cation exchange capacity (CEC) and location of clay nanoplatelets on the structure and performance of clay-embedded polyelectrolyte multilayer (c-PEM) membranes for wastewater effluent treatment. Two kinds of clay nanoplatelets, montmorillonite and kaolin, were deposited on the ultrafiltration membrane by employing layer-by-layer (LbL) assembly with poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA). Negatively charged clay platelets or PAA interacted with positively charged PAH to form a bilayer in the c-PEM membrane. The filtration effect of clay platelets was successively distinguished from PEM by reducing the number of (PAH/PAA) bilayers from four to one, while keeping the clay layer at the outermost layer of assembly. When the clay platelets were deposited only as the outermost layer of the LbL multilayers, the c-PEM membrane with one clay layer and one bilayer assembly showed significant flux barrier and fouling resistance. Clay platelets as the outermost layer physically increased the flow path length and decreased the number of pores, as well as effectively blocked the organic contaminants in the wastewater. Meanwhile, when the clay layer was embedded in the middle of the PEM, the synergistic effect of clay platelets and PEM for wastewater treatment was difficult to obtain because the presence of clay platelets defected the buildup of fully interdigitated c-PEM and the adsorption of clay platelets was decreased. For the clays having low CEC, a higher number of LbL multilayers were required to deposit the clay platelets and to improve the performance of membrane. The high CEC clays (montmorillonite) turned out to be better than the low CEC clays (kaolin) in the structure and performance of the c-PEM membrane for wastewater effluent treatment. [ABSTRACT FROM PUBLISHER]

In this paper, performance comparison between surface and spoke-type flux modulation (FM) permanent magnet (PM) machines is presented. Generally, spoke-array magnet arrangement is capable of increasing the torque density of PM machines due to its flux-focusing effect. Nevertheless, a flux-barrier effect is found when this magnet topology is applied in FM machines, which may offset the advantage in torque capability when the pole ratio is high. By flux distribution comparison of these two-machine topologies, the flux-barrier effect is visually explained. Through numerical FEA, this effect is further investigated in spoke-type vernier PM machines with a series of pole ratios. Finally, compared with surface-type FM machines, considerable reduction in modulated magnetic field as well as output torque capability is verified in high pole ratio, spoke-type FM machines. [ABSTRACT FROM AUTHOR]

To achieve relatively lower costs and higher operational efficiencies, without adopting permanent magnets or rotor conductors, the synchronous reluctance motor (SynRM) has received more and more attentions as a competitive solution recently. To establish a rational guidance for the related designs and constructions, this paper is aimed to present the thorough performance impact assessments of SynRMs that are composed of different electromagnetic steels at various operational specifications. Based on the magnetization and hysteresis characteristics of the steel sheets, variations of the average torques, torque ripples, and iron losses by using different stator and rotor materials are investigated, and some valuable comparison results can be provided for designers and engineers in the related motor and metal industries. [ABSTRACT FROM AUTHOR]

In this paper, the two-layer spoke-type (TLST) axial flux interior permanent magnet (AFIPM) machine is proposed. Simple flux barriers are added to optimize the air gap flux density, in which way there is no need to change the surface of the rotor. The optimization principle is revealed and the advantages of the TLST AFIPM machine compared with the spoke-type (ST) AFIPM machine are clarified. An optimization design process based on magnetic equivalent circuit combined with idealized and improved air gap flux density waveform is proposed, in which way the calculation time is saved by avoiding an excess of finite element method (FEM) simulations. Finally, 3D FEM simulation is adopted to verify the optimization results.

The main aim of this work is to present the results of the shape design optimization process of an interior permanent-magnet synchronous motor. The shape design optimization process is accomplished based on the variations of the rotor structure using the Taguchi method. The time-stepping finite-element method is used for analysis of the motor. It is found that the optimal two-layer Machaon design has the lowest torque pulsation compared with the other structures. Finally, the optimized Machaon and preliminary one-layer interior permanent-magnet synchronous motors, which are amended from industrial three-phase induction motors, are manufactured. The results of numerical, analytical, and practical tests are in good agreement. [ABSTRACT FROM AUTHOR]

This study presents a spoke‐type permanent magnet synchronous motor (STPMSM) with a novel rotor which contains four individual iron core parts with flux barriers that are designed to realise a near‐sinusoidal air gap flux density waveform. This novel type of rotor does not require thin bridges or retaining sleeves, the iron core parts of a rotor of this type are fixed to a non‐magnetic sleeve by using dovetail slots, this structure can restrict flux leakage effectively and ensure sufficient mechanical strength. The initial design parameters of a 3 kW novel motor were obtained in the initial design process first, then several key parameters were optimised by using the Taguchi method, finally a comparative analysis of the novel motor structure and the conventional STPMSM structure was performed. The comparative analysis results reveal that the novel motor structure is superior to the conventional motor structure. [ABSTRACT FROM AUTHOR]

The relationship between the well-known competitive torque density and less-competitive power factor of reluctance synchronous machines (RSMs) is investigated in this study. The investigation was carried out by implementing a complete machine model in the optimization, with varying machine-pole number and flux-barrier number combinations. Furthermore, the study consists of a multiobjective design optimization implementing a weighted-factor optimization technique. Determination of the weighting of this specific parameter relationship enables the designer to select an optimum multiobjective relationship during optimization. A specific machine was selected for analysis, then analyzed and manufactured for validation of simulation results. [ABSTRACT FROM AUTHOR]

This paper is aimed to provide the detailed design and operational investigations of synchronous reluctance motors (SynRM) that are commonly assembled by laminated electromagnetic steels. The magnetic flux paths in the SynRM rotors with various barrier and segment compositions will be analyzed, along with the generated motor torque and loss assessments. As the related mechanical cutting and/or punching processes on the rotor steels are required to achieve desired direct- and quadrature-axis reluctance ratios, their impacts to the flux paths due to saturations will also be thoroughly evaluated. Assisted by 3-D finite-element analyses, the results clearly indicated that the additional annealing process on the electromagnetic steel strips must be introduced for these SynRM designs with smaller sizes and higher efficiency requirements. [ABSTRACT FROM PUBLISHER]

This study derives a high performance flux barrier for an interior permanent magnet (IPM) motor using binary-based topology optimization (TO). TO has a higher degree of optimization than size or shape optimization. An IPM motor has many design parameters including the current phase angle, core shape of rotor and stator, and magnet position and shape. The flux barrier in an IPM motor plays a particularly important role, influencing several characteristics. We apply TO, using a multistep genetic algorithm, to the rotor core in order to determine a flux barrier with the highest torque performance. [ABSTRACT FROM AUTHOR]

This paper proposes a new design of SPOKE-type PM brushless direct current (BLDC) motor without using neodymium PM (Nd-PM). The proposed model has an improved output characteristic as it uses the properties of the magnetic flux effect of the SPOKE-type motor with an additional pushing assistant magnet and subassistant magnet in the shape of spoke. In this paper, ferrite PM (Fe-PM) is used instead of Nd-PM. First, the air-gap flux density and backelectromotive force (BEMF) are obtained based on the field model. Second, the analytical expressions of magnet field strength and magnet flux density are obtained in the air gap produced by Fe-PM. The developed analytical model is obtained by solving the magnetic scalar potential. Finally, the air-gap field distribution and BEMF of SPOKE-type motor are analyzed. The analysis works for internal rotor motor topologies. This paper validates results of the analytical model by finite-element analysis for wing-shaped SPOKE-type BLDC motors. [ABSTRACT FROM AUTHOR]

This paper derives an effective shape of the flux barrier in an interior permanent magnet (IPM) motor. IPM motors generally have many design parameters such as the current phase angle, shape of the rotor and stator's iron core, and shape and position of the magnet. The flux barrier plays an important role in controlling torque characteristics. We apply topology optimization (TO) to the rotor core using a multistep genetic algorithm to determine an effective flux barrier. Furthermore, we extend the TO to combinatorial optimization for considering its effect on the current phase angle. Thus, a reasonable flux barrier with an optimal phase angle is determined. [ABSTRACT FROM AUTHOR]