Search

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]

In order to simplify the manufacturing process of variable reluctance (VR) resolvers for hybrid electric vehicle/electric vehicle (HEV/EV) applications, a novel VR resolver with nonoverlapping tooth–coil windings is proposed in this paper. A comparison of the winding configurations is first carried out between the existing and the proposed designs, followed by the description of the operating principle. Furthermore, the influence of actual application conditions is investigated by finite-element (FE) analyses, including operating speed and assembling eccentricity. In addition, identical stator and windings of the novel design can be employed in three resolvers of different rotor saliencies. The voltage difference among the three rotor combinations, as well as the detecting accuracy, is further investigated. Finally, prototypes are fabricated and tested to verify the analyses. [ABSTRACT FROM PUBLISHER]

In the permanent magnet (PM)-assisted reluctance motors, low-energy PM, such as Ferrite PM, is used to get a cheap rotor. As far as the design choices are concerned, the PM width has to be selected so as to achieve the desired air-gap flux density at no-load condition and the PM thickness has to be selected to avoid the demagnetization of the PM under full-load conditions. This paper presents a practical analytical approach to compute PM width and thickness according to a given air-gap flux density and stress on the PM itself. Two approaches based on a complete model and a simplified model are considered and compared. As an example, a 36-slot 4-pole machine is designed. Finite element analysis confirms the results achieved by means of both analytical analyses. [ABSTRACT FROM PUBLISHER]

A new nonlinear lumped parameter model is proposed for a switched reluctance motor (SRM) with core losses. The components of the model and their origin are justified by finite-element simulations and experimental tests. The winding resistance and the leakage inductance are analyzed by different methods taken from the literature, and a new algorithm is proposed to overcome their shortcomings such as the nonbiunivocal flux linkage versus current relationship. In contrast to previous works, the nonlinear elements for modeling the magnetic core, such as the incremental magnetizing inductance and the core-loss resistance, are determined together and simultaneously for each value of the phase current and the rotor position. The performance of the new model and the methodology proposed for estimating its components are analyzed for different excitation types and rotor positions. The core losses are evaluated by the proposed model and by two well-known predictive models, and the results are compared to illustrate the suitability of the former. Finally, the dynamic behavior of the model, acting as an ac self-excited generator, is considered. [ABSTRACT FROM PUBLISHER]

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 presents a novel 6/5 segmental rotor-type switched reluctance motor (SRM) for cooling fan application. Unlike conventional structures, the rotor of the proposed structure is constructed from a series of discrete segments, and the stator is constructed from two types of stator poles: exciting and auxiliary poles. Meanwhile, the windings are only placed around the exciting poles, resulting in short flux paths and no flux reversal in the stator of the proposed SRM. Hence, the proposed structure may increase the electrical utilization and reduce magnetomotive force (MMF) requirement compared to conventional SRMs. To verify the proposed structure, the operation principle and the design rules of the proposed structure are illustrated and expounded. The finite-element method (FEM) is employed to get the static and dynamic characteristics of the conventional 12/8 and proposed SRMs. Furthermore, the prototype is manufactured and tested. Finally, the simulation and experimental results are presented and analyzed to verify the effectiveness of the proposed SRM. [ABSTRACT FROM AUTHOR]

A new structure for a hybrid motion switched-reluctance motor (SRM) is presented in this paper. The hybrid motion originated from the ability of the motor to operate in three modes: 1) rotary; 2) linear; and 3) rotary–linear, which can be named a new rotary–linear SRM. The design is in such a way that both rotary and linear motions can be controlled independently. The motor is composed of a three-phase 6/4 rotary SRM with Clockwise-Counterclockwise motions and a two-phase transverse flux linear SRM with forward–backward movements. The hybrid motion control does not need any decoupling control algorithm, which is an important issue in the other rotary–linear motors. In addition, a sensorless method for the motor control is provided. The motor design is performed based on the analytical approach. According to the obtained parameters, the motor 3-D model is utilized for electromagnetic assessment. The dynamic 3-D finite-element analysis is used to evaluate motor’s flux linkage, torque, speed, current, torque ripple, torque/speed, and force characteristics. The optimum operation is considered with choosing the proper dwell angle. To verify the design, a prototype is constructed in the laboratory and compared with other structures to show the performance and applicability of the proposed motor. [ABSTRACT FROM AUTHOR]

This paper proposes a model order reduction (MOR) based on the proper orthogonal decomposition (POD) to perform a fast analysis of motors. When a POD-based MOR is applied to the motor analysis, the number of basis vectors has to be increased to express the changes in the magnetic fields due to a rotational movement. Its computational efficiency is, thus, greatly deteriorated. To overcome this difficulty, the block-MOR is first applied to a motor analysis. In this method, a parameter space is subdivided into several blocks, which correspond to angular ranges in the motor analysis, in each of which the basis vectors are constructed from snapshotted fields. The computational time of the block-MOR is shown to be shorter than that of the conventional MOR, while the accuracy of both the methods is almost identical. [ABSTRACT FROM AUTHOR]

In this paper, two designs of interior permanent-magnet synchronous machine (IPMSM) for sensorless drive with absolute rotor position estimation capability are proposed. A conventional IPMSM design proposed for the same purpose had a demerit that for the absolute position estimation, the rotor should initially stroke for 100 degrees in the worst case. Using the proposed IPMSMs featuring asymmetric winding and asymmetric rotor geometry, the initial stroke of the rotor can be reduced to 30 degrees. Moreover, basic characteristics of the motor such as torque ripples and harmonics of electromotive force (EMF) are conspicuously improved. The proposed designs are evaluated by rigorous finite-element analyses and experimental tests. An analytical model of the proposed motors considering their asymmetric structures is also developed and provided in this paper. [ABSTRACT FROM AUTHOR]

This paper examines the effect of frame on the acoustic noise and vibration of a high-speed and high-power switched reluctance machine (SRM). Five types of frame/ribs are investigated, where different frame thicknesses, types of cooling ribs, and frame shapes have been analyzed. For this purpose, a 12/8 SRM has been designed at 22 000 r/min and 150 kW and two stages have been applied. In the first stage, a new equivalent stiffness of the frame is utilized in order to estimate the resonant frequencies for different frame shapes. The paper provides a mathematical calculation method and evaluates its effectiveness with finite-element simulations. The results indicate an improvement between 4% and 25% in the estimation natural frequencies. The second stage includes the vibration and acoustic noise analysis using 3-D finite-element method. Considerations for acoustic noise reduction in high-speed SRM using different frame types and cooling ribs are discussed. Particularly, radial and screw-type configurations represent a better solution to decrease the sound pressure level up to 12 dB. [ABSTRACT FROM PUBLISHER]

The inherent structure of double-stator switched reluctance motor (DSSRM) provides a significant improvement in energy conversion efficiency by eliminating the radial component of the forces. Reduction of the radial force (RF) in rotational motion increases efficiency and performance of the machine. This paper proposes and implements a new flat-type double-stator segmented cup-rotor SRM (DSSCR-SRM). In this structure, the shaft is placed on one bearing, which reduces the system cost and friction. The rotor structure is designed to be connected directly to the load (direct-drive system) without the shaft requirement. Moreover, the rotor can be balanced between two stators such that the resultant RFs is reduced to zero. Due to the difference between the number of turns in inner and outer stator-coils, the forces exerted on the segmented rotor will cause it to stay partially suspended. In order to improve the results and determine appropriate performance of the motor, the magnetic analysis has been done on a 3-D model. The results of analytical calculations and the finite-element method analyses are validated by testing a prototype model of the DSSCR-SRM. [ABSTRACT FROM PUBLISHER]

The half-teeth-wound switched reluctance machines (HT-SRMs) having single-layer concentrated windings, feature simpler structures since the coil number is half, and phase-to-phase insulations in slot are eliminated. To evaluate the effects of winding configurations, the electromagnetic performances of HT-SRMs and conventional full-teeth-wound SRMs (FT-SRMs), including air-gap flux density, coil and phase flux linkage, inductance, torque, volt–ampere, and radial magnetic force (RMF), are comprehensively compared. The results based on theoretical analysis and finite-element (FE) method reveal that HT-SRMs would exhibit higher torque per ampere when the magnetic saturations are not too severe, whereas require higher voltage supply and generate more significant RMF. Further, it is found that the fault-tolerant capabilities of HT-SRMs are superior to FT-SRMs. A pair of prototypes with identical laminations but different winding configurations are manufactured and the experimental results confirm the predictions. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to show the results of various experimental tests carried out on synchronous reluctance (REL) motors with different rotor geometries, as proposed in technical literature. The impact of the assistance of ferrite permanent-magnet (PM) inset in the flux barriers is considered: PM-assisted REL motors are compared with synchronous REL motors, highlighting the main benefits of the former solution. The effect of the rotor skewing and of adopting asymmetric geometries of the flux barriers to reduce the torque ripple is investigated by means of several tests. The impact of the lamination is also considered, as far as the overload capability is concerned. In addition to the experimental tests, a finite-element model is adopted to predict the performance of the motors. The predicted results are compared with the experimental ones in a wide operating range, showing a good agreement. [ABSTRACT FROM AUTHOR]

In-wheel motors bring a fundamental change in electric vehicle technology by removing conventional mechanical components and freeing up space inside the vehicle body. This approach ultimately helps to realize all-wheel independent control for improved vehicle dynamics and increased vehicle design freedom. However, when space allowed for an in-wheel motor is taken into consideration, high torque density, high efficiency, and wide-speed-range capability are typically required. This paper specifically investigates a 20-pole–24-slot surface permanent magnet synchronous motor with consequent pole rotor for in-wheel direct drive since this topology is well suited for high-pole motors and thus high-torque direct-drive applications. Extensive finite-element analysis is carried out to characterize the proposed motor, and the practical feasibility of the proposed motor is discussed. Finally, the validity of the analysis was experimentally verified. [ABSTRACT FROM AUTHOR]

The double-stator switched reluctance motor (DSSRM) has a potential to produce more power per volume than other types of SRMs. This paper offers a new design strategy concentrating on power rating to calculate the dimensions of a DSSRM. The new strategy is based on dissecting the DSSRM into two inner and outer rotor SRMs. In this regard, both inner and outer rotor SRMs are designed separately, and then, the results are merged together. The characteristics of the DSSRM are achieved utilizing analytical design and 3-D finite-element analysis (FEA). In addition, the obtained results are compared with dual SRM. To determine the appropriate performance of the motor, the magnetic analysis is performed utilizing a 3-D model. In addition, to achieve optimal operation, two different winding configurations are investigated and compared with each other. Finally, a prototype of the flat-type cup-shape DSSRM with a segmented rotor is fabricated and tested in the laboratory. The results of the analytical calculations and the FEA are validated by a testing motor, which show the accuracy and the design strategy, and it can be extensible to other types of motors. [ABSTRACT FROM PUBLISHER]

This paper develops an approach that is capable of accurately predicting the performance of synchronous reluctance motors (SynRMs). The SynRMs receive increasing attention and have been used in many industrial applications. The 2-D finite element analysis (FEA) is usually considered to be competent for design and analysis of SynRMs. However, the power factor of SynRMs is likely to be considerably overestimated. This would then lead to an underestimation of current required and cause problems for the design of electronic drivers. Compensation should be made to improve the accuracy of the analysis for SynRMs although there does not seem to be a solution put forward so far. The research in this paper shows that the exclusion of end turn leakage inductances in 2-D analysis is a key factor to cause such a significant difference. To resolve this problem, this paper analytically calculates the end turn leakage inductance, which is then incorporated into the 2-D FEA. The developed method is found to agree well with the experimental results, and it significantly improves the design accuracy and efficiency using only the 2-D FEA. [ABSTRACT FROM AUTHOR]

In this paper, to enhance the machine performance and realize a high-precision position control performance, a dual-loop position controller is employed for the asymmetric bilateral linear hybrid switched reluctance motor (ABLHSRM). Machine characteristics are investigated by finite-element method. The dual-loop controller is constructed by employing a tradition proportional–integral differential velocity controller as the inner loop and a fuzzy proportional differential (PD) controller for the outer loop. Experimental results demonstrate that both the position control performance and the velocity control performance under the dual-loop control algorithm are superior to the single-loop PD position control strategy. An absolute steady-state error of 4 \mu \textm can be achieved under the dual-loop control strategy. Performance comparison from the ABLHSRM and its asymmetric bilateral linear switched reluctance counterpart with the same dimensions are carried out. Position tracking results show that the rise time is improved for the proposed ABLHSRM under the proposed control scheme. [ABSTRACT FROM AUTHOR]

The parameters and antidemagnetization ability of permanent magnet-assisted synchronous reluctance motor (PMaSynRM), with concentrated and distributed windings, was analyzed by the finite-element analysis. The reason that concentrated winding PMaSynRM has worse performance in the utilization of reluctance torque and antidemagnetization ability was pointed out, compared with the distributed one. A method was proposed to further improve the antidemagnetization ability of distributed winding PMaSynRM. The magnetic circuit model of multilayer PM structure, in demagnetization case, was established. The operating point formulation, which can reach the consistency of PM layers, was deduced by solving this model. The main optimal parameters were obtained, and a prototype was made according to this method. Finally, the experimental verification of this proposed method was given. [ABSTRACT FROM AUTHOR]

With the ever rigorous operational efficiency requirements, effective copper loss reduction is one of the viable approaches for small-power alternative current motors. Among those cost-effective schemes, by eliminating the rotor windings while keeping the same stator structures, the synchronous-reluctance motor (SynRM) offers a potential substitute for those small-power applications that the induction motors are commonly adopted. Since the key factor that affects the SynRM-generated torque will be the difference between its direct-axis and quadrature-axis inductances, by arranging the rotor field paths aligned to the direct axis and by considering the possible cross-coupling magnetic saturations on the rotor ribs and segments, the performance impacts due to field path arrangements on the rotor will be thoroughly evaluated by 3-D finite-element analyses. From the experimental measurements, it is clear that the operational objectives can be achieved, and the adequacy of the proposed design guidance can then be confirmed. [ABSTRACT FROM AUTHOR]

This paper discusses a goodness index and introduces a badness factor for electric machines with a special reference to synchronous reluctance motors. This factor is then used in conjunction with a computationally efficient finite-element electromagnetic analysis and a differential evolution optimization algorithm in order to carry out a large-scale design study under comparable specifications with an induction motor. It is shown that for synchronous reluctance machines, careful rotor geometry optimization can improve the performance, and that the inherent limitations, including those for the power factor, can be systematically established. The correlations for specific average torque, copper and core losses, and efficiency are also discussed. [ABSTRACT FROM AUTHOR]

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

The practical considerations for a 50 000 r/min switched reluctance machine are studied in this paper. A novel rotor design topology with a flux bridge is proposed to reduce the windage losses at high speed. The electromagnetic characteristics of this design are analyzed in this paper. In addition, the practical problems of fabricating the prototype and testing it at high speed are discussed. Finally, experimental results are presented and compared with finite-element analysis simulation results. [ABSTRACT FROM PUBLISHER]

Switched reluctance motors (SRMs) are gaining in popularity because of their robustness, low cost, and excellent high-speed characteristics. However, they are known to cause vibration and noise primarily due to the radial pulsating force resulting from their double-saliency structure. This paper investigates the effect of skewing the stator and/or rotor on the vibration reduction of the three-phase SRMs by developing four 12/8-pole SRMs, including a conventional SRM, a skewed rotor-SRM (SR-SRM), a skewed stator-SRM (SS-SRM), and a skewed stator and rotor-SRM (SSR-SRM). The radial force distributed on the stator yoke under different skewing angles is extensively studied by the finite-element method and experimental tests on the four prototypes. The inductance and torque characteristics of the four motors are also compared, and a control strategy by modulating the turn-ON and turn-OFF angles for the SR-SRM and the SS-SRM are also presented. Furthermore, experimental results validate the numerical models and the effectiveness of the skewing in reducing the motor vibration. Test results also suggest that skewing the stator is more effective than skewing the rotor in the SRMs. [ABSTRACT FROM AUTHOR]

A magnetic hysteresis model is developed based on the vector generalization of Jiles–Atherton (JA) model combined with a simplified multiscale approach to take into account the effect of mechanical stress on the magnetic behavior. The model aims at representing electrical steel behavior under any loading configuration considering the magnetic field vector and the mechanical stress second-order tensor. Mechanical stress is introduced in the JA hysteresis model through the anhysteretic magnetization and a modified pinning parameter. The main properties of the model are shown under alternating and rotating applied induction, especially in terms of hysteresis losses. The differential magnetic susceptibility is derived from the model, and the implementation into a time-stepping finite-element method is detailed. Finally, a quasi-statically rotating switched reluctance motor is studied: considering different shrink-fitting conditions, the resulting stress is shown to have a significant effect on both distribution and global value of hysteresis losses. [ABSTRACT FROM AUTHOR]

In this paper, thermal modeling and analysis of a 10 kW double-stator switched reluctance machine (DSSRM) is presented. Thermal management is an essential step of the machine design, since overheated windings and cores might destroy the insulation and lead to failure of the machine. A three-dimensional (3-D) finite-element method (FEM) has been used to numerically calculate the temperature distribution in different parts of the machine. Furthermore, to include the use of water as coolant, computational fluid dynamics (CFD) has been utilized. Thermal performance of the prototype is then analyzed at various load conditions. A 10 kW prototype of the DSSRM has been built and the results have been experimentally verified. [ABSTRACT FROM AUTHOR]

This paper proposes the electromagnetic modeling, prototype realization, and test validation of a new quintuple-set switched reluctance motor (QSSRM) for high torque/ripples and high torque/volume applications. The proposed motor consists of five stator/rotor sets. Each set includes a collection of 4/4 stator/rotor poles, which can operate independently. In this machine, the two sets are energized to produce high torque and also decrease the torque ripple in comparison with the conventional switched reluctance machine (SRM). Five sets have robust interactions between each other in order to produce high torque for the motor. Furthermore, this QSSRM has some other advantages, such as isolated phases, better cooling, high-speed operation, and so on. The proposed QSSRM configuration is based on an optimum-design formula. First, the geometrical design parameters are presented. Then, an electromagnetic model of the machine has been simulated using 3-D finite-element analysis. A prototype motor has been manufactured and tested in the laboratory. The new structure has been compared with a traditional SRM. The experimental results and comparative study validate the proposed design operation. The test results indicate that the proposed structure offers an enhanced performance in terms of higher torque density. [ABSTRACT FROM AUTHOR]

In recent years, there is a growing interest for synchronous reluctance machines. This is due to their high torque density, flux-weakening operation capability, and high fault-tolerance capability. This paper deals with the analysis of a synchronous reluctance machine when eccentricity occurs. Both static and dynamic eccentricity are considered. An analytical model to predict the machine performance is described. As an example, a four-pole reluctance machine is analyzed, considering single, as well as multi flux-barriers per pole. The finite-element analysis confirms the results achieved by means of the proposed analytical model. [ABSTRACT FROM AUTHOR]

Referring to the analysis of the impact of the eccentricity on a synchronous reluctance motor presented in the companion paper (Part I), a comparison is carried out between rotors with symmetric and asymmetric flux-barriers. As an example, a four-pole machine with one or two flux-barriers per pole is used. In addition, the analysis is also applied to motors with fractional-slot coil windings. Both single- and double-layer windings are considered. As an example, a six-slot four-pole machine with concentrated windings and 36-slot four-pole machine with distributed windings are compared. The analytical model which is proposed in Part I is used to predict the machine performance. A finite-element analysis confirms the results achieved by means of the analytical model. [ABSTRACT FROM AUTHOR]

This paper presents for the first time the analysis and experimental validation of a six-slot four-pole synchronous reluctance motor with nonoverlapping fractional slot-concentrated windings. The machine exhibits high torque density and efficiency due to its high fill factor coils with very short end windings, facilitated by a segmented stator and bobbin winding of the coils. These advantages are coupled with its inherent robustness and low cost. The topology is presented as a logical step forward in advancing synchronous reluctance machines that have been universally wound with a sinusoidally distributed winding. The paper presents the motor design, performance evaluation through finite element studies and validation of the electromagnetic model, and thermal specification through empirical testing. It is shown that high performance synchronous reluctance motors can be constructed with single tooth wound coils, but considerations must be given regarding torque quality and the d-q axis inductances. [ABSTRACT FROM AUTHOR]

Several switched flux permanent magnet (SFPM) machines with mechanically movable flux adjusting technique are proposed, analyzed, and compared for applications which demand high speed and efficiency. By using ferromagnetic pieces-–one per every stator pole or every alternative stator pole, which are named as flux adjusters (FAs) and located on the outside surface of the stator—the airgap flux density can be weakened and therefore the operation speed range and flux weakening capability can be improved. The influence of using all or alternative FAs on the open circuit results, electromagnetic performance, and torque–speed characteristics of the SFPM machine is investigated through three SFPM machines with different stator/rotor pole combinations, i.e., 12/10, 12/13, and 12/14. Moreover, although using FAs in all stator poles can significantly improve the flux weakening capability, alternative FAs can also achieve remarkable improvement although higher torque ripple is observed. Additionally, it has been found that the 12/13 combination is considered to be the most suitable candidate for alternative FAs technique. In addition to 2-D finite-element analysis (FEA) and analytical methods, 3-D FEA results accounting for the end-effect are presented. Furthermore, experiments are performed to validate the results. [ABSTRACT FROM AUTHOR]

A novel variable reluctance (VR) resolver with nonoverlapping tooth–coil windings is proposed in this paper. It significantly simplifies the manufacturing process of multilayer windings in conventional products. Finite element (FE) analysis is used to illustrate the basic operating principle, followed by analytical derivation of main parameters and optimization of major dimensions, including air-gap length and slot opening width. Based on winding distributions and FE results, it is shown that identical stator and winding can be employed for a resolver with three different numbers of rotor poles. Further, other stator slot/rotor pole combinations based on the nonoverlapping tooth–coil windings are generalized. In addition, the influence of eccentricity and end-winding leakage on the proposed topology is investigated. Finally, a prototype is fabricated and tested to verify the analysis, including main parameters and electrical angle error. [ABSTRACT FROM AUTHOR]

This paper presents a method of profiling the phase currents to minimize the torque ripple of switched reluctance machines (SRMs) operating in four-quadrant mode over the entire speed range of operation. The method is based on machine and controller design through coupled simulation of the finite-element-based machine model and the dynamic controller model. The method considers the mutual coupling effect between conducting phases. The research quantifies the effect of sensor error and manufacturing build variations on the level of torque ripple minimization. The mitigation processes to address the issues in mass production are also presented. [ABSTRACT FROM AUTHOR]

Synchronous reluctance (SynRel) machines are gaining more and more importance in various fields of application thanks to their known merits like rugged construction, high efficiency, absence of field windings, and no or reduced need for permanent magnets. Out of the possible design variants, in this paper, SynRel motors with uniform mechanical air gap and circularly shaped flux barriers are considered and a conformal-mapping approach to their analytical modeling and simulation is proposed. A suitable conformal transformation is introduced to compute the reluctance of each rotor circularly shaped flux barrier and the result is then used to analytically determine the air-gap flux density distribution and the electromagnetic torque of the machine in arbitrary operating conditions. The accuracy of the methodology proposed is assessed against finite element analysis. [ABSTRACT FROM AUTHOR]

This paper presents a design and analysis method for a novel hybrid flux permanent-magnet (PM) machine for a high-power density. By combining radial and axial flux machines with integrated windings, the air-gap flux density is increased, and an overhang structure of the PM and additional magnetic cores are applied to increase the power density. For the analysis and design of the proposed motor, a time-consuming 3-D finite-element analysis (FEA) is required owing to its unique structure. To address this problem, a correct and rapid novel analysis method is proposed using an equivalent 2-D conversion method. The accuracy of the proposed analysis method and the usefulness of the proposed motor are confirmed via the 3-D FEA and experimental results. [ABSTRACT FROM PUBLISHER]

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]

The automated design of synchronous reluctance (SyR) motors based on multiobjective genetic optimization and finite-element analysis is considered in this paper. Three types of barrier shapes are considered, all described by an effective limited set of input variables. The three solutions are investigated to establish which of the geometries can give the best torque output and also which one represents the best compromise between output performance and computational time. The analysis presented in this paper shows that SyR motors designed automatically can give a good performance and can be designed in a reasonable time, and it is also shown that not all design degrees of freedom are useful in terms of motor performance. Two prototypes of automatically designed machines have been fabricated and experimentally compared with a third prototype designed according to state-of-the-art design principles. [ABSTRACT FROM PUBLISHER]

This paper presents the first prototype of a novel class of bearingless slice motors whose main difference from other examples of this motor topology is the absence of permanent magnets in the rotor. A homopolar permanent-magnetic-bias air-gap field is generated by stator magnets and enables passive stabilization of three degrees of freedom. This drive concept features special operational behaviors that distinguish it from other state-of-the-art bearingless drives. A prototype motor was optimized and fabricated, and measurements were conducted to verify finite-element simulation results and to prove the functionality of the drive and its nonlinear control scheme. [ABSTRACT FROM PUBLISHER]

The design of synchronous reluctance (REL) machines is complex and involves a lot of variables. It is difficult to design proper rotor flux–barrier geometry that yields satisfactory performance, in terms of torque ripple, average torque, etc. Geometry optimization is often necessary to find optimum solutions on the basis of some objective functions. However, it is not easy to determine the main impact of each geometry variable on the machine performance. The main contribution of this paper is to investigate the effect of a different level of saturation of the magnetic rotor path, comparing the performance of some synchronous REL machines. The effect of the insertion of permanent magnets is also investigated. The comparison has been carried out on the basis of finite-element analysis, considering average torque, torque ripple, power factor, torque and power versus speed curves and efficiency. A prototype has been tested to compare the simulation results with the experimental measurements. [ABSTRACT FROM AUTHOR]

An effective design method of a novel slotless resolver with a variable reluctance rotor is proposed using the finite-element method (FEM). The slotless resolver has an advantage in size, precision, and manufacturing cost over a general slot-type resolver. In designing the slotless resolver, the virtual slot section is introduced to wind the excitation coil, as well as the sin and cos output signal coils. The effective winding methods relative to coil position and coil turns in the virtual slot section are proposed to obtain precise position angle information of the resolver using FEM. To validate the proposed design method, the prototype slotless resolver with winding pattern in a flexible printed circuit board is tested, and the experimental result is compared with the simulation result. [ABSTRACT FROM AUTHOR]

This paper implements the new design structure, so-called the mechanical offset (MO) into the double-stator multitoothed switched reluctance (DS-MSR) machine to form the new MO-DS-MSR machine. The major distinction of the MO structure is to purposely mismatch the outer and inner rotor teeth with a conjugated angle. With the MO structure, the outer and the inner torque components can be compensated with each other, hence minimizing the resultant torque ripple. By employing the finite element analysis, the characteristics and performances of the proposed machines are analyzed and compared. [ABSTRACT FROM AUTHOR]

In this paper, a skewed teeth structure is proposed for the linear switched reluctance motor (LSRM). First, the normal force, as the main source of the machine deformation as well as the acoustic noise, is analyzed theoretically. Second, the skewed LSRM is designed, and the angle of the skewed structure is analyzed and optimized. Then, the normal force output of the LSRM is calculated using the finite element method (FEM), and the deformation results for the proposed machine are obtained. The relationship of the normal force and the skewed angle is derived. Finally, the experimental results demonstrate that the acoustic noise is reduced, which is a testament to the effectiveness of the proposed structure. [ABSTRACT FROM AUTHOR]

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

Switched reluctance machines (SRMs) have been comprehensively researched, and they play an important role in the modern industrial field. The topology of SRMs is quite simple and only one set of windings is employed. Consequently, the winding configuration has an essential impact on performance. In this paper, a new winding configuration for SRMs with only half-teeth wound (HT-SRM) is proposed, which is totally different from the conventional SRMs with full-teeth wound (FT-SRM). First, the basic topology and operating principle of HT-SRMs are presented by a three-phase 12/8 prototype. Then, based on the 2-D finite element analysis, an optimization of the original 12/8 HT-SRM is conducted and a series of static characteristics of three SRMs, namely, a conventional 12/8 FT-SRM, an original 12/8 HT-SRM with the same iron laminations, and an optimal HT-SRM with the optimized dimensions, are compared. Finally, three 12/8 SRM prototypes are fabricated and the experimental results verify the theoretical analysis and the corresponding finite element analysis-based predictions. [ABSTRACT FROM AUTHOR]

This paper presents a novel magnetless double-rotor flux switching motor for low cost cooling fan application. By creatively incorporating concentrated toroidal windings into a double-rotor middle-stator structure, the proposed motor not only realizes the flux switching feature, but also shortens the end-windings to improve its operational efficiency. To achieve a better performance, the motor dimensions, especially the stator and rotor pole arcs, are optimized. Meanwhile, with the introduction of a stepped air-gap, the torque at any rotor position is boosted and problems with zero output torque at starting is successfully avoided. The final optimized motor is analyzed using finite element method, and its validity is confirmed by the simulation results. [ABSTRACT FROM AUTHOR]

In this paper, stator/rotor pole combinations, winding configurations, and electromagnetic performance of novel variable flux reluctance machines (VFRMs), which employ a doubly salient structure similar to switched reluctance machines (SRMs) but with stator-located dc field windings, are investigated. VFRMs with 12 stator poles are taken as examples to illustrate the method for determining the winding connections and winding factors. The back-electromotive force (EMF), self- and mutual inductances, cogging torque, static torque, torque ripple, and unbalanced magnetic force (UMF) are investigated by finite-element analyses. It is found that many stator/rotor pole combinations, i.e., 12/8 (which may be derived from the conventional three-phase SRM), 12/10, 12/11, 12/13, and 12/14, are feasible for the 12-stator-pole VFRMs. Among these pole number combinations, the 10- and 14-rotor-pole VFRMs can eliminate the inherent UMF in 6/5 and 6/7 VFRMs and exhibit more sinusoidal back-EMF waveforms and have higher torque density than an 8-rotor-pole VFRM, whereas the 11- and 13-rotor-pole VFRMs exhibit similar torque density as the 10- and 14-rotor-pole VFRMs, but with negligible cogging torque and torque ripple, albeit with UMF. Five prototype VFRMs with 12 stator poles and different rotor poles have been designed, manufactured, and tested to verify the analyses. [ABSTRACT FROM AUTHOR]

The reluctance synchronous motor (RSM) is identified to be well suited for the variable-gear (VG) electric vehicle (EV) drive. It is shown in this paper, however, that the RSM drive's position-sensorless capability is limited at zero or very small current magnitudes due to a limited saliency magnitude. In this paper, a novel epoxy–resin-casted rotor with no iron ribs is proposed to increase the saliency of the RSM at zero reference current. This rotor RSM is simulated in finite-element (FE) analysis, built, evaluated, and compared with conventional flux barrier rotor RSMs. The effect of rotor skewing on the position-sensorless control (PSC) capability of the RSM is also evaluated by means of FE analysis and measurements. Other performance aspects are also considered in this paper. It is concluded that, overall, the skewed epoxy–resin-casted rotor RSM drive has no PSC problems in the entire load and speed regions and is well suited for VG EV drives. [ABSTRACT FROM PUBLISHER]

This paper presents the numerical modeling of a classical switched reluctance motor (SRM) and a mutually coupled SRM (MCSRM); both have three phases with 12 slots and 8 poles. The multiphysics models have been developed, which can take into account the electromagnetic characteristics, mechanical vibration, and acoustic noise of the foregoing machines. A 2-D electromagnetic model has been used to calculate the magnetic force which is the main source of vibration of the entire motor system. The vibration of the motor is calculated by a mode superposition method, while the acoustic noise is predicted by a 3-D finite-element acoustic model. In order to validate the numerical models, experiments have been carried out. A good agreement between measured and numerical results has been observed, and it is found that the vibration and the noise levels of MCSRM are considerably lower than those of classical SRM. [ABSTRACT FROM PUBLISHER]

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

This paper proposes a high force density tubular permanent-magnet (PM) motor, termed as tubular stator-PM venier motor, for artificial hearts. The novelty of the proposed motor is to artfully integrate two different magnetization directions of PMs and ferromagnetic poles together. The proposed motor incorporates the merits of vernier PM motors and stator-PM motors, offering high back electromotive force, improved force density, minimized cogging force, and reduced PM volume. The influence of the magnet pole ratio on the performance is investigated. The proposed motor is designed and compared with an existing vernier PM motor by using the time-stepping finite-element method, verifying the validation and the advantageous performance of the proposed motor. [ABSTRACT FROM PUBLISHER]

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