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This article proposes a new “switched lumped reluctance network”-based equivalent circuit for a switched reluctance motor (SRM) under saturation. The proposed circuit incorporates the effects of the position-dependent switching of the phase windings and changing position of the rotor with respect to the stator. This feature enables the analysis of non-uniform and dynamic variation of flux in motor iron sections along with that in the air gap and their effects on the phase current. The proposed model, thus, emulates the operation of an SRM, more truly, through an equivalent circuit approach. The accuracy of the proposed model is verified by comparing the analytical results of five different stator–rotor sets (having different air gaps and tooth angular widths) with the finite-element method (FEM) simulated results and found to be in excellent mutual agreement. The static and dynamic performance obtained using the proposed model has been validated by experiments on a four-phase, 1-kW, 300-V, 1000-rpm SRM. [ABSTRACT FROM AUTHOR]

In this article, a novel fault-tolerant design process of the spoke-type interior permanent magnet (IPM) motor is proposed to prevent the increase of cogging torque and torque ripple due to partial demagnetization fault and to minimize the motor size. First, unlike other research papers on the irreversible partial irreversible demagnetization of permanent magnet (PM), in this article, the effect of partial irreversible demagnetization faults on the cogging torque and torque ripple for the fault cases is investigated. Then, a novel fault-tolerant design process is proposed to solve the problem of partial demagnetization faults that increase the cogging torque and torque ripple. In the novel fault-tolerant design process, first, to solve the problem of increasing cogging torque and torque ripple due to the partial demagnetization fault, a process for implementing a uniform irreversible PM demagnetization is proposed. Second, to compensate for the motor torque constant decreased by degraded PM, which is caused by irreversible demagnetization of PM, a torque compensation coefficient is also proposed. The proposed fault-tolerant design process is applied to the motor design for the integrated electric brake (IEB) system that requires high torque density. In the optimal design process, Latin hypercube sampling (LHS), a kriging method, and a genetic algorithm are utilized. To verify the effectiveness of the proposed fault-tolerant design process, it is compared with the conventional optimized design results in which irreversible demagnetization of PM is not allowed at all to prevent the partial demagnetization faults. As a result of comparing the optimal design results, the proposed optimization model utilizing the fault-tolerant design process can significantly reduce the motor volume by 12.9%, compared to the conventional optimization model. [ABSTRACT FROM AUTHOR]

This article presents an accurate analytical model (AM) for synchronous reluctance machine (SynRM) that incorporates the effect of stator slots on the air gap flux density and torque waveforms. From the formulation of magnetic potential in the air gap for both the stator and rotor, the flux density is obtained, considering the first harmonic of the flux density and the electric loading, the average torque is calculated using the Lorentz’s force. The ripple torque is obtained from the energy stored in magnetic circuit. The method is developed for a rotor with one flux barrier per pole and then extended to a larger number of barriers. To validate the results obtained by the AM proposed finite element analysis have been carried out. Several comparisons have been derived considering different rotor positions as well as different harmonic orders, and the pros and cons of the method are highlighted. The model performs fast and can predict results with high accuracy, and can be adopted to speed up the preliminary design and optimizations of this type of motors, with respect to finite element. In addition, from the analytical expressions it is possible to obtain all the correlations between electrical, magnetic, and geometrical characteristics of the machine, with the advantage of enabling a faster machine design. [ABSTRACT FROM AUTHOR]

In this article, a method for topology optimization (TO) of a synchronous reluctance motor (SynRM) is proposed using deep reinforcement learning (RL). Due to the need for simulating a large number of finite-element models in a traditional TO task, incorporating a study involving a different problem formulation (such as a varying design domain) can be an overwhelming task. A neural network (NN)-based agent trained using an RL formulation is able to extend the knowledge from one TO design problem to other similar TO tasks. The applicability of such learning is performed using a sequence-based TO environment. It is observed that such an approach not only reduces the computation required for TO, but also introduces the capability to generalize RL to unseen TO scenarios. The proposed optimization method reduces computation time by 70%–90% when compared to a genetic algorithm-based implementation. [ABSTRACT FROM AUTHOR]

In current engineering, the skewing slots approach is commonly used for permanent magnet synchronous motor (PMSM) to reduce torque ripple and electromagnetic vibration. However, this approach may limit the axial length of the motor and increase the manufacturing cost. This article studies a segmented rotor with different pole widths approach to mitigate torque ripple and electromagnetic vibration for PMSM, which has a lower implementation cost and facilitates mechanized production. The mapping relationship between geometric dimensions and torque performance is obtained, and the optimal dimensions are determined. An 8-pole/48-slot V-shaped PMSM is taken as the original motor, and the influence of engineering error on the torque performance of the presented approach is discussed. The electromagnetic performances and vibration responses of the motor with the presented approach are compared with that of the skewing slot motor to verify the effectiveness of the presented approach. Finally, prototypes are built, and intensive experimental tests are carried out to verify the analysis and comparison. [ABSTRACT FROM AUTHOR]

This article proposes a hybrid analytical modeling procedure for the performance parameter estimation of synchronous reluctance machine, including its operation in the region of magnetic saturation. The proposed model better estimated the torque profile through improved translation and stepped transition of rotor flux barriers. The non-linear operation is simulated by considering the global saturation and estimating the machine’s operating point on the magnetization curve of the core material. The procedure formulation focuses on improving the accuracy and rapidness of the iterative design process. The obtained results are validated against an already established design analysis technique, finite-element analysis, and the frequency spectrum analysis of practical machine results. With the improved accuracy and the least requirement of simulation runtime and computational resources, the modeling procedure can be utilized as an initial design iteration tool. [ABSTRACT FROM AUTHOR]

In this article, we propose an interactive visualization method for motor design. We have proposed a visualization system for education using augmented reality (AR) and virtual reality (VR). As a further development of this, we are working on motor design as an industrial application. There are two issues in achieving high-speed interactivity. One is a fast mesh modification method in finite element analysis, and the other is a fast solving method. We propose a high-speed mesh modification method that utilizes regularly arranged grid points and coordinate transformation. In the proposed design system, the user can immediately observe the analysis result of the design change. Furthermore, if the proposed system is executed in cooperation with the projector, designers can change the design of the motor with their fingers and discuss it on the board. Furthermore, since this system can be executed on a Web browser, it can also be executed on a smartphone or tablet PC. [ABSTRACT FROM AUTHOR]

This article presents a new type of double stator swing rotating permanent magnet spherical motor (DSSRPMSM), which can realize swing, rotation, and helical motion and is used in industrial robots, gyroscopes, satellite communications, and other fields. The proposed spherical motor consists of two stators and a hollow rotor with permanent magnet (PM) poles on its inner and outer surfaces. Compared with most spherical motor with hollow coil and traditional PM synchronous motor, the structure of the motor is different and novel, and it is difficult to find a more perfect design theory and method. Thus, this article introduces the new idea of motor design in detail. First, the structure and working principle of the motor are introduced, and the original design of the motor is carried out. The 2-D rough estimation and 3-D FEM accurate simulation calculation are carried out, and the electromagnetic characteristics of the motor are obtained, including magnetic flux density distribution, torque, and loss. The simulation results meet the design specifications of the motor. A prototype was built and tested. The experimental results are in good agreement with the 3-D FEM analysis. The design method provides a theoretical basis for the design of this kind of spherical motor. The research results lay a foundation for the subsequent optimization of the motor. [ABSTRACT FROM AUTHOR]

A new partitioned stator field modulation machine (PSFMM) with H-shape permanent magnet (HPM) excitation (HPM-PSFMM) is proposed, which is evolved from the conventional flux-switching machine (FSM) and flux-reversal machine (FRM). The proposed HPM-PSFMM combines the merits of high reliability and good heat dissipation characteristic. In addition, it exhibits high torque production with low torque ripple. Based on the theory of electrical machine operation, the FSM and FRM can be transformed into PSFMM with interior permanent magnet (IPM) and surface-mounted PM (SPM) excitation by changing the position of PM excitation, respectively. It benefits to improve space utilization and increase slot area for a large number of armature windings. For reducing the flux leakage and enhancing the flux density in air gaps, the IPM and SPM excitation are combined into HPM excitation. The iron-pole rotor between the inner and outer stators acts the role of modulator to modulate the magnetic field excited by HPM excitation to couple with the armature reaction for converting electromechanical energy. The evolution process, operating principle, and key design parameters of the proposed HPM-PSFMM are presented. Finally, using the finite element analysis (FEA), it can be proven that the proposed HPM-PSFMM has the merits of high torque production, low flux leakage, low total harmonic distortion (THD), and low torque ripple when compared to other stator-PM machines, which is a desirable choice for high stability applications. [ABSTRACT FROM AUTHOR]

The magnetic field distribution in the air gap is of great importance in the design of rotary machines. In this article, an efficient analytical method is presented, which is capable of plotting the air-gap flux density waveform of induction machines (IMs) less time-consuming than the finite element method (FEM) does. The proposed method, based on the product of the current linkage waveform and the permeance waveform, utilizes the calculations of the steady-state equivalent circuit to ensure the accuracy and an equivalent air-gap reluctance model to take into account both the slot opening effect and the rotor movement. The method is tested on a general IM with different load cases and different design parameters, and the results are compared to the FEM calculations. It can be concluded that the proposed analytical method is an efficient option in the motor design to investigate the influence of the parameters on the flux density distribution. [ABSTRACT FROM AUTHOR]

The circumferential and axial widths of permanent magnet (PM) pole and E-shape stator pole of linear rotary motor with interlaced PM poles are very influential to the back electromotive force (EMF) and the flux leakage analysis is complex, which causes difficulty in optimization of the motor structure. One of the key issues in optimization design is to calculate the flux leakage accurately. In this article, the main flux and side flux variation laws of stator pole are derived by analytical method. The flux leakage can be divided into the flux leakage between the PM and the mover, flux leakage on the stator tooth tip, and the flux leakage between the adjacent PM poles and stator pole. The 3-D flux leakage calculation model is built, which is suitable for the calculation of magnetic flux based on different motor operating principles. Then the rotational and rectilinear back EMFs are calculated by analytical method, which are consistent with the results analyzed by 3-D finite element method. [ABSTRACT FROM AUTHOR]

At high gear ratios, surface permanent magnet (SPM) cycloidal magnetic gears (CyMGs) can achieve higher torque densities than SPM coaxial magnetic gears (CoMGs). This article introduces the radial flux reluctance CyMG (Rel CyMG) topology and its operating principles. The Rel CyMG replaces the permanent magnets (PMs) on an SPM CyMG’s inner rotor with salient teeth. Additionally, the Rel CyMG only requires half of the SPM CyMG’s outer rotor PM count to achieve the same gear ratio, which simplifies assembly and allows the use of wider magnets. This may improve high gear ratio designs’ manufacturability. A genetic algorithm (GA) was used with 2-D finite element analysis (FEA) to optimize Rel CyMGs, SPM CyMGs, and SPM CoMGs and demonstrate that SPM CyMGs significantly outperform the other topologies at higher gear ratios in terms of specific torque (ST) and PM ST. However, Rel CyMGs outperform SPM CoMGs at higher gear ratios, with respect to ST and PM ST. Rel CyMGs also eliminate the need for a PM retention sleeve and potentially enable the use of smaller air gaps, which can allow them to achieve slightly higher PM STs than SPM CyMGs at ultrahigh gear ratios. Employing Halbach arrays significantly improves both CyMG topologies’ ST. [ABSTRACT FROM AUTHOR]

Analytical modeling (AM) of the magnetic field for axial-flux switched reluctance motors (AFSRMs), considering 3-D features and nonlinear saturation effects, remains to be a knotty problem. This article proposes a quasi-3-D nonlinear AM method to predict magnetic field distributions and electromagnetic performances of an AFSRM. First, the harmonic modeling (HM) technique is applied to obtain the spatiotemporal distribution characteristics of the axial and tangential magnetic flux density at the mean radius. Second, the nonlinearity of the soft magnetic material in teeth is considered by an adaptive convergence rate algorithm. Finally, a radial dependence function is formulated to extend the solution of the annular Section to any point in the 3-D space of the AFSRM. To confirm the accuracy of the proposed method, the analytical solutions of magnetic flux density and electromagnetic torque have been compared with FEM simulation results. Meanwhile, an additional validation has been done for the stability of this nonlinear AM method under severe saturation conditions. Finally, the reasonable selection of the harmonic truncation order number has been discussed to reach a good balance between accuracy and time cost. The quasi-3-D nonlinear AM method can consider the curvature and edge effect, as well as the saturation effect effectively, which is suitable for performance predictions and parametric studies of AFSRMs. [ABSTRACT FROM AUTHOR]

Stator and rotor cores of interior permanent magnet (IPM) motors are usually saturated, and the saturation distribution and saturation depth vary with the stator current. Also, their rotor structures are complex; hence, the saturation cannot be accurately reflected by a saturation factor. These considerations lead to the existing equivalent air-gap length models of induction motors and inset permanent magnet (PM) motors no longer suitable for IPM motors. Therefore, based on the consideration of stator and rotor saturation, this article proposes the equivalent air-gap length model of IPM motors expressed by magnetic potentials on the stator inner surface and the rotor outer surface. The proposed equivalent air-gap length model can accurately reflect the influences of complex structure and severe saturation of IPM motors. Compared with the existing models, the proposed one is no longer uniquely determined by motor structure parameters; it is also a function of stator current and rotor position. Furthermore, the obtained equivalent air-gap length model is combined with the winding function and the modified winding function to solve the inductances under different stator currents and different rotor eccentricity states. Finally, the proposed method is verified by both finite element analysis (FEA) and experiments. [ABSTRACT FROM AUTHOR]

According to International Electrotechnical Commission (IEC) 60034-1, in industrial applications not only efficiency but also power factors are important performance indexes. When comparing line motor to induction motor (IM), a line-start synchronous reluctance motor (LS-SynRM) has a high efficiency but a low power factor than that of IM. In this article, the analysis and design of LS-SynRM are carried out considering the rotor slot opening and bridges for improving the efficiency and power factor. The reference machine is selected with a 2.2 kW IM, and the performance of the reference model is analyzed based on finite element analysis (FEA). To analyze the effect of rotor slot opening and bridges, an optimal model of LS-SynRM is designed through a two-step design process. First, the design of rotor slot for synchronization is carried out, and second, the design of barriers using the response surface method (RSM) is carried out under the same conditions of the stator size of IM. Based on the basic model, the performances of LS-SynRM are analyzed according to the slot opening and bridges. Furthermore, the parametric analysis is carried out and the final model is designed considering the efficiency and power factor based on the design parameters. Finally, the final model is manufactured, and the experiment is carried out to verify the FEA result. [ABSTRACT FROM AUTHOR]

A permanent magnet synchronous reluctance machine (PMSynRM) is studied in this article. It has a stack of surface-mounted permanent magnet (SPM) rotor and a stack of synchronous reluctance (SynR) rotor, which are axially combined on the shaft. Unlike the traditional PM-assisted SynR machine (PMASynRM), the magnets are not located in the flux barriers of the SynR rotor, and therefore, the magnets and flux barriers have no more geometric confliction between them. The two rotor stacks can be circumferentially shifted to any relative angle. Clearly, the shifting angle and the axial length ratio between the two rotor stacks, together with the phase angle of the armature current vector, influence the motor performance, and their optimal design is detailed in this article. Analysis of the prototypes shows that the studied PMSynRM evidently exhibits higher torque density than the conventional PMASynRM. [ABSTRACT FROM AUTHOR]

This work investigates the effect of design parameters of permanent magnets (PMs) and flux barriers (FBs) in the rotor on the anti-demagnetization ability (ADA) of fractional slot concentrated windings interior PM (IPM) motors for electric scooters. A 2.5 kW IPM motor (12 slots and 8 poles) is designed for a wide speed range, and its ADA associated with different PM and FB arrangements is studied under high temperature and high current density operations. The analysis shows the relationship between the ADA and characteristic current ($I_{\mathrm {ch}}$ , defined as the ratio of PM flux linkage to $d$ -axis inductance). It is also found that proper designs of FBs can significantly improve the ADA of the IPM motor without much affecting $I_{\mathrm {ch}}$. Thus, the motor ADA and performance can be simultaneously improved. Finite element analysis is used for evaluation, and experiments are conducted to validate the analysis. [ABSTRACT FROM AUTHOR]

In this article, a new two-stage harmonic current injection (TSHCI) technique is proposed for permanent magnet (PM) synchronous machines to reduce the cogging torque and torque ripple components at low speeds. The developed algorithm is validated for two different axial flux PM (AFPM) motors experimentally. It has been shown that the proposed technique help reduce the cogging components of axial gap disk motors significantly especially at very low speeds. [ABSTRACT FROM AUTHOR]

In this article, a new asymmetric PM-placed rotor topology is applied to the conventional less-rare-Earth hybrid magnet machine, where such new placement of hybrid magnets can be designed to improve the torque performance effectively. Considering the difference between the two magnetic materials, the optimal placement scheme of NdFeB-PMs and ferrite-PMs in the rotor are determined by theoretical derivation of equivalent magnetic circuit and finite element analysis. Based on the torque component separation analysis using frozen permeability method, the sizes of the two magnets are preliminarily designed to improve the utilization of reluctance torque and to reduce the superposition coupling loss of PM torque. Then, based on the parameter sensitivity analysis, the proposed asymmetric-hybrid-PM machine (AHPM) is further optimized aiming at the multi-objective of torque performance and anti-demagnetization performance. Finally, a prototype motor is fabricated and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the AHPM and the proposed design method. [ABSTRACT FROM AUTHOR]

In this article, a flux-controllable permanent magnet (FC-PM) motor has been designed and optimized to achieve the optimal torque component distribution under different flux leakage conditions. The FC-PM motor can realize flexible adjustment and control of air-gap magnetic field by a reasonable flux bridge design, which further broadens the speed range of the motor effectively. The focus of the research is to analyze and optimize the torque characteristics in combination with typical operation conditions. First, a motor topology is proposed and then the mechanism of flux leakage and the distribution of torque characteristics are studied. Then, according to different flux leakage operation conditions, an optimization method considering the torque component distribution is newly proposed. Based on the proposed optimization method, the optimal motor can be obtained. Finally, the performance of the optimal motor is analyzed and compared with the initial motor. The comparison results indicate that, based on the proposed optimization method, the torque output capability is improved effectively, while the desired leakage flux adjustment range is maintained. [ABSTRACT FROM AUTHOR]

Switched reluctance machine (SRM) has progressed as a suitable contender in the family of electrical machines for its high starting torque and better performance in different operating conditions. The need for accurate modeling of this machine is, therefore, dependent on the accurate determination of losses of which iron loss is exigent. This article aims to determine iron loss from the equivalent circuit parameters of the machine based on the input data tables that are directly obtained from the experiments carried out on an existing four-phase, bifilar wound SRM. The procedure and necessary steps for the loss separation method are well defined and supported by the theoretical and practical results. The experimental determination of the iron losses has been compared with the predicted results under the same operating conditions. [ABSTRACT FROM AUTHOR]

This article employs grain-oriented (GO) silicon steel in an axial-flux permanent magnet (AFPM) machine to improve its torque and efficiency. Rolling direction of the GO material have been studied to ensure the machine’s main magnetic flux passes through the easy magnetization direction. Based on the study of the electromagnetic characteristics of AFPM machine, GO silicon steel is laminated to form a stator according to a certain lamination direction. The torque and efficiency of the proposed machine with GO material shows an increase in comparison with that of the conventional non-oriented (NO) silicon steel machine under identical conditions. In addition, an equivalent magnetic circuit model is established to illustrate little difference of electromagnetic property under no-load condition for the yokeless stator AFPM using two kinds of silicon steel sheet. Furthermore, a AFPM machine with stator yoke is also established to highlight the superiority of GO in the application of the AFPM machine with yokeless stator. [ABSTRACT FROM AUTHOR]

This article presents a new hybrid dynamic vibration absorber (DVA) using the Coriolis effect to reduce a rotational vibration observed in various kinds of rotating machinery. The Coriolis force is generated by a linear oscillatory actuator (LOA), which reciprocates in the radial direction. The effectiveness of the proposed hybrid DVA is confirmed through a MATLAB/Simulink simulation under passive and hybrid operations of the LOA. Moreover, an active torque ripple control is also presented for the purpose of applying this DVA to a switched reluctance motor (SRM). A numerical simulation shows that the proposed hybrid DVA is able to reduce the torque ripple of the SRM by a nonsinusoidal position control of the LOA. [ABSTRACT FROM AUTHOR]

In this article, a new dual-winding dual-flux-concentrated magnetic-field-modulated brushless compound-structure machine (DDMFM-BCSM) is proposed by combining the magnetic-field modulated brushless dual-rotor machine (MFM-BDRM) and permanent magnet synchronous machine (PMSM) into one. Proposed machine has two sets of windings in stator slots and spoke-type PMs on dual rotors. Besides, there are flux barriers on the inner rotor to improve the performance of MFM-BDRM part. Based on magnetic field modulation principle, the main harmonics of the flux density in inner and outer air gap are calculated by analytical method and simulated by finite element method (FEM). The performance of the proposed machine, including MFM-BDRM part, PMSM part, and the whole DDMFM-BCSM, is analyzed. In order to analyze the influence of flux barriers on the performance of DDMFM-BCSM, a DDMFM-BCSM without flux barriers is designed to compare their performance, including torque, loss, and power factor. [ABSTRACT FROM AUTHOR]

Commonly, healthy five-phase permanent magnet assisted synchronous reluctance machines (PMaSynRMs) are modeled in harmonic fixed rotating (dq1dq) reference frames. Such approaches feature several levels of detail, namely, constant parameters or saturation in four axes, i.e., 4-D saturation or cross-saturation effects in conjunction with space harmonics in 5-D models. In this article, a 6-D model is proposed that comprises all aforementioned nonlinearities not just in faultless but also in open-phase fault conditions. Moreover, magnetic axial asymmetry introduced by discrete skew is taken into account and included in the investigated modeling. The proposed 6-D model is based on flux maps obtained from static Finite-Element program posteriori modified to comprise the skewing effect. Very close to finite-element precision is guaranteed and experimental validations have been performed to confirm the authenticity and contrast the effectiveness of the open-phase model with skew. [ABSTRACT FROM AUTHOR]

Measuring and quantifying the electromagnetic characteristics of switched reluctance motors (SRMs) are indispensable for advanced motor control and performance enhancement. This article reports on a novel method in obtaining the flux-linkage characteristics of an SRM without rotor clamping devices and position sensors. This approach combines measurement with data reconstruction. For the measuring step, flux-linkage samples at four torque-balanced positions were measured indirectly. Considering the magnetic coupling among phases, two different excitation forms were adopted to further increase accuracy. Then, for the reconstructing step, a fuzzy logic-based approach was applied to reconstruct the complete flux-linkage characteristics with measurement results. The construction results were compared to measurements results from the traditional rotor clamping method, and good agreements can be found, demonstrating the effectiveness of the proposed method. Furthermore, based on reconstructed electromagnetic characteristics, dynamic simulation of an SRM prototype under different control modes was carried out and analyzed in MATLAB. Comparison with dynamic experiments further verifies the accuracy and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Due to the significant advantages of cost savings, low temperature rises and high efficiency, synchronous reluctance machines (SynRMs) have attracted growing interest from academia to industrial applications. Numerous articles have been published to obtain a SynRM with improved performance (i.e., a high torque density and efficiency and a lower torque ripple) using different focusing points at healthy and faulty conditions such as rotor design, magnetic steel grade, stator winding, and fault tolerance control (FTC) strategy. Hence, this article reviews the scientific researches about SynRMs aiming to improve their performance. These scientific researches can be categorized into four sections: 1) optimal rotor design; 2) magnetic steel grade; 3) winding configurations; and 4) FTC strategies. [ABSTRACT FROM AUTHOR]

Many electric traction drive systems (ETDSs) are driven by electric motors primarily composed of high-energy rare-earth (RE) permanent magnets (PMs), such as neodymium–iron–boron (NdFeB) and samarium–cobalt (SmCo). Given the high cost of RE materials, there is a great interest among various industry sectors in searching for breakthrough technologies that reduce the consumption of high-energy RE magnets in their electromechanical energy conversion systems. The reduction of the magnetic volume is typically realized either by replacing a portion of the high-energy RE magnet with the low-energy ferrite magnet (knows as hybrid structure) or by modifying the magnetic arrangement of the machine itself, where a portion of the physical RE magnets is removed and replaced by induced magnets (known as consequent-magnetic pole structure). For this purpose, this article presents a review of the current state-of-the-art motor typologies with less-RE PMs and their key design challenges, followed up by a series of recommended guidelines to overcome related design challenges. [ABSTRACT FROM AUTHOR]

This article analyses the electromagnetic performance of dc-biased current vernier reluctance machines (DCB-VRMs) with distributed windings. Taking example of 12-stator slot machines, the coil connection and current configuration are illustrated. Moreover, the back electromotive force (EMF), torque capability, etc., are analyzed by finite-element analysis (FEA). In addition, the torque density of DCB-VRMs equipped with distributed and nonoverlapping windings are compared. The results show that some combinations of distributed winding machines present a higher torque capability thanks to the higher pole ratio. [ABSTRACT FROM AUTHOR]

Due to the flux leakage and large detent force, the thrust force ripple of transverse-flux linear motor is relatively large, which restricts its further application. Also, the field of most existing transverse-flux machines is hard to be altered and regulated considering the permanent magnet (PM) excitation. Therefore, to suppress the force ripple and strengthen the flux regulation capability of transverse-flux machines, a novel hybrid excitation transverse-flux tubular motor with complementary structure is proposed in this article. The key is that a complementary and parallel structure is constructed in this motor, and hybrid excitation of both dc windings and small auxiliary PMs installed at opening of the slot is adopted in this motor as well. In addition, unequal teeth design of dc winding and ac winding is also employed to increase the thrust force density. Finite element calculation results verify the effectiveness of the proposed machine. [ABSTRACT FROM AUTHOR]

To solve the coupling between torque and suspension force in the conventional bearingless switched reluctance motor (BSRM) and improve suspension performances, the novel hybrid stator type bearingless switched reluctance motor (HSTBSRM) with double-slice structures is proposed. The torque magnetic circuit is completely independent of the suspension magnetic circuit, and the natural decoupling between the torque and suspension force is achieved. First, the structure, magnetic circuits, suspension, and rotation mechanism are analyzed. The mathematical models of radial suspension forces are deduced in detail. According to the maximum radial bearing capacity, the main parameters of the suspension part are designed. Finally, the 3-D finite-element analysis is carried out to verify the magnetic circuit, suspension mechanism, and models. [ABSTRACT FROM AUTHOR]

High-speed machines exhibit the advantages of super-high-power density, high efficiency, etc. and have been gaining more research attention in recent years. This article proposes an elaborate high-speed vernier reluctance machine (HSVRM) topology. The main advantages are as follows: (1) the stator adopts the so-called half-quasi-squirrel cage winding so that one side of all conductors is short connected and the other side is powered by modular inverter, (2) dc-biased current is fed into each conductor independently so that the machine can operate with the principle of magnetic field modulation, and (3) ladder rotor is equipped to weaken the torque ripple of the machine. Obviously, the machine topology significantly resolves the shortage of overlong end length and improves the fault-tolerant ability. In this article, the basic principle and electromagnetic characteristics of the machine will be analyzed by finite element analysis (FEA). [ABSTRACT FROM AUTHOR]

This article proposes a novel topology optimization method using the Gabor filter, which is widely used in the field of image processing. The proposed method is applied to the optimization of a synchronous reluctance motor; its average torque is maximized, and simultaneously, the torque ripple is minimized. It is shown that the proposed method results in a motor with thin layer-shaped flux barriers, which achieves a better torque performance in comparison with a conventional model and a motor optimized using normalized Gaussian network (NGnet). [ABSTRACT FROM AUTHOR]

In this article, an exhaustive comparison is presented between two types of model order reduction methods, namely the proper orthogonal decomposition (POD) and the orthogonal interpolation method (OIM), for the characterization of a switched reluctance machine. The purpose of the comparison is to find out the best practices for the design of the machine control parameters and strategy. The control design itself is not presented here, but the needed information is at the focus. The comparison is based on the computation time and the complexity of the reduced-order model as well as the accuracy of the needed data as compared with the one obtained from the full-order model. The results show that OIM is more efficient in terms of calculation time, especially when considering a nonlinear problem. [ABSTRACT FROM AUTHOR]

This article presents a quasi-3-D analytical model for double-sided axial-flux permanent magnet machines (AFPMMs) with coreless structures. A simple, fast, and accurate technique is developed to calculate flux densities in different parts of the AFPMM combining the solution of Maxwell’s equations and the magnetic equivalent circuit (MEC). In this technique, Maxwell’s equations are used to generate flux sources that are used in the reluctance network of the MEC. After calculating all the reluctances and flux sources, the magnetic flux densities are obtained. This method takes into account the effects of permanent magnet (PM) reluctance, leakage flux between PM-to-PM, PM-to-rotor leakage flux at different PM edges, and the fringing flux effect. By considering these leakage fluxes as a factor called variation function in the design procedure of the machine, the analysis time is dramatically reduced compared to numerical methods while maintained high reliability. It should be noted that since considering saturation phenomenon effects in coreless AFPMM analysis does not give rise to significantly different performances, they are not included in the proposed model. Furthermore, the machine’s main features, such as the axial and tangential components of the no-load flux density in the air-gap and stator areas, as well as the back electromotive force (EMF), are derived by using magnetic field solutions and simple equivalent circuits. Finally, to validate the accuracy of the proposed method, the analytical results are compared to the case that no leakage fluxes are included in the analytical model and to the 3-D finite-element analysis (FEA) in terms of computation time and accuracy. [ABSTRACT FROM AUTHOR]

A bearingless machine should be designed to maximize the average and to minimize the ripple in the electromagnetic torque and levitating force. In a bearingless synchronous reluctance machine (BSynRM), the complex rotor design and the levitation winding create a rich spatial and temporal spectrum of the magnetic flux density in the airgap, which affects both the torque and force ripple. In this article, a novel method is introduced to compute the electromagnetic forces from the spatial harmonics of the airgap flux density. A new indexing method is introduced to classify the spatial harmonic wavenumbers and temporal harmonic frequencies of the flux density in the electromagnetic force. The proposed model enables the understanding of the spatial harmonic footprint on the temporal frequencies of the electromagnetic force ripple. The study is carried out through finite element simulations, which are verified by prototype measurements. [ABSTRACT FROM AUTHOR]

This article presents an analysis on the field weakening capability of a flux intensifying synchronous motor (FI-SM) with a small quantity of inset permanent magnets (PMs) on the rotor surface. Differing from other FI-SMs whose rotors are constructed by interweaving PMs and flux barriers (FBs), for the presented FI-SM, the PM dimensions can be easily adjusted without significantly altering the rotor configuration, thus offering more flexibility in rotor design and making it more feasible to analyze the influence of the added PM on flux density distribution, inductances, PM flux linkage, and field weakening capacities in conjunction with armature current. This article, through investigating this design potential, aims to provide an approach for design and analysis of this type of motor to enhance the performance and improve the field weakening capability. Experiments are conducted to validate the simulation. [ABSTRACT FROM AUTHOR]

This article proposes a new coil arrangement for a four-phase switched reluctance motor (SRM) which can be applied to a 12-slot and its multiple-slot motors. Two patterns of coil arrangement for a four-phase SRM have been proposed. However, these coil arrangements can be applied for eight-slot and its multiple-slot motors because of their magnetic symmetry. The conventional and proposed coil arrangements are compared in a four-phase SRM with 24 slots. The torque and radial force characteristics are compared using finite-element analysis. Finally, the motor efficiency is compared. [ABSTRACT FROM AUTHOR]

This article proposes a new position estimation method based on an unsaturated flux linkage model for planar switched reluctance motors (PSRMs). The bipolar-voltage-injection method is used to measure the flux linkage, and it is found that ripples caused by iron loss and aluminum eddy current with different amplitudes appear at the troughs of the flux curve. The effect of the losses on the flux linkage measurement is revealed in this article, and the loss compensation models are built based on the analysis. The improved flux linkage model is proposed with the loss compensation models. Then, the position estimation method is given with the improved flux linkage model. Flux linkage measurement result shows that the model with loss compensation has higher accuracy than the conventional model. Initial and planar-motion position estimation experiments are carried out for the PSRM. The initial position estimation error is from −0.4 to 0.4 mm. The planar-motion position estimation errors are from −1.1 to 1.1 mm in the ${X}$ -axis and from −1.2 to 1.0 mm in the ${Y}$ -axis, and the effectiveness of the proposed flux linkage model is verified. [ABSTRACT FROM AUTHOR]

In this article, a new type of flux-intensifying permanent magnet (FI-PM) motor is designed, analyzed, and optimized. It focuses on the low-speed operation condition of electric vehicles (EVs). The key characteristic of this motor is the feature of the reverse saliency, so that it not only utilizes the positive reluctance under the positive $d$ -axis current but also improves the PM operation point under maximum torque per ampere (MTPA) control strategy. The relationships among the key parameters, reverse saliency, and torque performance are analyzed and investigated. The response surface method is used to optimize the motor performances. Then, for a better presentation of the investigated motor, the motor performances are evaluated and compared with the traditional interior permanent magnet motor (IPM) in torque characteristic and irreversible demagnetization ability. Finally, for the experimental validation, the prototyped motor is manufactured and tested. [ABSTRACT FROM AUTHOR]

The amorphous alloy material has the characteristics of high resistivity and low loss, but the loss characteristic of the amorphous alloy core is unstable, which can be greatly affected by the processing. Thus, the calculation error of the amorphous alloy core loss turns out to be large, which leads to the difficulty in the design and optimization of the core. In this article, a new loss factor correction model of the amorphous alloy core is proposed to analyze the influence of the processing and core size on the loss. To verify the loss factor correction model, the loss characteristic of amorphous alloy material was tested and analyzed, and the core loss at different core sizes was compared. In addition, a mathematical model of core loss is proposed for the amorphous alloy stator core to optimize and calculate the loss of amorphous stator core. The correctness of the proposed model is verified by the test of core loss. [ABSTRACT FROM AUTHOR]

This article aims to implement a fan motor design with an airfoil-shaped rotor via the newly developed 3-D printing method. This integrated design is originated from a flux-switching permanent magnet motor, in which the motor rotor can directly produce airflow without any external impellers. Such a design and manufacturing process can effectively enhance the robustness of the fan motor structure and increase its power density. This article adopts 3-D finite element analysis for electromagnetic and fluid field simulation. Moreover, a new metal 3-D printing method with a low core loss feature during high frequency operation is applied. Finally, the experimental results with a prototype are presented to verify the designed performance. [ABSTRACT FROM AUTHOR]

This article presents a method for the computation of the incremental inductances in a 12/10 variable flux reluctance machine (VFRM) using the hybrid analytical modeling coupled with a fixed-point nonlinear solver. The variation of incremental and apparent inductance with respect to the dc-field excitation is investigated for both zero and non-zero ac-field excitations. The results show that the difference between both inductance values is not negligible after 25 A/mm2 dc-current density for the investigated benchmark without the ac field. Moreover, when a non-zero ac field is introduced in addition to the dc-field, the apparent inductance becomes misleading not only under magnetic saturation but also under low excitation in the linear region of the saturation curve. The results obtained with the proposed nonlinear hybrid model are compared with the finite element method in terms of magnetic flux density distribution and incremental inductance value. The root-mean-square discrepancy of magnetic flux density distribution is found to be 37.6 mT. Furthermore, the discrepancy between incremental inductance results of the proposed method and the finite element model is calculated as 1.43%, while the proposed approach requires less post-processing and necessitates ten times less number of degrees-of-freedom. [ABSTRACT FROM AUTHOR]

This article proposes a novel two-phase dc-biased current Vernier reluctance machine (DCBVRM) equipped with concentrated windings. Compared with the existing three-phase DCBVRMs, the number of power electronic switching devices has been greatly reduced without sacrificing performance. Consequently, the overall system cost is greatly reduced, and thus, it is competitive for low-cost applications such as household appliances. To highlight the advantages of the proposed topology, the theories of coil connection, current configuration, and so on are illustrated, and some electromagnetic characteristics, such as flux density, back electromotive force, and electromagnetic torque, are predicted by finite-element analysis (FEA) with two eight-stator slot machines. Finally, the comparison with three-phase counterpart shows that the proposed eight stator slots, seven rotor slots, and two-phase machine can exhibit 21% higher torque with much lower inverter cost. [ABSTRACT FROM AUTHOR]

This article proposes new dual-stator field modulation machines with multiple magnetic excitations (MME-DSFMMs), i.e., NdFeB magnet excitation for rotor, ferrite magnet excitation for outer stator, and direct current (dc) excitation for inner stator. The open-slot stator teeth performs the role of modulator to modulate the magnetic field excited by NdFeB magnets. DC field windings with dc in the same direction are used to regulate the magnetic field. The ferrite magnets embedded at the top of outer stator slot are used to suppress the harmonic distortion. Therefore, the proposed machines have the merits of high torque production at low speed, wide speed range, and low torque ripple in full operation range. The configuration, operation principle, and design consideration of the proposed MME-DSFMMs are described. The electromagnetic performances of new topologies with different number of ferrite magnets, including back-electromagnetic force, torque characteristics, and power factor, are analyzed using finite-element analysis to show the merits of the proposed machines. [ABSTRACT FROM AUTHOR]

This article presents the simultaneous magnetic and structural topology optimization of a transverse laminated synchronous reluctance machine rotor using a solid isotropic with material penalization (SIMP)-based approach with the globally convergent method of moving asymptotes (GCMMA) optimization algorithm. Magneto-structural single and multi-objective optimization formulations are presented. The single objective formulation maximizes the average torque subject to constraints on torque ripple, Von Mises stress, and compliance. The multiobjective formulation simultaneously maximizes average torque and minimizes compliance subject to constraints on torque ripple and Von Mises stress. In both optimization formulations, the electrical steel densities in the rotor mesh elements are the control variables. Including stress and compliance in the optimization formulation ensures a structurally feasible design. The design-dependent centripetal force contributed by each element in the rotor mesh is considered dependent on its density and mass. An intermediate density material issue is observed where the density of the material in a mesh element does not converge fully to air or electrical steel. This issue is addressed through the use of a thresholding mass function which forces the convergence of the mass but not the density. The two optimization formulations are compared for rotors operating at 4000 and 12 000 r/min. An initial magnetic only topology optimization is used to seed the magneto-structural topology optimization to decrease the computational time. The impact of the magnetic only seed and rotor mesh density on the optimization outcomes is also examined. [ABSTRACT FROM AUTHOR]

We investigate the effect of magneto-mechanical and magnetocrystalline anisotropies in a test application by coupling a multiscale magneto-mechanical model with a finite element method. This first application is composed of a cylindrical conductor surrounded by a ring composed of a non-oriented FeSi3% steel sheet which contains 396 representative grain orientations. Such an application can reveal the anisotropy due to the texture of the material by inducing a rotational flux density within the ring. Moreover, the effect of the texture and the magneto-mechanical characteristic of the steel sheets is analyzed in an axially laminated synchronous reluctance machine. The effect of stress strongly emphasizes the anisotropic behavior of NO steel sheets. [ABSTRACT FROM AUTHOR]

The growth of electric and hybrid electric vehicles has drawn more attention toward the development of high power density electrical machines. The materials used in the fabrication of electrical machines play a crucial role in enhancing their power density. In this paper, the significance of advanced magnetic materials for lamination, nano-material based conducting materials, and high energy product permanent magnets (PMs) is discussed in detail. Finally, a case study has been presented with a 5 kW PM synchronous machine in order to understand the advantages of the discussed materials. [ABSTRACT FROM AUTHOR]

This article aims at investigating the impact of harmonic current, vibration, and noise on induction motors (IMs) with a fractional order (FO) proportional-integral-derivative (PID) controller. Conventional PID controllers are widely used in closed-loop vector-space to control IMs. In general, the parameters of a PID controller should be considered carefully because the vector-space loop can induce imbalanced current and magnetic flux in the $\alpha $ – $\beta $ sub-plane closed-loop system. If this occurs, the imbalanced current affects not only the IM performance but also the harmonic current, motor vibration, and noise. In this study, an FO PID ($P^{\rho }I^{\lambda }D^{\mu }$) controller is used for stabilizing the effect of the current and harmonic on the IM. This PID controller is built based on the results of measurements on motor design parameters. By using the phase margin rule to design and determine suitable parameters, several orders of $\rho $ , $\lambda $ , and $\mu $ in their reasonable ranges are evaluated to obtain a relative optimal FO ($P^{\rho }I^{\lambda }D^{\mu }$) controller. This can improve the performance of the IM in terms of harmonic current, vibration, and noise, more than a conventional PID controller can achieve. [ABSTRACT FROM AUTHOR]

This paper presents a novel magnetic bearing switched reluctance motor (SRM) (MBSRM) with two degrees of freedom suspension, consisting of an SRM and an active magnetic bearing (AMB). In the proposed MBSRM, three-phase armature windings of the SRM and a biased winding of the AMB are fed together by a modified asymmetric half-bridge converter. The rotational torque in SRM and the biased flux used for producing electromagnetic force in AMB are generated simultaneously when the MBSRM works on the traditional switched reluctance excitation mode. First, the structure and working principle of the MBSRM were introduced. Second, its theoretical formulas of suspending forces were given and validated with the finite element analysis. Third, the proposed half-bridge converter is shown, and currents in the biased winding and three-phase armature windings of MBSRM are obtained by the magnetic field–circuit coupling simulation. Moreover, a prototype is manufactured and the experiment results have proved the feasibility of the proposed converter. [ABSTRACT FROM AUTHOR]