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The use of segmented stator and rotor designs in AC electric machine construction offers several significant advantages, including a high-copper fill factor, increased torque density, improved field-weakening performance, simplified manufacturing processes, and enhanced mechanical strength. Additionally, segmented designs allow for the incorporation of oriented steel—either partially or fully—which exhibits excellent magnetic properties in the rolling direction, resulting in more efficient machine performance. However, lamination segmentation also introduces challenges. Parasitic air gaps between segments and an increased number of cut edges in the assembled stack can alter the magnetic properties of the machine, potentially leading to degraded performance. Furthermore, the use of oriented steel remains complex, as its highly nonlinear magnetic properties vary depending on the direction of the magnetic flux. This paper reviews the widely adopted stator and rotor segmentation techniques available in the literature, discussing their potential benefits and limitations. It also covers key aspects such as popular manufacturing approaches, the impact of segmentation on machine performance, advanced finite-element analysis (FEA) techniques for numerical modeling, and experimental methods for evaluating the performance of segmented stator and rotor constructions in AC machines. By addressing these areas, this work provides a comprehensive resource for machine designers seeking to develop AC machines with segmented stators and rotors. [ABSTRACT FROM AUTHOR]

Switched reluctance machines (SRMs) are potential candidates for use in the propulsion systems of electric vehicles. However, they suffer from low power density and high torque ripple. In this paper, a segmented rotor double-sided axial flux SRM (DSAFSRM) is chosen for detailed analysis. A hybrid design algorithm is proposed to take the effects of iron non-linearity into account. The proposed design procedure benefits from simplicity and high accuracy at the same time. A two-step optimization procedure is presented which minimizes the torque ripple of the DSAFSRM without jeopardizing its efficiency. The torque ripple is reduced from 120% to 35% after optimization. In the two-step optimization procedure, both geometrical and switching related parameters are investigated. Moreover, a double-sided radial flux SRM is designed and compared with the proposed DSAFSRM in terms of torque ripple, average torque, efficiency and power density. The results indicate superior performance of the optimized DSAFSRM, especially in terms of average torque, which is 26% higher than the torque produced by the double-sided radial flux SRM. [ABSTRACT FROM AUTHOR]

Switched reluctance machines (SRMs) are potential candidates for use in the propulsion systems of electric vehicles. However, they suffer from low power density and high torque ripple. In this paper, a segmented rotor double-sided axial flux SRM (DSAFSRM) is chosen for detailed analysis. A hybrid design algorithm is proposed to take the effects of iron non-linearity into account. The proposed design procedure benefits from simplicity and high accuracy at the same time. A two-step optimization procedure is presented which minimizes the torque ripple of the DSAFSRM without jeopardizing its efficiency. The torque ripple is reduced from 120% to 35% after optimization. In the two-step optimization procedure, both geometrical and switching related parameters are investigated. Moreover, a double-sided radial flux SRM is designed and compared with the proposed DSAFSRM in terms of torque ripple, average torque, efficiency and power density. The results indicate superior performance of the optimized DSAFSRM, especially in terms of average torque, which is 26% higher than the torque produced by the double-sided radial flux SRM.

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

A novel bearingless segmented switched reluctance motor (BSSRM) is proposed in this paper to solve the coupling problem of the traditional bearingless switched reluctance motor (BSRM). Different from traditional BSRMs, the proposed BSSRM adopts the double stator and segmented rotor structure, thereby making the motor operate in short flux paths and the magnetic flux path isolated between torque and suspension system. On the basis of introducing the structure and working principle of the BSSRM, the mathematical model of torque and suspension force is deduced. The 2D finite element simulation model is established by the Ansoft software. The influence of structural parameters on torque and suspension system is analyzed, and its electromagnetic characteristic and decoupling characteristic are analyzed. Compared with the double stator bearingless switched reluctance motor (DSBSRM), the BSSRM not only improves the torque and suspension output but also weakens the coupling between torque and suspension system. Finally, the simulation results verify the effectiveness of the BSSRM.

Outer-rotor switched reluctance machines (SRMs) have drawn much attention as promising candidates for in-wheel direct-drive motors of future electric vehicles. This article presents a systematic performance comparison of three outer-rotor SRM topologies for in-wheel traction applications in terms of the specific torque, electromagnetic efficiency, torque ripple, radial force, and mechanical aspects. A generalized design optimization framework for SRMs is proposed to enable the fast evaluation of large numbers of designs generated from the differential evolution by incorporating an analytical current profile estimation into the transient finite element analysis. The relationship between the saliency ratio and converter volt-ampere rating is also discussed. The calculations are then benchmarked with the experimental results from an existing prototype. The effectiveness of the performance prediction method and the proposed optimization approach is validated. [ABSTRACT FROM AUTHOR]

Field excited flux‐switching machines (FEFSMs) falls into advance category of synchronous machine. However, most FEFSM structures are comprised of overlapped stator windings, which ends up in taking more space, more copper losses and material costs. Moreover, FSM works on flux‐switching principle which made the implementation of field‐oriented control (FOC) significantly complex. This study proposes a new structure of single phase FEFSM having segmented rotor and non‐overlapped windings for the elimination of above‐mentioned drawbacks. Additionally, this study also presents a mechanism to implement FOC without the need of magnetomotive force (MMF) in the rotor. Design of this new topology and its performance characteristics have been analysed through two‐dimensional finite element analysis. FOC algorithm has been designed on the basis of sinusoidal variation of stator flux linkage due to rotor position. Experimental results show staggering performance efficiency of about 96% in terms of torque generation when compared to simulation results. Thus, verified the successful implementation of the proposed algorithm on the designed prototype. [ABSTRACT FROM AUTHOR]

In this paper, a new structure of permanent magnet axial flux-switching machine with segmented rotor has been introduced. The 12-pole stator has been installed between two 8-pole segmented rotors, and the excitation system has been connected to the rotor. This topology enhances the design of flux-switching permanent magnet machines. With this new topology, an increase in the torque density, the reduction the total harmonic distortion, simple construction, and the reduction of cogging torque have been achieved. The harmonic spectrum of the back electromagnetic force has also been improved. This topology provides an optimum power for the electric vehicles because of the short axial length and the high power density along with the low vibration and noise due to lower torque ripple and cogging torque. The three-dimensional time-stepping finite-element analysis is used to determine the flux linkage, back electromagnetic force, the output torque, and the cogging torque. A comparative analysis is made of the proposed topology and related topology in the literature. [ABSTRACT FROM AUTHOR]

Modular switched reluctance motors (MSRMs) normally have better characteristics than conventional SRMs (CSRMs) such as lower cost, higher torque production, stronger fault-tolerance, less loss, etc. This paper comprehensively investigates two hybrid-flux MSRMs with the same E-core stator, but different rotor configurations, termed as segmented-rotor MSRM (SR-MSRM) and nonsegmented rotor MSRM (NSR-MSRM), as well as compares with a CSRM. To evaluate the effects of different rotor topologies, the electromagnetic performances of two MSRMs and a CSRM with the same basic dimensions, including machine cost, flux distribution, static flux linkage, and torque, dynamic and transient operation performances are comprehensively analyzed and compared. The results based on finite-element analysis and Simulink indicate that the SR-MSRM has lowest steel consumption, highest torque production, highest power and torque densities, and strongest starting capability. Finally, three motor prototypes, including one SR-MSRM, one NSR-MSRM, and one CSRM are manufactured. The experimental results of static magnetic characteristics, dynamic and transient performances of three SRM drives confirm the predictions. [ABSTRACT FROM AUTHOR]

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]

Most of the electrical machines designed to have their stators on the outside and their rotors on the inside. However, it was noticed that the shaft fills a relatively high volume inside the machine without producing any torque. That means there is a wasted volume within the machine and this volume does not produce any torque. From this point of view, there are some trends in designing and building electrical machines to have their rotors outside the machine and their stators inside the machine. Here the example used for the machines using those designs is the permanent magnet (PM) machine, which is an electrical machines designed by the two different methods, inner and outer rotors to be used in many applications such as wind turbines and electric vehicle wheel motors. This paper is dedicated to prove that the external rotor permanent magnet machine is preferred for some significant reasons. The paper uses two approaches to demonstrate that. The first approach is using the geometrical volume of each machine to compare the torque capabilities in case of two possible topologies of the PM machines. The second approach is to compare the PM machine with another type of electrical machine, that has the same magnetic circuit topology and the rotor can be inside and outside as well. [ABSTRACT FROM AUTHOR]

Abstract: Hysteresis motors being capable of producing a steady torque at low speeds and providing good starting properties at loaded condition became popular among different fractional horse power electrical motors. High temperature superconducting materials being intrinsically hysteretic are suitable for this type of motor. In the present work, performance study of a 2-pole, 50 Hz HTS hysteresis motor with conventional stator and HTS rotor has been carried out numerically using finite element method. The simulation results confirm the ability of the segmented HTS rotor with glued circular sectors to trap the magnetic field as high as possible compared to the ferromagnetic rotor. Also the magnetization loops in the HTS hysteresis motor are obtained and the corresponding torque and AC losses are calculated. The motor torque thus obtained is linearly proportional to the current which is the common feature of any hysteresis motor. Calculations of torques, current densities etc are done using MATLAB program developed in-house and validated using COMSOL Multiphysics software. The simulation result shows reasonable agreement with the published results. [Copyright &y& Elsevier]