Electrical Machines
Seyede Delaram Sadr; Hamid Reza Izadfar
Abstract
Background and Objectives:Linear Synchronous Motors (LSMs) provide high precision, fast response, and reduced mechanical complexity, making them attractive for applications such as transportation, automation, robotics, and medical systems. Although numerous studies have investigated their structures, ...
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Background and Objectives:Linear Synchronous Motors (LSMs) provide high precision, fast response, and reduced mechanical complexity, making them attractive for applications such as transportation, automation, robotics, and medical systems. Although numerous studies have investigated their structures, modeling, and optimization, challenges such as end effects, thermal management, and cost reduction remain unresolved. This review aims to synthesize recent advancements and highlight future directions for LSM design and optimization.Methods: The study systematically reviews 54 high-quality research papers covering structural configurations, electromagnetic and thermal modeling approaches, optimization techniques, and application domains of LSMs. Comparative analysis includes flat, tubular, coreless, and superconducting designs, along with analytical, magnetic equivalent circuit (MEC), and finite element method (FEM) modeling. Multi-objective optimization strategies, intelligent algorithms, and material innovations such as Halbach arrays and grain-oriented steels are also examined.Results: Recent research demonstrates that transverse flux and tubular structures enhance thrust density by 20–35% and up to 25%, respectively, while coreless and superconducting designs reduce cogging and enable threefold thrust improvements. Advanced FEM-based multiphysics modeling provides accurate prediction of coupled electromagnetic, thermal, and mechanical behavior. Optimization strategies based on evolutionary algorithms achieved up to 12.5% thrust improvement, 8.7% loss reduction, and significant thermal enhancements through innovative cooling designs. Conclusion: LSMs are advancing through structural innovations and intelligent optimization. Despite recent progress, challenges such as cooling, scalability, and material costs persist. Future developments will rely on adaptive control, machine-learning- based design, and novel materials, strengthening the role of LSMs in industry and emerging technologies.
Electrical Machines
Alireza Shams; Esmaeel Rokrok; Behrooz Rezaeealam; Abbas-Ali Zamani
Abstract
Background and Objectives: Interior permanent magnet synchronous machines (IPMSMs) have gained increasing attention in electric vehicle applications due to their high power density, desirable efficiency, and capability of delivering maximum torque over a wide speed range. Despite these advantages, challenges ...
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Background and Objectives: Interior permanent magnet synchronous machines (IPMSMs) have gained increasing attention in electric vehicle applications due to their high power density, desirable efficiency, and capability of delivering maximum torque over a wide speed range. Despite these advantages, challenges such as torque ripple and suboptimal efficiency remain. This study aims to propose a design and multi-objective optimization approach for Stator-Optimized Delta-Type IPMSM (SO-DT-IPMSM) motor to enhance efficiency, reduce torque ripple, and improve average torque. Methods: A multi-objective particle swarm optimization (MOPSO) was employed to determine the optimal set of stator parameters. In this study, an existing delta-type IPMSM rotor topology was adopted and all rotor parameters were kept fixed, while the optimization was exclusively performed on stator geometry. Electromagnetic modeling and performance evaluation of the proposed design were carried out using Ansys Electronics. Following the optimization process, a prototype motor was manufactured and assembled based on the optimized design parameters, and experimental tests were conducted to validate the simulation results. Results: Simulation results revealed significant improvements in the SO-DT-IPMSM compared with the Nissan Leaf IPMSM motor (Initial IPMSM). The optimized design achieved a 21% increase in average torque, 40% reduction in torque ripple, and 5% improvement in overall efficiency. Experimental tests performed on the fabricated prototype confirmed the accuracy of the simulation findings and demonstrated strong agreement between analytical and experimental data.Conclusion: The proposed design and optimization approach effectively enhanced torque, torque ripple, and efficiency in the IPMSM. Beyond the validated experimental performance, the results demonstrate that the presented methodology can serve as a practical solution for improving electric vehicle motor performance. Moreover, the introduced optimization framework has the potential to be extended to other motor topologies and applications.
Electrical Machines
Seyed Reza Mousavi-aghdam; Seyed Abbas Azimi; Farzad Sedaghati
Abstract
Background and Objectives: Synchronous reluctance motors (SynRMs) have considered as energy-efficient alternatives to conventional induction motors (IMs), primarily due to high efficiency. Despite their low losses, SynRMs are hindered by inadequate line-start capability and a low power factor, which ...
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Background and Objectives: Synchronous reluctance motors (SynRMs) have considered as energy-efficient alternatives to conventional induction motors (IMs), primarily due to high efficiency. Despite their low losses, SynRMs are hindered by inadequate line-start capability and a low power factor, which restrict their use in industrial settings. This article addresses these limitations by introducing a line-start permanent magnet-assisted SynRM (LS-PMaSynRM) that incorporates fluid-type flux barriers. This design aims to enhance starting performance and increasing power factor.Methods: The design process entailed a parametric sensitivity analysis of critical motor characteristics, including rotor geometry, stator winding configuration, and stator slot count. Finite Element Method (FEM) simulations were executed using time-stepping analysis to assess the motor's electromagnetic behavior under both transient and steady-state conditions. Performance metrics such as torque ripple, average torque, efficiency, and power factor were evaluated. Comparative simulations with conventional SynRM and PMaSynRM designs were also conducted to benchmark improvements.Results: The proposed LS-PMaSynRM exhibited substantial enhancements in line-start capability, achieving stable synchronization within a brief period. The motor demonstrated a significant increase in power factor relative to conventional SynRM designs, while maintaining high efficiency throughout the operating range.Conclusion: The study presents an LS-PMaSynRM architecture that effectively addresses traditional limitations in line-start performance and power factor. These findings support the broader industrial adoption of SynRMs and offer a practical design pathway for future high-efficiency motor applications.
Electrical Machines
Pouria Nadri; Behrooz Rezaeealam; Morteza Mikhak-Beyranvand
Abstract
Background and Objectives: Dual-rotor synchronous motors with counter-rotation are of significant interest for electric machine design due to their high performance and specific applications. In this study, a new Counter-Rotating Dual-Rotor Synchronous Motor (CRDRSM) is presented, with the permanent ...
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Background and Objectives: Dual-rotor synchronous motors with counter-rotation are of significant interest for electric machine design due to their high performance and specific applications. In this study, a new Counter-Rotating Dual-Rotor Synchronous Motor (CRDRSM) is presented, with the permanent magnet (PM) rotor as the outer rotor and the reluctance rotor as the inner rotor.Methods: To identify the optimal structure, the effects of distributed and fractional-pitch windings are first compared. Then, various PM and reluctance rotor topologies are examined in order to select the optimal combination. Despite high output torque, cogging torque significantly affects motor performance; therefore, reducing cogging torque is the main concern of this research. Dimensional optimization is conducted using the Taguchi method to minimize cogging torque in the PM rotor. Four key design parameters, including the PM arc, PM thickness, stator opening slot, and stator tooth width, are selected as optimization variables, while other parameters are kept constant. The minimum and maximum ranges of these variables are determined using parametric scanning and ANSYS Maxwell finite element software. Briefly, the optimization process proceeds in three stages: (1) winding configuration comparison, (2) selection of optimal inner and outer rotor structures, and (3) dimensional optimization using the Taguchi method.Results: Analysis of the results demonstrates that the cogging torque of the proposed motor is reduced by up to 62.36%, the output power and efficiency are increased, and the voltage THD is also reduced. Other performance characteristics, including output torque and electromagnetic stability, are improved compared to the initial design or remain at a desirable level.Conclusion: Finite Element Analysis (FEA) demonstrated that the distributed winding configuration delivers the best performance among all tested options. Model C, featuring a hyperbolic-line reluctance inner rotor combined with a surface-mounted PM outer rotor, was identified as the best configuration. This model offers an excellent balance of high torque, low torque ripple, minimized back-EMF harmonics, and satisfactory efficiency, making it highly suitable for submarine propulsion systems. To further reduce cogging torque (one of the primary sources of torque ripple and acoustic noise), the motor geometry was optimized using the Taguchi method and FEA. Overall, the electromagnetic performance of the proposed CRDRSM was validated in terms of flux density distribution, output torque, and cogging torque.
Electrical Machines
H. Afsharirad; S. Misaghi
Abstract
Background and Objectives: Due to the high torque ripple and stator current harmonics in direct torque control using a two-level inverter, the use of multi-level inverters has become common to reduce these two factors. Among the multilevel inverters, the Neutral-point-Clamped Inverter has been given ...
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Background and Objectives: Due to the high torque ripple and stator current harmonics in direct torque control using a two-level inverter, the use of multi-level inverters has become common to reduce these two factors. Among the multilevel inverters, the Neutral-point-Clamped Inverter has been given more attention in the industry due to its advantages. This inverter has 27 voltage vectors by which torque and flux are controlled. In order to reduce torque ripple and current harmonic as much as possible, methods such as space vector modulation methods or the use of multi-level inverters with higher levels have been considered. But the main drawback of these methods is the increase of complexity and cost.Methods: In this article, virtual voltage vectors are used to increase the number of hysteresis controller levels. These vectors are obtained from the sum of two voltage vectors. In this way, we will have 12 voltage vectors in addition to the diode clamped inverter’s voltage vectors. Therefore, we can increase the number of torque hysteresis levels from 7 levels to 11 levels.Results: Considering that the proposed method uses virtual vectors and voltage vectors, it does not increase the cost and computational complexity. Also, one of the requirements of using this method is the use of fixed switching frequency, which solves the variable switching frequency problem of conventional methods. Therefore, the proposed control reaches an overall optimization.Conclusion: To verify the feasibility of the proposed method and compare it with the conventional method, both of these methods are simulated in the MATLAB /Simulink environment and the simulation results represent the efficiency of the proposed control method. This method achieves less torque ripple and harmonic current without increasing the cost and computational complexity.
Electrical Machines
R. Rouhani; S.E. Abdollahi; A. Gholamian
Abstract
Background and Objectives: The rotor of synchronous reluctance machines (SynRM) is conventionally designed and implemented in two types of axially-laminated anisotropic (ALA) and transversely-laminated anisotropic (TLA). Torque ripple and power factor have always been the design challenges of this machine; ...
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Background and Objectives: The rotor of synchronous reluctance machines (SynRM) is conventionally designed and implemented in two types of axially-laminated anisotropic (ALA) and transversely-laminated anisotropic (TLA). Torque ripple and power factor have always been the design challenges of this machine; however, with proper design, their values can be as close as possible to the desired value. Each of these two structures has some advantages over the other, in terms of electromagnetic performance and ease of construction. For the first time, in this paper, a hybrid anisotropic rotor is presented with both radial and axial laminations, Based on the theory of anisotropic rotor structure for the fundamental harmonic and isotropic rotor structure for other harmonics, so that the designed motor meets the advantages of both structures as much as possible.Methods: To this end, the proposed design is implemented and investigated a Magnetic Equivalent Circuit(MEC) for the first slot harmonic on a machine with stator of 24-slots. To evaluate the proposed design, its electromagnetic performance is simulated using Finite Element Method.Results: The theory-based conceptual design method is applied to a rotor with new structure and simulation results including average torque, power factor and torque ripple of the machine are presented.Conclusion: Based on the obtained simulation results and comparing performance of the proposed design with other structures, it is shown that there will be a significant improvement in electromagnetic features including torque ripple, average torque and power factor and the proposed design has lower torque ripple than ALA rotor and higher average torque and power factor than TLA rotor.
Electrical Machines
S. Nasr; B. Ganji; M. Moallem
Abstract
Background and Objectives: Due to exclusive advantages of the permanent magnet synchronous motors (PMSMs) such as large torque/power density, high efficiency and wide speed range in constant power region, special attention has been paid to these motors especially for electric vehicle (EV) application. ...
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Background and Objectives: Due to exclusive advantages of the permanent magnet synchronous motors (PMSMs) such as large torque/power density, high efficiency and wide speed range in constant power region, special attention has been paid to these motors especially for electric vehicle (EV) application. A conventional type of PMSMs which is more suitable for EV application is the interior permanent magnet synchronous motors (IPMSM). The main objective of the present paper is design optimization of this type of PMSM to increase efficiency and reduce torque ripple which are important for EV application. Methods: Using different shape design optimization methods including rotor notch, flux barrier and skewed rotor, design optimization of the delta-shape IPMSM is done and an optimized design is suggested first. One of the most important factors affecting the performance of the IPMSM is the magnet arrangement in the rotor structure. Based on the the design of experiments (DOE) algorithm, optimal values of some design parameters related to magnet are then determined to improve more the motor performance of the suggested structure.Results: The simulation results based on finite element method (FEM) are provided for a typical high-power IPMSM to evaluate the effectiveness of the proposed technique. In comparison to the initial design, 7% increase of average torque, 50% reduction of torque ripple and 1.4% increase of efficiency are resulted for the optimized motor. Conclusion: Using the proposed hybrid design optimization procedure (shape design optimization with optimum design parameters), significant improvement of some characteristics related to the delta-shape IPMSM including efficiency, average torque and torque ripple is resulted and this conclusion is desirable for EV application.
Electrical Machines
S. Niknafs; A. Shiri; S. Bagheri
Abstract
Background and Objectives: In recent years, linear generators have been broadly utilized to harness wave motion energy. There are various types of linear generators with different magnetic and geometric structures. Among these generators, linear permanent magnet synchronous generator provides a higher ...
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Background and Objectives: In recent years, linear generators have been broadly utilized to harness wave motion energy. There are various types of linear generators with different magnetic and geometric structures. Among these generators, linear permanent magnet synchronous generator provides a higher energy density than other generators. Due to the simplicity of the structure and the low cost of producing a flat double-sided structure, this type of structure is investigated in this paper.Methods: The purpose of the paper can be divided into two main categories: first, modeling of the flat double-sided linear permanent magnet synchronous generator by using magnetic equivalent circuit (MEC) method and second, deriving the generator electrical equations which are used in analysis and design process.Results: The behavior of the linear permanent magnet synchronous generator is studied and the induced voltages are calculated. The no-load and loaded conditions of the generator with different loads are investigated and the voltage and the current of the load are obtained. Conclusion: In order to confirm the results, finite element method (FEM) is employed. The designed linear generator is simulated by FEM. Comparing the results obtained by MEC and FEM show good agreements between two methods, validating the presented modelling method.
