The impedance swing of a power transformer, defined as the variation of impedance with tap position, critically influences fault levels, losses, and overall design efficiency. Deviations from the target impedance range increase short-circuit currents or elevate stray and eddy losses, leading to higher material usage, thermal stress, and cooling requirements. Thus, effective control of impedance swing is essential for cost-optimal and reliable transformer design. This paper introduces the impedance swing rate as a key performance metric, defined as the normalized peak-to-peak variation of impedance across the full tap range, calculated as the difference between the maximum and minimum impedance divided by the nominal impedance, and presents a predictive geometric framework linking winding order to impedance variation. Using a 30-MVA power transformer with separate coarse and fine tap windings, the effects of winding spatial order on leakage field distribution are investigated through combined analytical modeling and 3-D finite-element analysis. An MMF-based analytical formulation identifies the effective inter-winding channel width as the dominant geometric factor, and the results are validated against experimental test results.

This article proposes a novel multitooth interactive flux reversal permanent magnet (IFRPM) motor. The innovative motor design incorporates both tooth and yoke PMs, providing both flux reversal (FR) and biased flux (BF) effects, respectively. The former directly contributes to torque production and an increase in air-gap flux density, while resulting in a decrease in stator-pole flux. Using flux modulation theory (FMT), the influence of each harmonic on the torque generation is analyzed. The motor’s dimensions are optimized using a genetic algorithm to achieve the maximum torque while minimizing the torque ripple. Four benchmark motors, two with FR effect and two with BF effect, are used for comparison. The findings underscore the superior performance of the IFRPM. First, the IFRPM reduces saturation levels compared to BF motors. Additionally, a torque quality factor (TQF) is introduced, which considers the average torque, torque ripple, and PM volume, providing a fair evaluation. The IFRPM achieves a 669% and 95% improvement in TQF over recent FRPMs of similar size, respectively. It offers at least a 318% higher TQF than BF motors. Furthermore, the IFRPM exhibits the lowest torque ripple in overload conditions. Finally, the motor is prototyped and experimentally validated.

In contemporary power systems, it is crucial to ensure stable voltage levels to mitigate the fluctuations resulting from diverse load conditions. On-load tap changers (OLTCs) play a pivotal role in addressing these fluctuations by dynamically adjusting the number of turns in the transformer winding. This study investigates the integration of OLTCs within transformer designs, focusing on various methodologies related to tap winding order and configurations, which are vital for both electrical and magnetic performance. A comprehensive review of the operational principles governing different types of OLTCs is provided, highlighting their significance in voltage regulation. Furthermore, this paper analyzes the impact of linear OLTC winding order on the short-circuit impedance of a 30 MVA transformer. The findings underscore the importance of OLTC selection and design in optimizing transformer performance.

In the design optimization of electrical machines, highly accurate numerical models are indispensable. However, due to their time-consuming nature, the computational efficiency of the optimization procedure is deteriorated. To get rid of the issue, developing both time-efficient and accurate finite element solvers is pivotal, by which a high number of function evaluations can be executed without the traditional concerns. This paper presents a comparative study of first- and second-order triangular finite element solvers applied to two-dimensional nonlinear magneto-static problems commonly encountered in the analysis of electrical machines. Accordingly, identifying the minimum mesh density required for first-order elements to produce acceptable results enables the efficient use of first-order meshes in large-scale optimization tasks, thereby balancing accuracy with computational efficiency. The finite element formulation is based on the magnetic vector potential, and a detailed implementation of the Newton–Raphson nonlinear solver is presented and thoroughly discussed. Three benchmark cases are considered, including a current-carrying conductor, an L-shaped ferromagnetic domain with nonlinear B(H) curve behavior, and a switched reluctance machine (SRM) featuring pronounced local magnetic saturations in its rotor and stator iron cores. Accuracy, convergence, and computational cost are assessed for both element orders on topologically equivalent meshes. The results demonstrate that while second-order elements are essential for accurately capturing local saturation effects, first-order elements can still deliver sufficiently accurate results in a computationally efficient manner, making them suitable for optimization tasks.

Synchronous reluctance motors (SynRMs) have recently gained attention as a high-efficiency alternative to induction motors (IMs) in industrial applications. While IMs are valued for their robustness and simplicity, their efficiency is limited by rotor Ohmic losses. In contrast, SynRMs employ a laminated iron rotor without windings or permanent magnets, eliminating rotor Ohmic and magnet-related losses and thereby improving efficiency, thermal performance, and reliability. However, their widespread adoption is hindered by high torque ripple resulting from rotor magnetic anisotropy and spatial harmonics produced by the stator winding. This paper presents a comparative investigation of twelve SynRM configurations obtained by combining different stator winding-layer and rotor flux-barrier-layer arrangements. Finite element method (FEM) simulations are performed to evaluate the electromagnetic performance of each design, followed by harmonic analysis of the developed torque. Among the investigated configurations, the W3L-4FB topology achieves the lowest torque ripple of approximately 11% while maintaining an average torque of about 5.1 Nm. Considering both electromagnetic performance and manufacturing simplicity, the W1L-4FB configuration is selected for prototyping. Furthermore, applying a 10° rotor skew reduces the torque ripple to below 3% with only a minor reduction in average torque. Experimental measurements closely agree with the FEM predictions, confirming the accuracy of the proposed design methodology and demonstrating an effective approach for achieving low-torque-ripple SynRMs without sacrificing practical manufacturability.

Biased flux motors are a configuration of electrical machine where the rotor is pure iron and magnets are buried in the stator yoke iron. In this paper, a biased-flux motor is proposed and validated in which the stator coreback permanent magnets are configured to a flux concentrating V-type arrangement. By switching from the more usual circumferential magnets, it has been shown that torque production per unit magnet mass can increase by over 20% for a moderate 0.5% increase in torque ripple. This is by virtue of the significant increase in flux concentration in the air gap, which is proven mathematically, via simulation and validated experimentally. It is also shown that due to the new permanent magnet shape, demagnetization is limited. A comprehensive comparison is done to show the superiority of the proposed structure. Finally, validation of the theoretical and FEM analyses has been done experimentally by a prototyped 24/25 V-type motor.

This article studies a new stator-permanent magnet (PM) motor with flux-switching (FS) and flux-reversal (FR) effects synergies. The proposed structure benefits from the splitting stator pole PMs and consequent-pole FRPM, which reduces the PM utilization compared to the conventional ones. Also, the proposed structure is optimized by a random search multiobjective algorithm to attain the structure with the highest output torque and minimum torque ripple. Additionally, the proposed motor is compared to a conventional FSPM to investigate the advantages of the main motor. Using finite element analysis (FEA) studies, the flux density distribution results show that the FR effect lowers the saturation risk compared to FSPM. Also, the back-EMF generation of the proposed motor has improved by 135% compared to its benchmark. Correspondingly, fullload results show that the proposed topology has enhanced the average torque by 75% and deteriorated the ripple by about 55% compared to FSPM. Therefore, the proposed structure offers a profitable for high torque density applications.

Due to their numerous advantages, induction motors (IMs) have garnered significant interest over the years. Addressing the critical issue of reducing energy consumption, optimizing electric motors remains a paramount concern. However, the presence of Ohmic losses in the rotor cage of IMs limits their efficiency. In recent years, several studies have explored replacing IMs in fan and pump applications with alternative electric motor types to enhance efficiency. One promising option is the linestart permanent magnet-assisted synchronous reluctance motor (LS-PMaSynRM), which can achieve IE4 and potentially the upcoming IE5 efficiency classes for the same output power compared to IMs. This work extends the authors' previous efforts in implementing LS-PMaSynRMs for fan and pump applications. The paper focuses on rotor design using three-dimensional finite element analysis (FEA) and the standard prototyping process of an LS-PMaSynRM for pump applications. A benchmark 0.75 kW 1500rpm IM is considered, with its rotor replaced by the newly designed rotor. The finite element analysis results are presented and discussed. Simulation results are further validated through experimental prototyping and testing of the case-study motor. Finally, the performance characteristics of the prototyped motor are compared with those of a counterpart IM.

This paper proposes a novel modular consequent pole flux reversal permanent magnet (CPFRM) motor, which improves air-gap flux density and enhances performance under both no-load and full-load conditions. The improvement in air gap flux is demonstrated through a simplified magnetic equivalent circuit (MEC) in comparison with a conventional flux reversal motor (FRM). Furthermore, the proposed CPFRM is optimized using a genetic algorithm (GA) to maximize average torque while minimizing torque ripple. Performance enhancements over conventional motors are analyzed using finite element analysis (FEA) under no-load, full-load, and overload conditions. FEA results validate the superiority of the proposed motor, showing a 33.3% and 7.1% increase in full-load torque compared to fluxswitching and flux-reversal PM motors, respectively. Additionally, the motor prototyping procedure is described in detail. A comprehensive conclusion summarizes the key findings.

This paper presents the design and simulation of an electric bicycle system developed in the MATLAB/Simulink environment. The proposed system integrates electrical, mechanical, and control subsystems in a modular framework, enabling detailed analysis of their interactions. A cyclist model is incorporated to realistically represent human limitations in torque and power delivery, allowing accurate assessment of rider-vehicle dynamics. The modeling procedure uses built-in Simulink components such as Vehicle Body Total Road Load, along with custom-developed blocks to capture braking behavior and cyclist contributions. To validate the system, several test scenarios were implemented, including acceleration, maximum speed analysis, hill-climbing on graded slopes, and evaluation under the JPN10 drive cycle. These outcomes highlight the modular Simulink model’s capability to provide a reliable and flexible platform for analyzing electric bicycle performance and optimizing system design.

Meta-heuristic optimization methods are popular today, but they still face many problems, such as early convergence, weak scalability, and high computing cost. As engineering problems grow larger and more complex, the need for an optimizer that can search broadly, converge quickly, and keep the computation affordable becomes even more urgent. To address these issues, this paper introduces a novel human inspired metaheuristic algorithm, the cultural history optimization algorithm (CHOA), based on cultural history principles. CHOA’s performance is evaluated against 47 benchmark functions and the CEC06−2019 test suite, encompassing large-scale unimodal, multimodal, and fixed-dimension functions. Results demonstrate CHOA’s strong exploration and exploitation capabilities, achieving global optima with rapid convergence and manageable computational cost. Performance metrics, including mean cost, standard deviation, convergence acceleration, and computational burden, are compared with established metaheuristics, highlighting effectiveness. Moreover, Wilcoxon rank-sum tests confirm CHOA’s statistical superiority. As a large-scale design optimization problem, CHOA and state-of-the-art algorithms are applied to optimize a permanent magnet synchronous motor, showcasing CHOA’s local optima avoidance and scalability. Finally, the paper describes a graphical user interface (GUI) developed for CHOA to facilitate its practical application.

PM-assisted synchronous reluctance motors (PMa-SynRMs) have recently emerged as a promising option for high-efficiency and cost-effective electric drives. This paper presents a comprehensive multi-objective treatment that includes design, electromagnetic assessment, and thermal analysis of a PMa-SynRM, employing two different magnet materials: neodymium-iron-boron (NdFeB) and ferrite. The developed machine was meticulously modelled using finite element analysis (FEA) to study back electromotive force (B-EMF), torque profile, terminal voltage, and efficiency maps for various loading conditions. Subsequently, thermal 3D simulations in ICEPAK were conducted for several representative operating points to evaluate the temperature distribution in the stator, rotor, winding, and magnets. The findings underscore the thoroughness of the study and the intricate trade-offs between cost, thermal reliability, and electromagnetic performance. These results provide valuable insights for the industrial design of sustainable electric drives, ensuring confidence in the investigation's findings.

De-energized tap changers (DETCs) offer a cost-effective means of voltage regulation in transformers with steady load conditions, serving as an alternative to on-load tap changers (OLTCs). Unlike separate DETC units, integrated DETC designs are embedded into the main winding structure, where the introduction of air gaps results in non-uniform ampere-turn distributions. This structural difference alters the impedance profile, increasing radial leakage reactance. Elevated impedance can enhance eddy current and stray losses, thereby raising overall load losses and operating temperatures, which may necessitate additional cooling provisions and impact long-term reliability. This paper investigates the impact of integrated linear and bridge DETC configurations on transformer impedance. An analytical modeling framework is proposed for both configurations, with impedance behavior evaluated to highlight performance and design implications.

This paper presents an innovative outer-stator permanent magnet (PM) motor based on the flux-switching (FS) principle. The key novelty of the proposed design lies in the use of segmented stator-pole PMs, which significantly reduces the amount of PM material required compared with conventional outer FSPM machines. To further enhance the electromagnetic performance, a genetic algorithm is employed to optimize the design, aiming to maximize torque output while minimizing torque ripple. The proposed configuration is benchmarked against a conventional outer FSPM topology to emphasize its advantages. Finite element analysis (FEA) results demonstrate that segmenting the PMs reduces torque per magnet volume by 27.3% and effectively alleviates PM saturation issues. Therefore, the proposed topology offers high suitability for applications demanding high torque density.

This article proposes a new flux reversal permanent magnet (FRPM) motor assisted with yoke and slot permanent magnets (PMs). While the tooth PMs directly affect the air-gap flux density and contribute to torque production, the yoke and slot PMs significantly assist with torque ripple mitigation, lower core saturation, and torque enhancement. A conventional FRPM is considered for comparison to explain the effectiveness of the added PMs. We use flux modulation theory (FMT) to analyze the working harmonics in both no-load and on-load conditions in torque production, back electromotive force (back EMF), and cogging torque calculation. Also, the proposed and benchmark motors have been optimized using a genetic algorithm. Finite element analysis (FEA) results are carried out to verify the accuracy of the FMT modeling. Furthermore, different PM arrangements, including slot-tooth PM (STPM), yoke-slot PM (YSPM), and yoke-tooth PM (YTPM), are simulated with FEA and compared with the proposed motor. It is shown that the auxiliary PMs increase the torque of the proposed motor by 30% compared to the existing FRPM with 75% lower torque ripple. Among the compared structures, the proposed motor offers the highest torque density and efficiency. Finally, the proposed FRPM is prototyped and tested under no-load and on-load conditions to verify the simulations.

This article proposes a new consequent-pole (CP) flux reversal permanent magnet (FRPM) motor with homopolar PMs parked in the stator slot openings and between the wound poles' teeth. The proposed PM pattern offers an effective PM usage and lowers the effective armature air-gap length while increasing the output torque. The operating principle of the motor is analysed using a flux modulation theory (FMT) and the predominant harmonics of the air-gap flux density are unveiled. Furthermore, the proposed structure is comparatively analysed with a CPFRPM and a conventional FRPM (CFRPM). These structures are optimised with a genetic algorithm, and by using the finite element analysis (FEA), the no-load and full-load performances are studied. Thanks to effective PM placement, the torque density is improved by 65% and 29% compared to the CFRPM and CPFRPM, respectively. PM demagnetisation, along with a thermal analysis, is developed to guarantee that the PMs are not prone to demagnetisation. A comparative study is also performed to highlight the outperformance of the proposed structure among the stator-PM motors. Eventually, the motor is prototyped and tested to validate the FEA predictions.

This paper introduces EMDLAB (Electrical Machines Design Laboratory), a finite element package developed in MATLAB for the electromagnetic analysis of electrical machines. The package is designed for researchers and engineers who require an open-source and flexible environment for modeling and simulation. EMDLAB includes modules for geometry creation, meshing, material modeling, boundary condition definition, solving, and post-processing. The framework is modular and scriptable, enabling automation and customization. The accuracy and performance of EMDLAB are demonstrated through benchmark examples involving switched reluctance, induction, and permanent magnet machines. Simulation results are compared with those obtained using commercial software, showing good agreement in predicted total energy and co-energy, flux linkage, torque, and flux density distributions. The package provides a transparent and reproducible tool for academic research and education. Its open-source nature encourages collaboration and facilitates easy extension of the code, making it particularly valuable for method development and academic use.

Biased-flux motors are a type of electric machine that operate in an unconventional manner but can offer structural and performance advantages over more conventional topologies. Achieving a suitable design in this relatively uncommon topology requires identifying the effect of various factors on its performance. Even small changes in the structure and magnet configuration can have a significant impact on performance. In this paper, the magnet configuration, flux barriers and bridges are investigated to try and improve the performance of a baseline biased-flux motor. The details of the structure and operating principles are explained, and structures are optimised for torque production in a fixed volume. The no-load and full-load operations of alternative variants are studied in terms of cogging torque, flux density, flux line, torque profiles and overload capability. Moreover, a complete comparison has been made between split-magnet and single-magnet topologies in an intermodular permanent magnet motor. The magnetic stresses on the PMs are studied to assess the demagnetisation risks. It has been explained how splitting the magnets and introducing flux barriers increase the torque density and flux bridges decrease the demagnetisation risk. To better analyse the PM demagnetisation, a thermal study is carried out, and the PMs' B-H curve is modified accordingly. A comparative study is also conducted with other stator-permanent magnet motors to better assess the demagnetisation behaviour of the proposed topologies.