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- ItemInvestigation of Different Pole Configurations in New Asymmetric Permanent Magnet Synchronous Reluctance Machines(New York, NY : IEEE, 2025-01-13) Ajamloo, Akbar Mohammadi; Ghaheri, Aghil; Ibrahim, Mohamed N.; Sergeant, PeterThis paper investigates the impact of pole number and configuration on key performance characteristics of a new family of asymmetric permanent magnet synchronous reluctance machines (PMSynRMs). New variants of asymmetric PMSynRMs are presented here which integrate distinct interior PM (IPM) poles and reluctance poles into a single lamination. The torque enhancement principle relies on segregating the net torque into components generated by each pole type. Torque enhancement is achieved by optimally shifting the IPM poles relative to the reluctance poles, aligning the torque peaks generated by each pole type. A comprehensive comparative analysis is conducted between the proposed asymmetric and conventional topologies, with identical PM volume, copper loss, frequency, and frame size. The analysis evaluates torque production capability, unbalanced magnetic forces, torque ripple, losses, and power factor. The results reveal that the asymmetric PMSynRMs offer improved torque, power factor, and reduced torque ripple compared to conventional designs for pole numbers 4, 6, 8, and 10. However, some asymmetric designs exhibit the drawback of unbalanced magnetic forces, which should be taken into consideration. Finally, an asymmetric PMSynRM is prototyped and tested to verify the simulation results.
- ItemProperties of Additively Manufactured Soft and Hard Magnetic Cores for Electrical Machines: Methods and Materials − A Review(New York, NY : IEEE, 2025-05-20) Ajamloo, Akbar Mohammadi; Ibrahim, Mohamed N.; Sergeant, PeterAdditive Manufacturing (AM) is an emerging topic in the field of electrical machines (EMs), offering the potential to overcome challenges imposed by conventional manufacturing methods. This paper provides an overview of various AM methods and materials used to manufacture soft and hard magnetic cores for EMs, with a particular focus on their multiphysics properties. Since each AM method involves unique processes—such as particle bonding, melting, or sintering—the resulting microstructural properties of the printed cores differ, leading to varied multi-physics characteristics that require indepth study. The paper outlines both the benefits and challenges associated with AM techniques and materials. Importantly, it explores the detailed properties of Fe-Si and Fe-Co soft magnetic cores as well as hard magnetic cores including NdFeB, ferrite, and alnico printed through different AM methods, comparing them to traditional laminations and commercial hard magnets.
- ItemPrinciple of Torque-Axis Alignment in New Asymmetric PM Synchronous Reluctance Machines: Toward Less-Rare-Earth PM Machines(Piscataway, NJ : IEEE, 2024-12-05) Ajamloo, Akbar Mohammadi; Ghaheri, Aghil; Ibrahim, Mohamed N.; Sergeant, PeterThis article reveals the principle of a new torque-axis alignment technique as the basis for a new class of asymmetric permanent magnet synchronous reluctance machines (PMSynRMs). These machines are characterized by having distinct permanent magnet (PM) and SynRM poles. The objective is to precisely align peak torque from each pole type by adjusting the relative shift angle, minimizing the rare-Earth PM usage. A new analytical model is proposed, segregating torque generated by each pole type in a rotating dq reference frame. The impact of PM pole configuration—surface PM (SPM) and interior PM (IPM)—is examined, and the effects of cross-coupling and saturation are investigated. Two different torque separation models are used to describe key torque characteristics of the machines. The analysis indicates that the asymmetric IPMSynRM and SPMSynRM offer the same torque rating at a significantly lower PM volume usage compared with the conventional PM-assisted synchronous reluctance machine (PMaSynRM). In addition, it is observed that asymmetric IPMSynRM exhibits superior torque performance compared with asymmetric SPMSynRM, attributed to additional reluctance torque generated by IPM poles. Finally, a prototype is manufactured and tested to evaluate the presented principle in the asymmetric topologies.
- ItemOptimisation of Additively Manufactured Hairpin Windings for High Power Density Traction Motors(Piscataway, NJ : IEEE, 2025-07-04) Tesfamikael, Hadish Habte; Notari, Riccardo; Murataliyev, Mukhammed; Wang, Meiqi; Gerada, Chris; Degano, MicheleDespite the widespread use of hairpin winding (HW) in electric vehicle (EV) traction motors, several AC loss phenomena hinder its broader application at higher operating frequencies. This paper investigates methods for reducing AC copper losses, focusing on both design approaches and advanced manufacturing techniques, particularly additive manufacturing (AM). A comprehensive analysis of various HW layouts is conducted, evaluating AC copper losses through finite element (FE) and analytical approaches, while considering the effects of circulating currents and short pitching. Detailed analysis of a HW motor is performed to address the influence of magnetic saturation and rotor-magnetomotive force (MMF) on AC copper losses. Moreover, sizing of HW dimensions at a specific operating speed is carried out analytically and validated using FE analysis, with the aim of minimizing high-frequency losses. The potential of AM to enhance manufacturing flexibility and facilitate conductor size optimization is briefly explored. A case study with in-depth optimization is performed to determine the optimal HW dimensions at representative operating points along the torque-speed curve. As a result, the most suitable HW design for EV applications is proposed and benchmarked against results from rigorous optimization processes.
- ItemA Review on Properties of 3D Printed Magnetic Cores for Electrical Machines: Additive Manufacturing Methods and Materials(Piscataway, NJ : IEEE, 2024-10-09) Ajamloo, Akbar Mohammadi; Ibrahim, Mohamed N.; Sergeant, PeterAdditive Manufacturing (AM) is a new topic in the field of electrical machines (EMs), offering the potential to overcome the limitations in the design of EMs. Through AM, complex 3D geometries and the utilization of Fe-Si cores with 6.5% silicon can be achieved, leading to enhanced EM performance without concerns about manufacturing cost and complexity. This paper provides an overview of various AM methods and materials used in manufacturing soft magnetic cores for EMs, with a particular emphasis on the multi-physics properties of these cores. Due to the distinct fusion processes in each AM method, the microstructural properties of the printed cores vary, leading to diverse multi-physics properties that require detailed investigation. The paper outlines both the benefits and challenges associated with AM techniques and materials. Importantly, it explores the detailed characteristics of Fe-Si and Fe-Co cores manufactured through different AM methods, comparing them with commercial laminations such as 35A300, JNEX Super Core, and Hiperco 50A.