Metal additive manufacturing (AM) has been growing remarkably in the past few years. Thanks to the advantages of unmatched flexibility and zero material waste, this clean technology opens the door for new design solutions with greater material efficiency, which are not possible through conventional machining techniques. In this paper, we provide a technology overview of metal AM techniques that can be utilized in a wide range of applications, including constructing electrical machines. Different techniques of metal AM are discussed and compared. Additionally, the impact of the material forms (powder/wire) on printing speed and quality are studied. Based on the industrial and technical literature, this paper provides a comprehensive review of metal AM in the fabrication of electrical machines and their applications. This includes the current state of the art and associated benefits of AM in these applications.

The ever-increasing demand for higher-power dense electrical machines has resulted in different electrical, mechanical, and thermal stresses, which can eventually cause machine failure. For this reason, the management of stresses and losses must be thoughtfully investigated to have a highly reliable electrical machine. The literature agrees that winding losses are the dominant loss mechanism in many electrical machines. However, statements vary on how to mitigate these losses along with the aforementioned stresses. To avoid winding failure, a study of the various winding topologies would allow for a better consideration of the challenges and limitations in the performance of different electrical machines. To this aim, this paper introduces a comprehensive review for different winding topologies. Many reported cases in the literature are summarized and compared. Moreover, the utilization of additive manufacturing (AM) in the production of the machine windings is presented, showing a high level of maturity of this emerging technology. Finally, different challenges facing the design of machine windings are introduced including the AC high frequency losses, thermal management, mechanical and acoustic problems, insulation aging, automated production, and winding manufacturability.

Nowadays, additive manufacturing (AM) is becoming a more feasible solution for scalable electric drives compared to traditional production systems. Also, with the significantly growing automotive sector, innovation in electric machine technology is evolving rapidly. With the unmatched freedom in geometry, AM offers a great deal of flexibility in the design of electrical machine parts. Not only the passive parts can be printed such as the frame and the shaft of the electrical machine, but also active parts, such as windings, can be printed in lightweight materials such as Al–Si–Mg-based alloy. The main focus of this article is to further utilize AM in the design of electrical machine windings, with low weight and low losses especially at high-frequency (HF) operation. Aiming at HF loss reduction, different AM coils are prototyped using different materials, and their performance is compared with traditionally manufactured coils. Moreover, a new design concept of shaped-profile conductors is presented with reduced proximity effect and less impact by the cross-slot leakage flux. This design combines high electromagnetic performance and ultralightweight merits, allowing for higher power density electrical machines.

In high-speed and high-frequency electric machines, one of the major issues that impacts the performance and capability of a machine is the high-frequency eddy current losses in the windings. This work deals with AC winding losses in flat rectangular conductors. Aiming for eddy current loss mitigation, two different materials are investigated and compared for the same winding design, namely copper and aluminum. Using the finite element method (FEM), the conductor loss and current density behavior are simulated at the strand level. Further, in order to verify the simulated losses, the AC losses are measured and compared over a wide range of frequencies. Finally, recommendations are provided based on the obtained measurements to identify the best winding topology that is most suitable for automotive applications.

This paper presents a new three-phase flux switching generator (FSG), which is mainly designed for variable-speed low power wind turbines. The magnetless structure of this generator not only reduces the machine cost but also increases the flux controllability. In order to shorten the field and armature end-windings, non-overlapped concentrated windings have been ingeniously incorporated into the dual-rotor middle-stator structure. A parametric study of both stator and rotor pole arcs is carried out, targeting maximum generated EMF, and minimum cogging torque. Using finite element method, the performance of the final design is analysed. Through the ac-dc rectification, the generated EMF is rectified to give out the dc output voltage, which can be regulated by controlling dc excitation current, and accordingly, the machine can behave as a constant-output dc generator under different conditions of rotor speeds and load currents. Finally, a prototype has been manufactured and experimented to prove its validity for dc microgrids integrated with wind generation systems.

Recent advances in electrical machines and energy storage technologies make electric vehicles (EVs) feasible replacements to conventional internal combustion engines. One of the main challenges of high speed electrical machines is providing maximum output power with minimum energy losses, weight, and volume. At high frequency operation, the conductors of AC electrical machines can suffer from skin and proximity effects. This results in high AC losses in the machine windings and can eventually lead to machine failure. In this paper, a novel design for a semi-stranded coil is proposed to limit these undesirable effects. Enabled by additive manufacturing (AM) technology, this sophisticated design is 3D printed using ultralight aluminum alloy. Finally, the AC performance of this coil is measured and compared with conventional single-strand copper coil at different frequency levels. It is found that the proposed design can effectively limit the eddy current losses in the high frequency domain.