In high power density machines, proximity loss presents an unavoidable obstacle due to its significant impact on thermal dissipation and insulation aging. To address the need for rapid and accurate proximity loss prediction, this study presents a novel methodology that employs a mesh-based magnetic equivalent circuit (MEC) for calculating proximity loss in electrical machines. Using an existing machine as an example, the proposed approach is applied to various scenarios, yielding results that demonstrate close agreement with both finite element analysis (FEA) and experimental results, validating its effectiveness. Notably, the technique exhibits high flexibility and can be extended to accommodate slots of various shapes. This innovative approach, which involves flux leakage calculation, represents a previously unexplored avenue and could potentially serve as a fundamental basis for expeditious AC loss calculations.

This paper presents the concept of efficiency mapping for large synchronous hydrogenerators, which are useful for evaluating hydropower generation performance vis-à-vis interconnected intermittent generation to machine efficiency-oriented design. Tests for loss segregation at rated conditions are needed, and models for loss variation along all operational areas are presented. The weighted average efficiency is obtained as the summation of all operating load point efficiencies times related weights, defined according to criteria or from a 2D-histogram of machine operation. The proposed methodology is applied and compared for two machine designs and to an existent machine under operation.

This study introduces a novel method to rapidly estimate the circulating current between the strands in electrical machines. By utilizing mesh-based magnetic equivalent circuit (MEC), key parameters of each strand are obtained based on their positions in the slot and used for circulating current calculation. The modelling and calculation process of the proposed method is demonstrated using a permanent magnet synchronous machine (PMSM) as baseline. The results calculated from the proposed method closely align with those from finite element analysis (FEA) and are further supported by experiments conducted on a segment of the stator, validating the effectiveness and efficiency of the proposed method. Notably, the proposed technique is applicable for various slot shapes and machine types, serving as a powerful tool for optimizing winding to minimize AC losses.

This study presents a sizing methodology in the frame of the multidisciplinary design of interior permanent magnet synchronous machines. The proposed approach targets at obtaining an initial electromagnetic design of the machine, including diameters, axial length, rotor barrier shape, stator slot geometry as well as the winding layout. The analytical design workflow consists of an iterative sizing procedure based on a robust geometric model, consistent equations, and no correction factors. The process is carried out starting from very basic design parameters such as rated voltage, torque, and magnetic material properties. The modular structure of the proposed design algorithm can be easily integrated with optimization routines obtaining a final optimized design, which contemplates various multiobjective constraints.

This research work investigates the phenomena of inter-bar currents in induction motors equipped with die-cast aluminum cages. Flowing in the lamination and distorting the bar current distributions, the inter-bar currents cause additional stray losses, as well as increase of the Joule loss in the cage bars. The contact resistance between the bars and the rotor laminations is the key modeling element for a correct prediction of the inter-bar currents and the related extra losses. The study presents a new non-invasive method to obtain a reliable estimation of the contact resistance. The proposed "hybrid" approach is based on a mix of experimental data and FEM-based simulation results. A reliable 3D-FEM model of a 4-poles 15 kW induction motor, with closed rotor slots, has been used to investigate the impact of a variable contact resistance on the inter-bar currents, rotor Joule losses, and the voltage drops along the bars, opening a new prospective for this complex phenomenon and its impact on the stray losses. Finally, the proposed methodologies are critically discussed and the obtained results compared with other relevant research works.

This paper presents the potentialities of diverse kinds of permanent magnet materials in order to build and characterize multilayer magnets, as well as to investigate their prospective application in electrical machines. In particular, bonded magnet and hybrid magnet powders are used to build two-layer samples, which pave the way for constructing special electrical machines with complex magnetic structures, such as the variable flux permanent magnet machines. In this study, samples of innovative double-layer magnets are built through a single press and the following magnetization procedure. A particular electromagnetic circuit is adapted to experimentally achieve the demagnetization characteristic to estimate the air gap magnetic flux behaviour in electrical machines. The measurement system flexibility allowed the testing of two double-layer magnets: the so-called parallel and series arrangements.