Multiphysic Design and Modeling of Rotating Electrical Machines

This paper presents a general overview on design process of electrical machines considering a multiphysic point of view, and a road map for a comprehensive design approach is drawn. The objective multi-physical criterion including electromagnetism and mechanics physics, thermodynamics, fluid dynamics, structural dynamics, noise and vibration are discussed. Also, various modelling methodologies are presented and compared in terms of computational-time resources and accuracy. Current state of art in this approach will be presented highlighting the advantages and disadvantages of such methodologies

Effects of dynamic eccentricity in Flux Switching Permanent Magnet machines

This paper investigates the effect of rotating eccentricity fault on a 10/12 Flux Switching Permanent Magnet (FSPM) machine. Main characteristics of the studied machine such as air-gap flux density, magnetic force between rotor and stator and torque profile are calculated by using finite element analysis (FEA) which is the most accurate numerical method. Furthermore, Fourier analysis is performed in order to study the impacts of rotating eccentricity faults on magnetic force and torque profiles. In addition, the results of Fourier analysis of the machine in healthy condition are compared with the machine with 40% rotating eccentricity. This studies shows that the eccentricity has significant effects on FSPM characteristics which shows the importance of investigating the fault. To the best awareness of the authors, the effects of the rotating eccentricity on FSPM machines have not been studied before

Non-Invasive Measurements and FEM Analyses for Estimating the Rotor Bar-Lamination Contact Resistance

This research work investigates the phenomenon of interbar currents in induction motors equipped with die-cast alu- minum cages. Flowing in the lamination and distorting the bar current distributions, the interbar currents cause additional stray losses as well as an increase of the joule loss in the cage bars. The contact resistance between the bars and the rotor lamina- tions is the key modeling element for a correct prediction of the interbar currents and the related extra losses. The study presents a new noninvasive method to obtain a reliable estimation of the contact resistance. The proposed hybrid approach is based on a mix of experimental data and Finite Element method (FEM)-based simulation results. A reliable three-dimensional FEM model of a four-pole 15-kW induction motor with closed rotor slots has been used to investigate the impact of variable contact resistance on the interbar currents, rotor joule losses, and the voltage drops along the bars, opening a new perspective 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

Electromagnetic and Thermal Evaluation of Surface-Mounted PM Vernier Machines

This study investigates the electromagnetic and thermal performance of surface-mounted permanent magnet vernier machines. In particular, different losses and thermal behaviour of PM vernier machines are evaluated considering different gear ratios and the obtained results are compared with a baseline conventional PM machine. In order to have a fair evaluation of the studied machines, the stator and rotor dimensions, as well as current density in the slots, are kept constant, while the stator winding poles and the PM poles mounted on the rotor are varied. The performances of all the machines are evaluated using 2D finite element analyses. Back-EMF, output torque, torque ripple, losses and efficiency are evaluated for the studied machines together with their weight / volume comparison. Finally, thermal analyses are carried out and the impact of temperature on the machines is investigated

Static eccentricity fault detection in Flux Switching Permanent Magnet machines

This paper studies the effects of static eccentricity (SE) in Flux Switching Permanent Magnet (FSPM) Machines to propose a criterion for fault detection. SE is one of the most common mechanical faults in electrical machines on. In order to achieve this goal, the proposed machine is studied under different degrees of static eccentricity fault to analyze machine condition. Finite element modeling (FEM) as the most accurate numerical approach is used to obtain precise results. The magnetic flux distribution of rotor and stator are calculated. In addition, air-gap flux density as a parameter which has a direct impact on back-EMF is assessed by using finite element analysis (FEA). It is found that static eccentricity has noticeable influences on back-EMF of coils of the machine. Furthermore, Fourier analysis is performed in order to achieve appropriate index for the diagnosis process. The results are provided for the healthy machine and the machine with different values of SE and the proposed index has been derived for the fault detection process in the machine

Analysis of Proximity Loss of Electrical Machines Using Mesh-Based Magnetic Equivalent Circuit

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

AFPM Machines Equipped with Multilayer Magnets

This article investigates the manufacturability and applicability of unified multilayer magnets, comprising two different magnetic materials with distinct characteristics, for use in electrical machines. In particular, the self-produced multilayer magnets are made of compressed NdFeB bonded powders for the ‘strong’ magnet layer and hybrid composite materials for the ‘weak’ magnet layer. Various combinations of material for the self-produced permanent magnets are experimentally investigated. Also, the suitability of resultant multilayer bonded magnets to electrical machines is articulated on the basis of finite element simulations. To assess their performance, three axial-flux surface-mounted permanent magnet machines are constructed: one conventional machine with single-layer bonded magnets as the reference, and two machines equipped with multilayer magnets with series and parallel configurations. The performance of the machines are evaluated in terms of the back-EMF, output torque, torque ripple, losses, efficiency, and cost. The findings indicate an appreciable enhancement in flux-weakening operation for the machine equipped with multilayer magnets, but at the expense of lower flux linkage values and nominal torque. Further analyses of the multilayer magnet's trade-offs and potential applications in electrical machines are presented

Multiphysics Design of Interior Permanent Magnet Machines and Characterization of Innovative Hard Magnetic Material

L'abstract è presente nell'allegato / the abstract is in the attachmen

Electromagnetic sizing of axial-field flux switching permanent magnet machine

This paper presents a general sizing procedure of axial-field flux switching permanent magnet (AF-FSPM) machine for various topologies. A comprehensive approach is used for design of AF-FSPM machine and the design flowchart is presented. A three phase, 12/10 single-stage AF-FSPM machine is designed and three dimensional finite element analyses are performed to validate the design procedure. The magnetic flux distribution, induced EMF, and cogging torque has been computed. It is found that the results confirm the presented procedure

Manufacturing and Characterization of Novel Multilayer Magnets for Electrical Machine Applications

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