1,720,979 research outputs found
Multi-Objective Optimization of Medium-Scale Wound-Field Electric Generators
No full textThis work deals with the optimization of electric generators for multiple performance measures, e.g., the simultaneous maximization of the fundamental harmonic and the minimization of the total harmonic distortion of the Back-EMF. For a given slot/pole-configuration and pole span, the goal is to find the optimal rotor outer contour along the air gap. Different approaches for modeling the rotor contour are followed here, i.e., a Fourier-series based approach and a piecewise discretization of the circumference. The work is about performing optimizations for both approaches and to compare the achieved results (i) when considering similar computational effort, (ii) regarding modeling complexity versus design flexibility, and (iii) the possibility for acquiring additional information, as for instance the sensitivity of the contour regarding manufacturing tolerances
Loss Modeling for Interlocked Magnetic Cores
No full textIn mass production, interlocks are an affordable staking solution for magnetic cores of electrical machines. However, the interlock dowels introduce an increase of core losses, not only for the appearance of conductive paths in the interlock regions, but also for a non-negligible worsening of the magnetic material properties (including the hysteresis losses), both inside the interlocks and in the surrounding areas. This study aims at developing a reliable and accurate three-dimensional FEM model that takes into account the contact resistance between interlocks and laminations, as well as layered regions constituted by damaged materials. The paper includes modelling hints and the fine-tuning of the 3D FEM that includes a detailed modeling of the interlock section. Examples of flux and eddy current density distributions are provided, together with the computation of the total iron losses for a variable number of rectangular dowels in the yoke of stator core samples. The numerical results are validated by experimental measurements conducted on multiple samples having different number of interlocks
A Thermographic Method to Evaluate Different Processes and Assembly Effects on Magnetic Steels
No full textFerromagnetic materials may be affected by the presence of local losses due to defects or magnetic anomalies caused by machining processes. To highlight such anomalies is not easy; a noninvasive thermographic method has been refined to allow a proper comparison of different machining processes' impact on the iron losses. Specimens obtained with punching, wire erosion, and laser cut have been analyzed using a high-speed IR camera when subjected to alternate magnetization at different frequencies. Also, the same technique has been adopted to the assembled stacks to investigate more simultaneous phenomena. The possibility to point out localized anomalies should be exploited to foresee and avoid electrical machines core faults
Application of new magnetic materials for axial flux machine prototypes
No full textThe experience recently gained by the authors in the field of production and testing of new magnetic materials, especially developed for small electric machines, has been applied to the production of an axial flux permanent magnet motor prototype. In particular, different materials have been used for the stator and the rotor core, together with low-cost bonded permanent magnets; the machine under investigation is equipped with fractional slot windings and foils conductors insulated by a dedicated electro-deposition process. The design and the production of all the machine parts, as well as the experimental activities, have been performed and carried out by the research team at their Universities, without outsourcing needs. The design and FEM simulation results have been validated by means of comparison with experiments, obtaining good agreements
Experimental Assessment and Modeling of Losses in Interlocked Magnetic Cores
Full text linkThe use of interlocks often represents an affordable stacking solution for soft magnetic cores in mass production of electrical machines. However, due to the process itself, the material behavior and thus the resulting electrical machine performance is negatively impacted. On the one hand, this is due to additional conductive paths, which increase the eddy current losses. On the other hand, locally introduced mechanical stresses occur. These lead to nonnegligible degradation of the magnetic material properties inside and around the interlock area, following higher hysteresis losses. This article investigates and develops a reliable and accurate three-dimensional finite-element method model that considers the contact resistance between interlocks and laminations, as well as layered regions for the material degradation around the interlock area. Examples of flux and eddy current density distributions are provided, together with the computation of the total iron losses for a variable number of rectangular dowels in the yoke of stator core samples. The numerical analyses are validated by several interlaboratory measurements conducted on multiple stator core samples made of two different grades of electrical steels and with different numbers of interlocks. Results reveal impact of some percent on the core losses and well evident degradation on the material BH curve
A Thermographic Method to Evaluate Different Processes Effects on Magnetic Steels
No full textFerromagnetic materials may be affected by the presence of local losses due to defects or magnetic anomalies caused by machining processes. To highlight such anomalies is absolutely not easy; a non invasive thermographic method has been refined to allow a proper comparison of different machining processes impact on the iron losses. Specimens obtained with punching, wire erosion and laser cut have been analyzed by means of a high speed IR camera when subjected to alternate magnetization at different frequencies. The possibility to point out localized anomalies should be exploited to foresee and avoid electrical machines core faults
Application of new magnetic materials for axial flux machine prototypes
No full textThe experience recently gained by the authors in the field of production and testing of new magnetic materials, especially developed for small electric machines, has been applied to the production of an axial flux permanent magnet motor prototype. In particular, different materials have been used for the stator and the rotor core, together with low-cost bonded permanent magnets; the machine under investigation is equipped with fractional slot windings and foils conductors insulated by a dedicated electro-deposition process. The design and the production of all the machine parts, as well as the experimental activities, have been performed and carried out by the research team at their Universities, without outsourcing needs. The design and FEM simulation results have been validated by means of comparison with experiments, obtaining good agreements
More Robust and Reliable Optimized Energy Conversion Facilitated through Electric Machines, Power Electronics and Drives, and Their Control: State-of-the-Art and Trends
No full textAccording to the special section entitled 'Robust design and analysis of electric machines and drives', to be published in IEEE Transactions on Energy Conversion, the authors present an introduction to tolerance analysis, robust optimization, and measures to improve the reliability of electric machines, power electronics and drives, and their robust control in general. A comprehensive review of modeling uncertainties and evaluating robustness and reliability based measures is presented. In addition, techniques facilitating solving dedicated optimization scenarios are introduced. The most recent research activities will be illustrated. The article thus enables to easily catch up with the state-of-the-art in these fields and to take notice of ongoing and future work
Approaches for Improving Lumped Parameter Thermal Networks for Outer Rotor SPM Machines
Full text linkThis work is about the transient modeling of the thermal characteristics of outer rotor SPM machines by considering a lumped parameter thermal network based approach. The machine considered here poses particular challenges for the modeling, e.g., due to the semi-closed stator surrounded by a rotor bell that provides a speed-dependent cooling of the stator coils. Starting from a simpler basic network configuration, model extensions and refinements are presented and discussed. The subsequent parameter identification is done by means of an initial design of experiments based sampling, and a subsequent single-objective and also a multi-objective optimization of error functions for the components' temperatures. Analyzing the therefrom derived Pareto fronts and the consequent tradeoff regarding achievable minimum modeling errors for different system's components gives insights into where and how the modeling can be further improved. All the investigations are based on experimental results obtained through operating a particularly developed test setup
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