31,136 research outputs found
Codro, re d'Atene : azione accademica : da rappresentarsi nel giorno natalizio del serenissimo signor principe di Modena nel Ducale Teatro Grande : composta, recitata, e dedicata all'Altezza Serenissima di Rinaldo I., duca di Modena, Reggio, Mirandola &c. /
No full textSignatures: *⁴ A-F⁴ G².Final leaf blank.Mode of access: Internet.Library's c.2 bound with: Publio Scipione Emiliano. Modena : Capponi, 1733 (94-B19516)Library's c.1 bound with: Il valore magnanimo d'Alessandro nella sconfitta del re Porro. Modena : Antonio Capponi, 1722 (94-B19419
Foreword of the special issue on Alps and Apennines: a natural laboratory for Structural Geology and Geodynamics
No full textComprehensive Analysis of Extended Electro Motive Force Observers for Position Estimation in Interior Permanent Magnet Synchronous Machines
No full textExtended Electro Motive Force observers exhibit good performances at medium and high speeds. However, voltage and current errors, together with parameter uncertainties, lead to inaccurate rotor position estimation. Thus, this paper proposes a novel analytical approach to identify estimated position errors of Extended Electro Motive Force Observers in both the stationary and the estimated synchronous reference frames. A unified analytical framework is presented, that allows to derive a closed-form expression for these errors in both frames. Steady state errors are extensively investigated with respect to stator resistance mismatch, inductances mismatch, voltage distortion, and current measurement errors. Results are validated through simulations
A saturation model based on a simplified equivalent magnetic circuit for permanent magnet machines
No full textThis paper proposes an explicit mathematical model to describe the nonlinear behavior of the permanent magnet synchronous reluctance machine. Although different models for the synchronous reluctance machines are available, extending them to the case of the permanent magnet machine is not trivial due to the effect of the permanent magnets on the rib saturation. This work uses a simplified equivalent magnetic circuit to derive the structure of the proposed model. A nonlinear reluctance is introduced to model the rib saturation. It can be added to the existing model for the synchronous reluctance machine to take into account the effect of the permanent magnets. A simple fitting procedure based on the steepest descent method is proposed to estimate the parameters of the model
Design of a high speed printed circuit board coreless axial flux permanent magnet machine
No full textThe use of printed circuit board stators in coreless axial flux permanent magnet machines allows to reduce manufacturing costs and to eliminate the main drawbacks of traditional implementations using Litz wire. This work investigates the design of a coreless axial flux permanent magnet machine having printed circuit board concentrated windings. The field model of the coreless machine is reviewed to obtain closed-form equations for torque, eddy current loss and circulating currents loss are presented. Furthermore, cardinal geometrical parameters of the printed circuit board stator and the latest manufacturing possibilities are investigated, followed by the presentation of important machine design details
A Comparative Study of Stator Winding Technologies for Coreless Axial Flux Permanent Magnet Machines
No full textRecently, axial flux permanent magnet machines with coreless windings have been proposed for many applications, from low-speed servo systems to high-speed electric propulsion. These machines have zero cogging torque and core losses, a highly linear behaviour, and remarkable overload capabilities. Conversely, thermal behaviour, efficiency, torque density and power density strongly depend on the specific stator winding technology. This paper reviews stator winding technologies for coreless axial flux permanent magnet (AFPM) machines, focusing on their potential benefits and limitations. Additional contributions include the analysis and comparison of different winding solutions for low-speed and high-speed machines. The presented results can be used as guidelines for the selection of the most appropriate winding technology for a number of practical applications
Design of a Printed Circuit Board Axial Flux Permanent Magnet Machine for High Speed Applications
No full textRecently, printed circuit board (PCB) stators have been proposed for coreless axial flux permanent magnet machines to reduce manufacturing costs and eliminate some of the drawbacks of traditional Litz-wire-based stators. However, their design presents significant challenges. Firstly, the PCB copper traces are exposed to the rotating air-gap field, which causes significant high-speed AC losses. Secondly, standard PCBs hardly satisfy stator winding requirements since the achievable copper fill factor is rather limited. In order to address these issues, the paper proposes a bespoke machine design methodology which relies on original closed-form expressions for eddy and circulating current losses. Additionally, the most recent PCB technological developments are considered in the determination of manufacturing constraints. A case study is provided for a 1 kW, 7500 rpm machine to validate the design method. An original winding layout is proposed to suppress circulating losses. Finally, an extensive set of experimental tests on a full-scale prototype is reported
Re: Vincent Cloutier, Umberto Capitanio, Laurent Zini, et al. Thirty-Day Mortality after Nephrectomy: Clinical Implications for Informed Consent. Eur Urol 2009;56:998-1005
No full textOn the effects of position sensor resolution in variable speed drives
No full textThe aim of this paper is to further the knowledge on the inherent limitations imposed on variable speed drives by the resolution of the rotor position sensor. Starting from the well-known spatial harmonic formulation of quantized rotor position measurement, time harmonic formulations of both quantized position and speed are derived, which are valid under generic periodic torque disturbances. These formulations, based on modulation theory, justify the presence of otherwise unexplained additional rotor speed harmonics that are induced by the drive when subjected to torque disturbances. Simulations are provided to verify the correctness of the proposed mathematical representations
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