Créteil, France


Créteil, France
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Le Goff V.,EuroXA | Vidal V.,EuroXA | Fakes M.,Valeo EEM | Chiozzi P.,Valeo EEM | And 3 more authors.
Proceedings of the ASME Turbo Expo | Year: 2014

The increasing demand for comfort and quietness from the automotive industry transforms the acoustics performances of subsystems as a critical input for the selection of a specific design. Among this market, rotating systems noise takes a growing importance and automotive alternators are strongly impacted by this aspect. Alternators contain many different types of rotating parts such as cooling fans and claw poles and their corresponding flow-induced noise contributions and interaction mechanisms driving the noise generation have to be assessed as early as possible in the product development process. Experimental methods have been historically used to identify and reduce the most obvious phenomena at the origin of the broadband and tonal contents of the noise. Considering the complexity of this device, it appears practically more and more difficult to understand the involved mechanisms and to identify and treat the remaining aeroacoustics sources. The use of digital solutions to simulate the corresponding flow-induced noise contributions and to provide an insight on the noise generation mechanisms represents an alternative to this experimental approach. Furthermore, numerical approach allows a broader design space exploration, where experimental testing can sometime be limited by other constraints, such as mechanical, thermal and electromagnetic aspects. Another advantage of using CAE method is to reduce the product development cycle and the number of expensive prototypes. The highly detailed geometry features and the constrained environment of alternators however represented a real challenge for computational aeroacoustics solutions. In this paper, an unsteady and compressible computational approach based on the Lattice Boltzmann Method (LBM) is used to simultaneously predict the 3-D turbulent flow and the corresponding acoustic field of an automotive alternator. The complete rotor-stator model including all geometrical details and the truly rotating geometry is simulated. Numerical and experimental far field sound pressure levels and acoustic power comparisons are presented. Additional transient and spectral flow analysis are performed to diagnose flow-induced noise problems and to provide a better understanding of the aeroacoustics sources. © 2014 by ASME.

Lu L.,Arts et Metiers ParisTech | Aslan B.,Arts et Metiers ParisTech | Kobylanski L.,VALEO EEM | Sandulescu P.,Arts et Metiers ParisTech | And 3 more authors.
IECON Proceedings (Industrial Electronics Conference) | Year: 2012

Multi-phase synchronous machines are more and more used in specific applications where high power density, low bus voltage, wide speed range and fault-tolerant capabilities are required. Due to the high number of degrees of freedom, multi-phase machines are difficult to optimally operate in flux-weakening zones. This paper proposes a technique to numerically compute optimal current references that can be used for feed-forward flux-weakening techniques in order to exploit the maximum machine performances for given DC bus voltage and current limits. The proposed technique is applied to a five-phase permanent magnet synchronous machine specifically developed for an automotive application. © 2012 IEEE.

Aslan B.,Arts et Metiers ParisTech | Semail E.,Arts et Metiers ParisTech | Korecki J.,Arts et Metiers ParisTech | Legranger J.,VALEO EEM
IECON Proceedings (Industrial Electronics Conference) | Year: 2011

This paper presents multiphase permanent magnet machines with concentrated non-overlapped winding as a good candidate for automotive low voltage mild-hybrid applications. These machines often require a trade-off between low speed performances such as high torque density and high speed performances like flux weakening capabilities. This paper describes how to choose a key design parameter to ease this compromise, the slots/poles combination, according to three parameters: winding factor including harmonics factor, rotor losses amount thanks to a comparison factor, and radial forces balancing. The comparison criterions are based on both analytical formula and Finite Element Analysis. © 2011 IEEE.

Aslan B.,Arts et Metiers ParisTech | Semail E.,Arts et Metiers ParisTech | Legranger J.,VALEO EEM
2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012 | Year: 2012

This paper studies magnet eddy-current losses in permanent magnet (PM) machines with concentrated winding. First of all, space harmonics of magnetomotive force (MMF) and their influence on magnet losses in electrical machines are investigated. Secondly, analytical model of magnet volume losses is developed by studying the interaction between MMF harmonics wavelengths and magnet pole dimensions. Different cases of this interaction are studied according to the ratio between each harmonic wavelength and magnet pole width (following flux density variation). Then various losses sub-models are deduced. Finally, using this analytical model, magnet volume losses for many slots/poles combinations of 3, 5, and 7 phase machines with concentrated winding are compared. This comparison leads to classify combinations into different families depending on their magnet losses level. Besides, in order to validate the theoretical study, Finite Element models are built and simulation results are compared with analytical calculations. © 2012 IEEE.

Aslan B.,Valeo EEM | Savinois O.,Valeo EEM | Mipo J.-C.,Valeo EEM | Farah P.-S.,Valeo EEM
2014 IEEE Vehicle Power and Propulsion Conference, VPPC 2014 | Year: 2014

In this paper a comparison between a 5 and 6 phases alternator is achieved. The target is to show how the 5-phase structure may influence the alternator performance comparing with a classical 6-phase configuration. Current and voltage harmonics of both 5 and 6 phases alternator provided with a bridge rectifier are analyzed. The impact of the phase current third harmonic on the output power in 5-phase configurations is examined. Phases RMS currents generated in the studied structures are compared considering the same output current. The different studies realized in this paper are based on both finite elements (FE) simulation results and a five-phase prototype measurements. © 2014 IEEE.

Sanfins W.,National Polytechnic Institute of Toulouse | Sanfins W.,CNRS LAPLACE Lab | Risaletto D.,National Polytechnic Institute of Toulouse | Risaletto D.,CNRS LAPLACE Lab | And 5 more authors.
Microelectronics Reliability | Year: 2015

Direct-lead-bonding (DLB) and wire-bonding, in epoxy-moulded package, are compared in terms of functional characteristics, failure-mode and post-fault high-current capability of a dual-chip power module (PM), with respect to I2T and critical energy. Wire-bonding power modules have shown poor thermal behaviour, a high and unstable RCE (the chip fault residual resistance), and sometimes a fuse-effect when used in gel-filled power modules. However, DLB power modules demonstrated a very good thermal and electrical behaviour, a very low and stable RCE under high energy failure. After non-destructive defect localization thanks to Lock-In Thermography coupled to RX tomography, the authors were able to confirm the formation of a metallic bridge under wire-bondings and through the chips and solder in DLB, which explains low RCE values for this technology. The DLB interconnection appears to be a promising technology for power module. Nevertheless, the absence of wire-fuse-effect in case of extreme failure, compared to classical wire-bonding, leads the authors to rethink fail-safe and fault-tolerant strategies for critical converter. © 2015 Elsevier Ltd.

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