Viscoelastic property tuning for reducing noise radiated by switched-reluctance machines

Abstract

Switched-reluctance motors (SRM) present major acoustic drawbacks that hinder their use for electric vehicles in spite of widely-acknowledged robustness and low manufacturing costs. Unlike other types of electric machines, a SRM stator is completely encapsulated/potted with a viscoelastic resin. By taking advantage of the high damping capacity that a viscoelastic material has in certain temperature and frequency ranges, this article proposes a tuning methodology for reducing the noise emitted by a SRM in operation. After introducing the aspects the tuning process will focus on, the article details a concrete application consisting in computing representative electromagnetic excitations and then the structural response of the stator including equivalent radiated power levels. An optimised viscoelastic material is determined, with which the peak radiated levels are reduced up to 10 dB in comparison to the initial state. This methodology is implementable for concrete industrial applications as it only relies on common commercial finite-element solvers.

Damping control for improvement of acoustic black hole effect

“…The aim of the heat control is to tune the mechanical properties of the viscoelastic material: it is well known for years that their stiffness and damping properties are strongly dependent on frequency and temperature [19,20,21]. Many works hence focused on the effect of the temperature on the structural damping performances [22,23,24] or on the optimization of the viscoelastic properties for a given ambient temperature [25].…”

On the structural dynamics of laminated composite plates and sandwich structures; a new perspective on damping identification

“…The frequency evolution of the loss factors estimated by the present model (see Figure 7) are coherent with Backström's results. Such frequency dependence of the loss factor of sandwich structures has already been studied by Millithaler et al [34] or Ege et al [14,35] for a viscoelastic core, and by Butaud et al [36] for a Shape Memory Polymer core. Whatever the method used, the loss factors reach a maximum at a certain frequency, depending on the structural dynamic parameters of the layers.…”

Technology Development of Electric Vehicles: A Review

“…Jing et al [140] explored a new type of rotor profile to minimize the torque ripple of the SRM. Millithaler et al [141] employed an optimized viscoelastic resin to encapsulate/pot an SRM stator for reducing the noise in operation. Klein-Hessling et al [142] used a search algorithm to forecast proper reference values for each phase to keep torque and overall radial force balanced at any time and remove two central drawbacks of SRMs.…”