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Noise, vibration, and harshness (NVH) issue in switched reluctance machines (SRMs), originating from their doubly salient structure and unique principle of operation, is addressed in this work by proposing a structural design modification in the stator, which increases stiffness to mass ratio of the structure. A 24-slot 16-pole (24s/16p) SRM designed with the aim of automotive application is studied here for the NVH optimization, at different target operating points, using stator pole bridges. Stator pole bridges link consecutive stator teeth to provide additional stiffness to the stator structure. Average torque reduction due to flux shorting in stator pole bridges is tackled by proposing a low-permeability material, with considerable stiffness, which has not yet seen its’ application in SRM NVH domain. Multiphysics aspects of stator pole bridge design encompassing electromagnetic radial force, mechanical stress, steady-state temperature distribution, and acoustic noise analyses are presented in this article. Possible manufacturing issues are considered during the design phase and appropriate measures are implemented to facilitate easier construction of two 100-kW prototypes. The final design with stator pole bridges and a baseline design without any stator pole bridges are prototyped, after rigorous multiphysics optimization, for extensive testing. Experimental results verify simulation outputs and report a maximum noise reduction of 12.52 dBA in the stator pole bridge model compared to the baseline SRM.

Switched reluctance machines (SRMs) generate high torque and radial force ripples which results in acoustic noise and mechanical vibrations. It has been a challenge to reduce vibrations while maintaining the high power densities for SRMs. This paper proposes a simultaneous torque and radial force ripple reduction algorithm using multi-objective current profile optimization for a DQ-Controlled SRM. 3D mechanical and Acoustic FEA are performed to assess the performance of the proposed algorithm compared to conventional one in reducing acoustic noise and vibrations. The FEA simulation results demonstrated that the optimized current profile using proposed method reduces the acoustic noise by 11 dBA at rated operating conditions.

Switched Reluctance Machines (SRMs) have been studied by many researchers as an alternative to other types of electrical machines for use in electric and hybrid vehicle applications. SRMs are fault tolerant and have wide speed operating range. However, they suffer from several disadvantages including high vibration, acoustic noise and torque ripple. In this paper, placement of rectangular windows in both the rotor and stator poles is proposed to reduce the vibration and acoustic noise of SRMs. The position and the dimensions of the windows are optimized through Electromagnetic Finite Element Analysis (FEA). Multi-physics FEA is also performed to predict the vibration and acoustic noise of the optimized design. The results of this study confirm that placing windows in both the stator and the rotor of the SRMs can significantly reduce the acoustic noise compared to conventional SRMs.

This study investigates the effect of different skewing methods and angles for switched reluctance machines (SRM) having high pole count using multiphysics simulations. A 24/16 SRM is modeled for each skewing method and different skewing angles using 3D electromagnetic finite element analysis (FEA). Mechanical and acoustical analyses are performed to evaluate the effectiveness of different skewing methods. The results for each method are compared for the same torque levels. For Stator-only and Rotor-only skewing methods, torque output drops significantly, which reduces the effectiveness of these methods in achieving desired torque levels. However, implementing skewing on both the stator and rotor together has less impact on the torque production and has a significant impact on distributing the radial force on the stator back iron. Given an SRM designed to achieve 150kW of output power, multiphysics simulations predict a 10.5 dBA reduction in the acoustic noise for an optimized rotor/stator skewing angle of 13.5°.

High vibration and acoustic noise are known to be the most dominant disadvantages for utilizing SRMs in Hybrid electric vehicles or home appliance applications. One of the methods for mitigating these disadvantages is to introduce windows in the SRM structure to reduce the magnitude of the radial force responsible for stator deformation. Previous studies are focused on introducing windows in the rotor. This paper investigates the effectiveness of introducing windows in the stator or rotor laminations of SRMs. An optimization process was first done based on finite element electromagnetic analysis to determine the best windowing design for both stator and rotor. Afterwards, mechanical structural analysis was conducted to compare the vibration and acoustic noise performance of the two methods with the conventional SRM.

Switched reluctance machines (SRMs) have been studied by many researchers as an alternative to the other types of electrical machines for use in electric and hybrid vehicle applications. SRMs are fault tolerant and have wide speed operating range. However, they suffer from several disadvantages, including high vibration, acoustic noise, and torque ripple. In this article, the placement of rectangular windows in both the rotor and stator poles is proposed to reduce the vibration and acoustic noise of SRMs. An iterative optimization algorithm in a wide speed range of operation using finite-element analysis (FEA) tools provides the best position and dimension of window design parameters. Multiphysics FEA is also performed to predict the vibration and acoustic noise of the optimized design. The results of this study present that placing windows in both the stator and rotor of the SRMs can significantly reduce the acoustic noise compared with the baseline SRMs. Based on the simulation results, the optimum design has been constructed as a prototype and tested in a wide speed operating condition. The simulation and experimental test validation results prove the effectiveness of the proposed design in mitigating the acoustic noise and vibration.

As commercial operating systems such as Microsoft Windows move from the desktop to the embedded world and low-power, low-cost embedded CPU performance increases the distinction between dedicated embedded systems and laboratory demonstration systems is blurring. Signalscape, Inc. has developed a highly flexible acoustic signal processing system with real-time performance on Pentium II class desktop computers running Microsoft Windows. In a recently awarded DARPA program, Rockwell Science Center, Signalscape, and their partners are moving the flexibility and capabilities of Signalscape's many tool kits onto low-cost, low-power systems for unattended sensor applications. In this paper we discuss the results of the first demonstrations of acoustic beamforming using a small network of sensors.