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Multiphysics analysis and experimental validation of acoustic noise reduction in a high pole count, high power, switched reluctance machine (SRM), through skewing are explored in detail in this work. An iterative optimization strategy covering electromagnetic, structural, and thermal domains is proposed to investigate the effect of different skewing methods and angles on a 24-stator slot/16-rotor pole (24/16) SRM rated at 100 kW. The contributions of this work are twofold. First, electromagnetic impact, considering average torque, torque ripple, radial and tangential air gap forces, of symmetric and asymmetric skewing on stator and rotor is studied in this work. Second, the impact of skewing methods on acoustic noise and vibration performance is studied and presented in detail. The study reveals that skewing both the stator and rotor by the same amount has superior electromagnetic performance over other types of skewing. Multiphysics simulations conducted, predict a 10.5 dBA reduction in the acoustic noise, compared to a baseline design with no skew, for an optimized rotor-stator skewing angle of 13.75°. Finally, 100 kW prototypes of the baseline and the optimized skewed SRM were constructed and subjected to wide speed range testing. Simulation and test results closely follow each other and validate the effectiveness of the proposed skew design in mitigating acoustic noise and vibration in high pole count SRMs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Acoustic noise reduction is one of the main topics of switched reluctance motor (SRM) developments. One of the effective methods is flattening three-phase radial force sum. This method is verified in experiments by optimizing the current profile. Novel current waveforms have been proposed recently for acoustic noise reduction without sacrificing the efficiency in the 18/12 SRM, which has competitive power density, torque density, peak efficiency, and outer dimensions compared with the permanent magnet motor employed in hybrid electric vehicles. In this article, electro-mechanical analysis and acoustic analysis are carried out to verify acoustic noise reduction in the 18/12 SRM. The relationship between radial force sum Frsum, torque ripple Trip, and acoustic noise is investigated. Experimental confirmation is also included. [ABSTRACT FROM AUTHOR]

Switched reluctance machine (SRM) drive requires a large dc-link capacitor due to the low-frequency harmonics in dc-link current, which is generated during the current commutation between phases. Installing a bulky capacitor bank in the drive has a significant impact on the cost and the overall volumetric power density of the drive. This article analyzes the dc-link current ripple in SRM drive and proposes a control algorithm to reduce the dc-link current ripple while maintaining the machine performance. The proposed algorithm extracts the ripple components from the dc-link current using a high-pass filter. The controller ensures ripple energy circulation between the phases and reduces the pulsating energy requirement from the dc supply. The dc-link ripple is suppressed at a wide speed range of operation to enable efficient and reliable drive operation without adding any external hardware system. Simulation and experimental results are provided to prove the effectiveness of the proposed control technique for both steady-state and transient conditions. [ABSTRACT FROM AUTHOR]

With growing interest in electrification in automotive industries, the selection of suitable electric machine types based on application requirements is most important. In this article, three electric machine types, axial flux machine, interior permanent magnet (IPM) machine, and switched reluctance machine, are compared systematically to find the best candidate to drive engine accessories in a hybrid truck. These machine types are designed and optimized to meet the application-oriented design requirements and constraints. An extensive Pugh matrix is created where each machine type is scored based on efficiency range, cost, volumetric power density, gravimetric power density, acoustic noise and stress on the rotor, fault tolerance, heat rejection, and manufacturability. Each Pugh matrix component is assigned to a priority-based weighting, based on the application demand, to determine an accumulated score for each machine topology. A full-scale prototype of the best performing machine type is built and tested. Experimental results validate the multiphysics conclusions drawn in the work. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]