Acoustic Noise Analysis of a High-Speed High-Power Switched Reluctance Machine: Frame Effects

This paper examines the effect of frame on the acoustic noise and vibration of a high-speed and high-power switched reluctance machine (SRM). Five types of frame/ribs are investigated, where different frame thicknesses, types of cooling ribs, and frame shapes have been analyzed. For this purpose, a 12/8 SRM has been designed at 22000 r/min and 150 kW and two stages have been applied. In the first stage, a new equivalent stiffness of the frame is utilized in order to estimate the resonant frequencies for different frame shapes. The paper provides a mathematical calculation method and evaluates its effectiveness with finite-element simulations. The results indicate an improvement between 4 and 25 in the estimation natural frequencies. The second stage includes the vibration and acoustic noise analysis using 3-D finite-element method. Considerations for acoustic noise reduction in high-speed SRM using different frame types and cooling ribs are discussed. Particularly, radial and screw-type configurations represent a better solution to decrease the sound pressure level up to 12dB.