Radial force calculation and acoustic noise prediction in switched reluctance machines

This paper presents an analytical method for calculating the radial force a nd predicting the acoustic noise in switched reluctance machines (SRMs), Th e main source of acoustic noise in an SRM is the radial magnetic force indu cing resonant vibration with circumferential mode shapes of the stator, An analytical relationship between radial force and radial vibration is determ ined, which can be used to predict the noise power level at the frequency o f operation, The vibration and sound are functions of machine dimensions, m aterial properties, and rotational speed. The knowledge of the circumferent ial mode shapes of vibration, the natural mode frequencies of the stator, a nd the frequency spectrum of the radial magnetic force can be effectively u tilized to design SRMs with minimal noise through geometrical design variat ions. The effect of the number of stator and rotor poles on acoustic noise can also be analyzed with the model presented in this paper. Magnetodynamic simulation by finite-element analysis software has also been carried out t o verify the calculation of radial force using the proposed analytical mode l.