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Aiming at the problem of severe unbalanced magnetic force (UMF) of the switched reluctance motors (SRMs) caused by eccentricity, this paper analyses the radial electromagnetic force's spatial distribution and frequencies under eccentricity and conduct a compensation method for the UMF. Firstly, the expression of the radial electromagnetic force under eccentricity is derived by using the method of magnetomotive force multiplying permeance, combining with the modification of the permeance. Secondly, the UMF is reduced by applying compensation current to the two stator poles of the permeance-descending phase. The selection of the stator poles and the calculation of the compensation current are decided according to the direction and the value of the unbalanced flux density. Dynamic eccentricity (DE) will produce new frequencies and spatial orders of the radial electromagnetic force, and the static eccentricity (SE) only produces the new spatial orders. The results obtained by the finite element model prove that this method can effectively reduce the UMF without sacrificing the output torque performance. [ABSTRACT FROM AUTHOR]

In this paper, the radial electromagnetic force and vibroacoustic behaviour of a switched reluctance motor (SRM) are predicted and analysed in detail. First, the radial force with the spatial–temporal distribution characteristics is derived analytically and verified by the 2D Fourier transform. Second, a multiphysics model, which not only includes the electromagnetic field, the mechanical field, and the acoustic field, but also takes into account the structural orthotropy and the non-uniformly distributed electromagnetic force, is established to predict the electromagnetic vibration and noise of a SRM. Third, based on the spatial and temporal orders of the force harmonics, the vibroacoustic mechanism of a SRM is revealed. Finally, the electromagnetic force and vibration under two control strategies, which include the angle position control (APC) and the current chopping control (CCC), are compared and analysed, respectively. The results show that the electromagnetic vibration and noise of a three-phase 12/8 SRM are mainly caused by the force harmonics with the spatial order of 4 and the temporal orders of 3 N 0 ± 1 (N 0 = 0, 1, 2···). Besides, under the two control strategies, the orders of the electromagnetic force and vibration are the same, but the amplitudes are different. [ABSTRACT FROM AUTHOR]