Angular-based modeling of unbalanced magnetic pull for analyzing the dynamical behavior of a 3-phase induction motor

Abstract

A multiphysics asynchronous electric machine model based on the angular approach is developed in this paper by adding the interaction between the Unbalanced Magnetic Pull and the rotor center radial displacements to reinforce the electro-magneto-mechanic fields couplings. The novelty of the proposed model lies also in calculating the instantaneous angular speed of the shaft and therefore tackling problems in non-stationary operating conditions. This radial force is generated from the magnetic field distortion mainly due to the rotor eccentricity. The shifted rotor geometric center coordinates are introduced to calculate the effective air gap length in the case with eccentricity. The Permeance Network Method is adopted to describe the magnetic field distribution and the electromagnetic force are achieved by applying the virtual work method. This multiphysics model is validated in the quasi-static regime by comparing with the reference data from the traditional numerical model in the case with and without input eccentricity. The physical characteristics about Unbalanced Magnetic Pull and its frequency components are investigated in angular domain to interpret the transfer path from different angularly-periodic variation fields in the induction machine. The impact of the rotor eccentricity amplitude variation on the dynamic behavior of the electric machine are analyzed at different operating points.