Analysis of electromagnetic stiffness in submersible motors with inclined rotor eccentricity

The electromagnetic stiffness is an important parameter in electromechanical coupling system, and it depends on whether there is eccentricity in motor air-gap. In this paper, the electromagnetic stiffness is proposed. The slipping surface technique is cited. The submersible motors with inclined rotor is applied, and the influence of eccentricity rotor on electromagnetic stiffness is calculated theoretically and compared by finite element simulation, based on which the calculation modeling of electromagnetic stiffness is built. Furthermore the distribution of magnetic field energy as well as electromagnetic stiffness along the machine axis, in the submersible motors with inclined rotor, is obtained. The variation of magnetic field energy with eccentricity angle reflecting eccentricity level, and the relationship between electromagnetic stiffness and inclined angle alpha, are obtained respectively. Finally the reliability of model by comparing the simulation results with numerical analysis is presented. The investigation in this paper supports references in the eccentricity fault diagnosis for submersible motors and theoretical basis for study of rotor dynamics.