Finite Element Analysis of Motor Eccentric Forces and Effects on Vibration

Abstract

Machinery trains with motor drives are widely used in industry. Motor related forces may become one of the sources of machinery vibrations. Motor eccentricity is one of the common phenomena that cause forces exerted on motor and the machinery train. The eccentricity between stator and rotor is almost inevitable. Mass unbalance, shaft bending as well as bearing tolerances can introduce the eccentricity. Moreover, modern machines are being designed for higher performance, which often cause significant nonlinear effects. Therefore, a more complete picture of the nonlinear dynamic characteristics brought by motor eccentricity is required to enhance machinery train design, refinement, monitoring and maintenance. The purpose of the work has been to develop accurate modeling methods of electromagnetic forces, especially at static eccentricity fault, and to study the force effects on driven machinery vibrations. This research work focuses on the characterization of the eccentric forces and their effects of the rotor eccentricity fault on vibration. The most accurate numerical method of finite element method is adopted for field analysis in calculation of characteristics including air gap flux density, eccentric force and torques. An improved movement modeling technique is proposed and developed into the finite element analysis of electric machines.