On Shortening the Numerical Transient in Time-Stepping Finite Element Analysis of Induction Motors Under Static and Dynamic Eccentricity Faults

Abstract

Modeling induction motors under static and dynamic eccentricity faults, arising from bearing wear and tear, through Time-Stepping Finite Element (TSFE) methods suffers from the resulting long numerical transient response before numerical convergence is achieved. In this paper, this lengthy transient phenomenon is substantially reduced through the so-called Virtual Blocked Rotor (VBR) approach implemented here. This approach starts with an initial calculation of the motor permeabilities and skin effect corresponding to the operating condition of the induction motor. Such calculations are performed in an FE Eddy-Current frequency-domain solver reflecting the voltage supply magnitude, value of slip, type and degree of eccentricity fault. The calculated permeabilities are imported into the TSFE simulation of the faulty induction motor and the performance characteristics of the faulty motor are extracted for further analysis. In this paper, static and dynamic eccentricities are applied to the induction motor under study. It is observed here that this approach successfully solves the problem of a lengthy numerical transient response and saves computational time in the analysis process.