Analysis of rotor faults in three-phase induction machines.

摘要

The detection of rotor faults in three-phase induction machines by means of current signature analysis has been performed by harmonic analysis and neural network analysis. The types of rotor faults considered here are broken rotor bars and static eccentricity. Detailed simulation of induction machines with rotor faults has been performed by finite-element analysis, space-harmonics analysis, and transient analysis. This thesis uses the method of transient analysis to simulate the performance of induction machines under these conditions. What distinguishes this work from previous efforts is the derivation of transient expressions for all self- and mutual-inductances between individual stator coils and rotor bar loops. While many authorities have performed similar calculations, detailed expressions for the inductances under all degrees of rotation have not been presented. This detailed modeling allows for greater precision in identifying the magnitude and frequency of the current harmonics present under fault conditions. The simulation was performed using a computer program written specifically for this project. The output of the program is a table of current values at each step of the simulation. This output was further analyzed using the Fast Fourier Transform (FFT). The results of this analysis are in agreement with results presented in the literature both in analytical and experimental studies.