Isolation of Induction Motor Rotor Fault Signatures by Stray Magnetic Flux and Torque Monitoring

Induction motors are the most established machines in the modern industry as they are broadly deployed in a variety of applications spanning several technologies in electrification, traction, and renewable energy. As such, grid-fed as well as inverter-fed induction machine applications are becoming more and more widespread. Therefore, to avoid failures caused by adverse conditions such as stresses and faults, the development of fault detection frameworks is of the uttermost urgency. This paper presents a new diagnostic technique based on torque monitoring for rotor bar faults in squirrel-cage induction motors. The proposed method is based on the isolation of harmonics during the steady-state operation of the machine by the application of a rigorous signal estimation algorithm that enables the reliable tracking of fault-related signatures in the machine's stray flux and torque signals. The application of the method is demonstrated using data from extensive finite element simulations for various bar breakage scenarios. The simulation results and experimental results indicate that the method is versatile in terms of machine geometry and power rating.