Diagnosis of Induction Machines'Rotor Faults in Time-Varying Conditions

Motor current signature analysis (MCSA) is the reference method for the diagnosis of rotor faults of induction machines, however in time-varying conditions it fails as slip and speed vary and thus the sideband components are spread in a bandwidth proportional to the variation. Such applications are common in the aerospace, appliance, railways, and automotive industries and also in electric generators for wind turbines. In this paper a simple and effective method is presented that allows the diagnosis of rotor faults for induction machine drives in time-varying conditions. It is tailored for a specific railway application where the control system provides suitable signals that are exploited for the demodulation to a constant frequency of time-varying signatures related to the rotor faults. Simulations and experiments are reported to validate the proposed method on a critical speed transient.