Diagnosis of broken rotor fault in inverter-fed IM by using analytical signal angular fluctuation

The aim of this paper is to detect broken rotor bar fault at the presence of low frequency load torque oscillation in inverter-fed induction motors. The low frequency load torque oscillation in induction motor may sometimes have the same effect as broken rotor bar fault on the stator current. Especially, when load torque oscillation frequency is close to twice the slip frequency, additional processing need to be done to separate these two effects from each other. To discern these two effects, Analytical Signal Angular Fluctuation (ASAF) spectrum is used. Experimental results are presented for separating broken rotor bar fault from low frequency load torque oscillation.