Rotor unbalance and broken rotor bar detection in inverter-fed induction motors at start-up and steady-state regimes by high-resolution spectral analysis

• A high-resolution spectral analysis is used for fault identification in an induction motor.
• The methodology uses the Empirical Mode Decomposition and a high-resolution method.
• The methodology could be applied during the start-up transient followed by a steady-state regime.
• The methodology identifies a single broken rotor bar and mixed eccentricity faults.

Fault detection in induction motors operated by inverters is an actual industrial need. Most line-fed machines are being replaced by inverter-fed drives, due to their improved speed regulation, and fast dynamic response, despite the insertion of undesired harmonics. Under this particular operating condition, most of the detection techniques so far developed are unable to distinguish induction motor faults. This paper presents a detection methodology based on the combined use of two techniques: Complete Ensemble Empirical Mode Decomposition and the Multiple Signal Classification. The proposed methodology is applied to an inverter-fed induction motor during a start-up followed by a steady-state regime, where it is verified its capability to identify a single broken rotor bar, mixed eccentricity in the form of motor-load misalignment, and the combination of both faults. From the experimental results, the proposed methodology is proven to be sensitive enough to detect the fault evolution in the time-frequency plane of single and combined faults under different operating regimes (start-up and steady-state) in inverter-fed induction motor.