Online broken rotor bar detection of inverter-fed induction motors operating under arbitrary load conditions

This paper presents a non-parametric approach to failure detection of a broken rotor bar for an inverter-fed induction motors (IM). We lay the mathematical foundation for the concept of a diagnostic model of a rotor bar fault. The diagnostic model captures rotor bar high frequency (HF) characteristics which leads us to a conclusion that the HF equivalent motor resistance can be used as a direct indicator of broken rotor bars. The proposed detection technique is insensitive to other motor parameters and is effective under arbitrary load conditions. The time domain-based signature analysis enables the efficient detection and enhances fault isolation property. The identification scheme was implemented and tested on an inverter-fed 1.5 kW induction motor.