I. Introduction
The squirrel cage induction motor is ubiquitous in many industrial applications. The identification of the failure of the motor in an early stage is important to improve production and minimize the damage [1], [2]. A considerable number of researchers are interested in the monitoring of induction motors and detection of broken bars [3]– [11]. It is known that the rotor bar defect, even with a small crack causes a redistribution of rotor currents, and the increase of current in adjacent bars degrades the performance and reliability of the motor [12].