Impact of closed-loop control on behavior of inverter-fed induction motors with rotor broken-bars fault

This paper studies rotor broken bars fault in induction motors and proposes its fundamental concept. This concept is used to obtain the imposed frequencies on the faulted induction motor variables analytically. It is also shown that the fault-dependant frequencies are present in the output voltage of the inverter-fed motor utilizing the transfer function of the speed control loop. Some additional frequency patterns, other than that of the line-start motor, influence the inverter-fed motors performance and this causes more distortions and larger index value compared to the line-start case. The aforementioned analytical approach is validated by experiments.