Detecting and locating the stator turn-to-turn faults in a closed-loop multiplemotor drive system

Multiple motors connected to a single closed-loop inverter drive is a common type of drive topology which has wide application in steel processing industry, electric railway systems and electric vehicles. But condition monitoring for this type of drive configuration remains largely unexplored. This paper proposes a new method not only to detect but also to locate the stator turn-to-turn fault in a multiple-motor drive system. The method achieves very high sensitivity yet remains easy to implement by utilizing the characteristics of current regulators in the motor controller. Experimental results show that the proposed method can reliably detect and locate the stator turn fault on two shaft-coupled 5-hp induction machines under different operating conditions and fault levels with no need of any machine parameters. Although originally developed for multiple-motor drives, the detection scheme can be directly applied to most of conventional closed-loop induction motor drive.