A new method to detect stator turn-to-turn faults in a closed-loop multiple-motor 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 to detect the stator turn-to-turn fault in a multiple-motor drive system. The method achieves very high detecting sensitivity yet remains easy to implement by utilizing the characteristics of current regulators in the motor controller. Experimental results show that the method can reliably detect a short circuit of 1 turn out of 216 turns per phase on two 5-hp, shaft-coupled induction machines. Although originally developed for multiple-motor drives, the detection scheme can be directly applied to most of normal closed-loop induction motor drive.