A Stator Turn Fault Tolerant Strategy for Induction Motor Drives in Safety Critical Applications

A turn fault in the stator windings of an induction motor (IM) causes a large circulating current to flow in the shorted turns and generates excessive heat. Without limiting the heat, which is proportional to the square of the circulating current, the fault generally develops into catastrophic phase. In this paper, it is shown that the circulating current in the shorted turns is strongly related to the stator line-neutral voltage. Also, it is observed that with an appropriate adjustment to the rotating magnetic flux, the stator line-neutral voltage can be reduced, resulting in a significant reduction in the circulating current. Based on these principles, a stator turn fault tolerant strategy for IM drives is proposed. This strategy does not require any change in the standard drive configuration and most importantly, does not result in the complete loss of availability of an IM drive in the presence of a stator turn fault. Simulation and experimental results are provided to validate the proposed strategy