On-line detection of stator winding short-circuit faults in a PM machine using HF signal injection

This paper presents a high frequency (HF) injection scheme to detect short-circuits faults in the stator winding of a VSI-fed permanent magnet (PM) machine. The proposed approach is derived from sensorless control schemes based on HF voltage signal injection for tracking position in a surface-mount PM machine. In this paper the method of space-modulation profiling (SMP) is used to obtain a magnetic signature of the machine operating under healthy conditions. This signature can then be compared with the on-line measured saliency profile during normal operation to detect any abnormality in the drive´s performance. The main application of the presented scheme is for the detection of windings problems such as insulation breakdowns and short circuits. Experimental results are shown for the case of a PM servo drive where incipient and full short-circuit faults have been emulated and successfully detected. Due to its relatively simple implementation and since no additional transducers are required, this approach presents an interesting alternative for condition monitoring.