Using only the DC current information to detect stator turn faults in automotive claw-pole alternators

The stator turn fault is an important type of fault in automotive claw-pole alternators. In a typical vehicle electric system, however, it is difficult to access the AC current or voltage information of the claw-pole alternator, making conventional sequence-component-based fault detectors useless. This paper analyzes the effects of a full-bridge rectifier on the three-phase unbalanced system. A novel stator turn fault detector was proposed using only the alternator output current measurement. The performance of the stator turn-fault detector is demonstrated both by finite-element simulation and by extensive experimental results. The effect of the winding layout on stator turn fault detection is also discussed. Although the fault detector is originally proposed for claw-pole alternators, it is also applicable to most poly-phase AC generators with a DC link rectifier.