Failure analysis of hall-effect sensors in brushless DC starter/generator

Atmospheric corrosion is one of the most common failure phenomena in copper-containing components of areoengine due to corrosive gases and high temperature. This paper described a failure analysis of hall-effect sensors in an areoengine brushless direct-current (BLDC)starter/generator. The failure analysis experiments were performed with electrical performance test, external visual inspection, X-ray inspection, internal visual inspection, scanning electron microscope (SEM)and energy dispersive spectroscopy (EDS). Short-current failure was ascertained as failure mode of the hall-effect sensors by electrical performance test. Internal visual inspection, SEM and EDS were conducted to determine the failure mechanism of the samples as copper sulfide (Cu₂S)corrosion. Moreover, validation experiments were carried out to confirm the results of failure analysis in which the failure of another sample was stimulated under 120 Centigrade for three hours. Some failure causes of the hall-effect sensors were inferred and some recommendations for the optimum design of hall-effect sensor modules were elaborated.