Adaptive threshold-based fault detection and isolation for automotive electrical systems

In this paper, a fault diagnosis scheme to detect and isolate faults commonly occurring in a vehicle alternator system based on an adaptive thresholds approach is developed. The mathematical model of the alternator subsystem is quite involved and highly nonlinear; to simplify the diagnostic scheme, an equivalent linear time varying model based on the input-output behavior of the system is used for threshold equations derivation. Since the order of the adaptive thresholds obtained for the model is high, two other alternative approximations are investigated. Probability of false alarm in the first approximation is computed. Finally, validity of the proposed diagnosis scheme is tested through simulation and the results are presented.