Torque and flux estimation for a rail traction system in the presence of intermittent sensor faults

A model based approach to making an induction motor drive tolerant to intermittent disconnections of the current and voltage sensors is considered. Whilst these are abrupt faults they are hard to detect due to their short duration. It is shown that a simple parity equation method is an obvious approach to diagnosing sensor faults, however the application of model based techniques is actually preferable for achieving reliable fault detection and isolation (FDI) when faced with intermittent faults. The induction motor dynamics have a strongly bi-linear structure. A novel bilinear observer is developed, then extended to produce a scheme for detecting and correcting sensor faults.