Design of fault-tolerant observer for brushless DC motor under rotor eccentricity fault

The traditional sliding mode observer (SMO) cannot accurately observe the back-electromotive force (back-EMF) values when the brushless DC motor (BLDCM) has rotor eccentricity fault. In order to solve the problem, the influence of static eccentricity fault on inductance and back-EMF is analysed, and a fault-tolerant observer is designed in this paper. The fault-tolerant observer uses the Lyapunov stability theory to identify the phase-to-phase inductance parameters online, and is based on the traditional SMO. According to the phase-to-phase inductance identification values, the SMO coefficient matrix is adjusted in real time. Simulation results show that the designed fault-tolerant observer can accurately observe the phase-to-phase back-EMF values of BLDCM under the rotor eccentricity fault condition.