Fixed-time sliding mode observer-based multi-faults estimation method and its application to PMSM drive system

An integral sliding mode observer-based fixed-time multi-faults estimation method is proposed to solve the problem of fast fault estimation for a class of nonlinear systems with multiple types of faults simultaneously. First, a class of nonlinear systems with actuator and sensor faults is considered, and the original system is transformed into two subsystems through coordinate transformation to decouple the actuator and sensor faults. Then, intermediate variables are introduced to transform sensor faults into actuator faults of the augmented systems. For the transformed system, a fixed-time fault observer based on integral sliding mode is designed to realize the fast estimation of unknown terms, and the fixed-time convergence performance is proved. Moreover, based on the output of the fault observer, the actuator and sensor faults in the original system are reconstructed. Finally, the fault model of the permanent magnet synchronous motor is established in the hardware-in-the-loop platform, and the effectiveness of the designed fault estimation method is verified.