Composite fault-tolerant predictive control strategy for PMSM demagnetization faults

To address the problem of reduced effective flux linkage, degraded dynamic performance, and poor robustness against load variations in permanent magnet synchronous motors (PMSMs) under demagnetization faults, this study presents a composite fault-tolerant predictive control strategy. Firstly, mathematical models of the motor under both normal and demagnetized operating conditions are established. Subsequently, within the deadbeat predictive current control (DPCC) framework, a fast integral terminal sliding mode observer (FITSMO) is designed to enable real-time flux linkage estimation and achieve demagnetization compensation. Simultaneously, to enhance dynamic accuracy and resilience to load disturbances, an adaptive fast terminal sliding mode controller (AFTSMC) and an improved super-twisting algorithm-based load disturbance observer are developed. The observed disturbance values are fed into the speed loop for active compensation. The stability and finite-time convergence of the developed composite fault-tolerant control system incorporating disturbance compensation are proven using Lyapunov theory. Finally, the efficacy of the developed control strategy is validated by experiments. Experimental results demonstrate that the proposed framework has superior fault tolerance, enhanced dynamic response, and significantly improved robustness compared with conventional methods.