A Robust Model‐Free Integral Terminal Sliding‐Mode Control Strategy for IPMSM Drives Using a Novel Super‐Twisting Observer

ABSTRACT In this paper, an improved model‐free integral terminal sliding‐mode control strategy based on novel super‐twisting observer (NSTO‐IMFITSMC) is proposed to solve the issues of uncertain disturbances such as parameter disturbances, permanent magnet demagnetization faults, and external disturbances for interior permanent magnet synchronous motor drives. First, a novel extended ultra‐local model is designed, the model dynamic variables are extended into the linear and nonlinear components, and the errors in dynamic variables of the ultra‐local model are reduced. In addition, the speed errors are defined as the system state variables, the finite‐time integral terminal sliding‐mode surface (FTITSMS) is designed, and the performance of the system state convergence is improved. Furthermore, the FTITSMS is combined with the novel super‐twisting algorithm, the NSTO is designed, and the nonlinear components of ultra‐local model are efficiently estimated. The uncertain disturbances of system are compensated in real time, and the performance of anti‐disturbance is improved. Compared with the STO‐MFSMC, the NSTO‐IMFITSMC reduces the speed recovery time by 28.13%, the average torque ripple by 15.22%, and the current total harmonic distortion by 22.45%. Finally, the effectiveness of the NSTO‐IMFITSMC strategy is verified by the simulation and experimental results.