Model‐Free Fast Integral Terminal Sliding Mode Control Based on Extended Super‐Twisting Sliding Mode Disturbance Observer for PMSM With Unknown Disturbances

ABSTRACT The control performance of a permanent magnet synchronous motor (PMSM) is significantly deteriorated when faced with unknown disturbances, such as model uncertainties, parameter variations, and external interferences. This paper proposes a model‐free fast integral terminal sliding mode control (MFITSMC) approach based on an extended super‐twisting sliding mode disturbance observer (ESTSMDO), referred to as the ESTSMDO‐based MFITSMC approach. First, a unique ultra‐local model (NULM) of the PMSM is developed that accounts for unknown disturbances. Then, the MFITSMC is formulated by integrating a fast integral terminal sliding mode surface with a switching control law. The speed loop controller is designed using the MFITSMC. The ESTSMDO is meant to precisely estimate unknown disturbances and subsequently input them into the MFITSMC controller. The ESTSMDO‐based MFITSMC approach mitigates chattering and improves the system's robustness to unanticipated disturbances. Finally, the simulation and experimental validation demonstrate that the dynamic response of the PMSM system is markedly enhanced, and the chattering associated with SMC is effectively reduced.