Speed Tracking of SPMSM via Super-Twisting Logarithmic Fast Terminal Sliding-Mode Control

This study investigates the speed control of permanent magnet synchronous motors in the presence of external load disturbances via fast terminal sliding-mode control (FTSMC). First, to enhance the speed tracking performance, a logarithmic FTSMC method based on a novel sliding surface is proposed to improve the previously introduced FTSMC. Second, we have derived an enhanced settling time, demonstrating its superiority over that of recently introduced exponential FTSMC through the utilization of a logarithmic sliding surface. Thirdly, the proposed logarithmic FTSMC and exponential FTSMC are compared to demonstrate that the convergence time of the logarithmic FTSMC is less than that of the exponential FTSMC. Finally, super-twisting reaching law is adopted in logarithmic FTSMC to counteract perturbations since it has an ability against various unknown disturbances, such as parameter mismatch, load torque variation, and friction force. Finally, the simulation results show that the proposed strategy can effectively improve the dynamic performance and robustness of permanent magnet synchronous motor systems.