Fixed-time non-singular terminal sliding mode control for PMSM drive systems

To further improve the response speed and anti-interference capability of permanent magnet synchronous motors (PMSMs), many advanced control algorithms have been developed. Among the various advanced controls, the fixed-time terminal sliding mode control is one of the effective methods. However, there are still some problems, e.g., too many parameters imposed on the control design in the existing results. In this paper, a fixed-time non-singular terminal sliding mode control (FTNTSMC) method is proposed for the speed loop of a PMSM drive system. First, to improve the closed-loop performance of the PMSM drive system, the relationship between the reference q-axis current and the speed of the PMSM is described in a second-order model. Next, a sliding mode surface with variable exponential coefficients is selected, and the expression of the controller is given. Then, the stability of the PMSM drive system is demonstrated by using Lyapunov functions. Using this method, the fixed-time convergence of the PMSM drive system can be realized and the occurrence of singularity phenomena can be avoided in a simpler and easier method. Finally, the effectiveness of the proposed method is verified by simulation and experimental results.