FO improved fast terminal sliding mode control method for permanent‐magnet synchronous motor with FO disturbance observer

Abstract

This study proposes a fractional-order (FO) improved fast terminal sliding mode controller for permanent-magnet synchronous motor speed regulation system. By designing an FO proportional-integral controller for current loops, an FO model between reference q -axis current and speed output is proposed. By introducing an FO terminal sliding mode surface, a novel FO terminal sliding mode controller is designed for speed loop to improve the speed tracking performance. The proposed FO controller can make speed reach reference value in finite time. Moreover, it is proved that the control time of the FO sliding mode controller is shorter than integer-order (IO) sliding mode controller. To further enhance the convergence speed, the fast terminal sliding mode control method is used. Meanwhile, FO disturbance observer is utilised to enhance the disturbance-rejection ability. The control law of the proposed controller is designed according to Lyapunov stability theorem. Finally, Simulation and experimental results demonstrate the effectiveness, high control performance and high disturbance-rejection ability of the proposed composite FO controller in comparison with IO controller.