Abstract: The traditional controller has many problems. For instance, the speed overshoot is over the given range. Another problem could be the anti-disturbance capability is not enough. This research added the real variable function based on the exponential approach law. It proposed a fractional exponential reaching law SMC system with better adaptive ability. In addition, simulation experiments have been conducted in MATLAB/Simulink. This paper compared the proposed control system, the traditional PI control system, and the exponential reaching law SMC system. The result shows that the controller with the fractional exponential approach law has better control ability of the speed loop. Moreover,it reduces the torque ripple of the electric motor and promotes the immunity of the speed governing system. The new design could help keep the stability, reduce the energy consumption of the electric motor, and increase energy efficiency.

    Key words: exponential reaching law; permanent magnet synchronous motor; sliding mode control system; energy consumption