A modified sliding mode speed control scheme for AC servo motor

In this paper, a sliding mode controller (SMC) which can be characterized by high accuracy, fast response and robustness is applied to speed control of an AC-servo motor. The control input is changed to a continuous one in the boundary layer to reduce the chattering phenomenon, and the boundary layer converges to zero when the state variables of the system reach their steady state values. The integral compensator is added to reduce steady state error and to provide the continuous torque reference. The acceleration which is necessary to get the sliding plane is estimated by an observer. The sliding surface is included in the control input to enhance the robustness and transient response without increasing the sliding mode controller gain. The proposed controller is implemented by DSP (digital signal processor). The effectiveness of the proposed control scheme for the speed controller is confirmed through the real-time experimental results in the paper