Performance Comparison of Sliding Mode Control and Conventional PI Controller for Speed Control of Separately Excited Direct Current Motors

Abstract

Direct Current (DC) motors have been used extensively in industry mainly because of the simple strategies required to achieve good performance in speed or position control applications. This paper addresses controlling of speed of a separately excited DC motor which remains among the vital issues. A separately excited DC motor is generally controlled by Proportional plus Integral (PI) controller. PI controller is simple but sensitive to parameter variations and external disturbance. Due to the robustness of Sliding Mode Control (SMC), especially against parameters variations and external disturbances, and also its ability in controlling linear and nonlinear systems; a separately excited DC motor sliding mode speed controller technique is proposed in this paper. Performance of these controllers has been verified through simulation results using MATLAB/SIMULINK software. The simulation results showed that SMC was a superior controller than PI controller for speed control of a separately excited DC motor.