NONLINEAR INTEGRAL CONTROL DESIGN FOR DC MOTOR SPEED CONTROL WITH UNKNOWN AND VARIABLE EXTERNAL TORQUE

Abstract

In this work, a nonlinear integral controller is proposed for a Direct Current (DC) motor model in the presence of a variable and unknown external load and for a constant and variable reference velocity. The nonlinear integral term is designed simply by replacing the integral of the error function by the integral of a saturation error function to the error. By adjusting the saturation function parameters the proposed controller will have a robust properties against the uncertainty and the variation of unknown external torque. The numerical simulations explore the ability of the proposed controller in controlling the DC motor speed to a desired value for the constant and variable load and also for sinusoidal desired speed. In addition the results also compared with the classical integral controller to clarify the feature of the present controller.