Evaluation of the windup effect in a practical PID controller for the speed control of a DC-motor system

Windup effect in a PID controller is the condition of cumulative error in the integral action. It saturates the system actuators, letting the system out of control with a higher controller action. Putting a saturator for the controller action, it is limited into a linear range of operating values. However, it does not eliminate the cumulative error of the integral term. This paper presents the speed control of a motor generator system using a digital PID controller with antiwindup method to eliminate the cumulative error of the integral term of controller action. Initially, a linear model of the motor generator system was identified. From the linear model of the system, a PID controller was designed using pole placement technique. Controller discrete implementation was performed using the backward difference discretization methodology. PID controller consider the antiwindup scheme and its practical implementation employing the Matlab Stateflow toolbox and a data acquisition card. Obtained results showed that the PID controller with antiwindup digital implementation has a good performance against external disturbances and random noise.