Discrete-time robust voltage controller for buck converters based on the coefficient ratio method with open-loop feed-forward control

Abstract

In this study, a hybrid controller based on the discrete-time characteristic ratio controller and an open-loop feed-forward controller is presented for voltage control of the buck converters used in many different applications. The presented controller is designed using a standard-form characteristic ratio. The designed controller is supported by the open-loop duty ratio as a feed-forward term to improve its robustness against the disturbance, especially to changes in the input voltage. The performance of the designed controller to follow the change in the output-voltage reference is investigated by simulation and real-time experimental studies. By designing the presented controller for three different generalized time-constants, it has been validated that the transient regime of the closed-loop system can be adjusted without disrupting the general wave structure of the system response. The robustness of the designed controller for various disturbances such as the input-voltage and load variations and parameter uncertainties has also been thoroughly investigated. The results of comparative simulation and real-time experimental studies realized by the PID and CR method without FF term clearly demonstrated the superiority of the presented method.