Finite-Time Output Feedback Control for PWM-Based DC-DC Buck Power Converters of Current Sensorless Mode

This paper investigates the finite-time output feedback control problem for dc-dc buck switched power converters of the current sensorless mode. A finite-time state-feedback controller is first built by using a recursive design method, and then a novel reduced-order observer, rather than the conventional full-order observer, is derived to estimate the unmeasurable state of the dc-dc buck system with a finite-time convergence rate. The output feedback control law built by combining the state-feedback control law and the measured system state from the observer is proved to be effective with an explicit stability analysis. Compared with the asymptotic stability control method, not only a faster convergence rate around the equilibrium is obtained but also a better suppression ability against resistance, inductance, and input voltage variation can be achieved for the closed-loop system. Moreover, the sensorless control strategy will be more reliable and cost reducible than its state-feedback control counter-case. Simulations and experimental comparison results verify the effectiveness of the proposed control method.