Design of a Robust Controller for a Voltage-mode Controlled Buck Converter

Linear controller-based voltage-mode control finds widespread application in the power management industry due to its ease of control. A linear controller is designed based on the average small-signal model of the converter which ignores the effect of converter's parasitics, dead-time, etc. Thus, the designed linear controller often fails to provide desired transient and steady-state performances in a practical converter. In this paper, a robust controller is designed using the average small-signal model of the synchronous buck converter. The designed robust controller can handle the impact of the system parasitics and dead-time. The performance of the proposed robust controller is compared with a linear controller using a MATLAB/Simulink model of the synchronous buck converter. Simulation results show significant improvement in the output voltage overshoot and undershoot and settling time when the robust controller is employed in the closed-loop.