Robust Output Voltage Tracking Control for Uncertain AC/DC Converter

In this study, a cascade voltage control strategy is proposed for a three-phase AC/DC converter in the presence of parametric uncertainties. The contributions of this article are comprised of two parts. The first one is to devise the inner-loop controller through a simple feedback-linearizing method employing the optimal control gain maximizing the decay ratio of the current tracking error, using the lower and upper bounds of the true parameter value. Moreover, it is shown that the resulting closed-loop system including the first-order internal dynamics is stable. The second one is to investigate that the outer-loop proportional-integral (PI) controller renders the output voltage tracking error dynamics to be asymptotically stable despite the parameter uncertainties, provided that its control gains are chosen to be positive. Simulation results using powerSIM (PSIM) software show that the proposed control scheme provides satisfactory voltage-tracking performance for a wide output voltage operation range.