Synthesis of a nonlinear H∞ controller for a three-phase active rectifier

Switch-mode rectifiers have been proved as effective devices to supply steady dc power with improved power quality at ac mains. In this paper, we present a new control scheme, developed under the formulation of nonlinear theory, for three-phase pulsewidth modulation boost rectifiers to achieve unity-power-factor and dc-link voltage regulation with guaranteed robust performance. The closed-loop system is also shown to be Lyapunov stable. The proposed approach provides direct regulation of dc-link voltage with strong robustness against large parameter variations and perturbation in load. The validity of the proposed nonlinear controller is verified by means of computer simulation and experimental analysis.