Disturbance observer based multiloop proportional feedback system for output voltage regulation in three phase AC to DC converters

This paper suggests a disturbance observer (DOB)-based offset-free output voltage regulator for the three-phase AC/DC power converters, taking the nonlinearity, parameter, and load uncertainties into account. The proposed multiloop controller is designed in such a way that it feeds back only proportional errors and stabilizes the output voltage and current tracking errors involving the feed-forward compensation terms driven by the DOBs. The DOBs assist the inner and outer loop controllers to ensure the performance recovery and steady-state error rejection properties, which correspond to a major contribution of this article. A three-phase 3-kW AC/DC power converter is used for experimentally verifying the efficacy of the proposed technique.