Resonant-repetitive controller with phase correction applied to uninterruptible power supplies

This paper proposes a new control structure based on the parallel interconnection of a filtered repetitive controller and a resonant structure applied to uninterruptible power supplies - UPS. In particular, the filter in series with the repetitive controller adjusts the phase angle between resonant and repetitive loops, improving in this way the tracking performance. A particular filter structure is proposed, and an augmented state formulation is derived. Controller design is then carried out by the solution of an optimization problem with linear matrix inequalities constraints. Experimental results on a commercial 3.5kVA UPS illustrate the closed-loop performance.