Search

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. [ABSTRACT FROM AUTHOR]

Current control is a common feature in power electronics voltage source converters connected to the grid. In this scenario frequency drifts can entail a big loss in performance of these controllers, significantly worsening the quality of the power delivered to the grid. This article focuses on the study and implementation of current control algorithms for DC-AC voltage source converters (VSCs) that are able of both reducing the harmonic contents of the grid current and maintaining the selectivity of the current control against frequency drifts, so that the stability of the system is preserved. Two types of current control techniques are investigated here, namely, resonant and repetitive controllers. A thorough study of alternative implementation structures is carried out whilst spelling out the frequency-adaptive algorithm in each case. Besides, basic guidelines for their software implementation are given and the computational load for each alternative is analyzed. [ABSTRACT FROM AUTHOR]