Digital control of a three-phase series-parallel uninterruptible power supply/active filter system

In this paper, a new digital deadbeat controller is designed, implemented, and applied to a three-phase series-parallel line-interactive uninterruptible power supply (UPS). This topology consists of a parallel and a series converter. In this topology, most of the power is supplied directly from the AC line to the load. Therefore, the overall efficiency is higher than that of the on-line UPS. The controller adjusts the current of the parallel converter and voltage of the series converter and follows the reference with two and four sampling periods, respectively. Current and voltage control of the system in different operating modes are discussed. Simulation and experimental results are presented, which show the viability of the proposed controller for this topology.