Digital Control of Three-Phase Series-Parallel Uninterruptible Power Supply Systems

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 kind of UPS system provides input power factor correction, output voltage conditioning, and high efficiency. The objective of the controller is to achieve deadbeat dynamic response for the parallel and series converters. The proposed controller adjusts the current of the parallel converter and voltage of the series converter with two and four sampling periods, respectively. A reduced-parts topology is also introduced that has less number of power electronics components as well as switching functions. The power flow of the system in the presence of current and voltage harmonics is discussed. Simulation and experimental results are presented, which show the viability of the proposed controller for this topology.