Keywords: adaptive filters, digital deadbeat controllers, UPS, uninterruptible power supply, reference waveform generators, power electronics, parallel converters, series converters, simulation
A three-phase uninterruptible power supply with an adaptive reference waveform generator
In this paper, a new digital deadbeat controller along with a modified adaptive reference signal generator are 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 with higher efficiency compared with other kinds of UPS. It consists of a series and a parallel converter. The series converter deals with voltage-based distortions while the parallel converter cancels the current-based disturbances. The objective of the controller is to achieve deadbeat dynamic response for the parallel and series converters. The adaptive filter provides the reference signal for the load voltage and source current without any phase shift. The proposed controller adjusts the current of the parallel converter and voltage of the series converter with two and four sampling periods, respectively. Simulation and experimental results are presented, which show the viability of the proposed controller and reference signal generator for this topology.