Series-Parallel Compensated UPS With Double Converters

A three-phase series-parallel compensated line-interactive UPS system is studied in thisthesis. The three-phase series-parallel compensated line-interactive UPS system is composedof a series three-phase converter and a parallel three-phase converter. Analysis, simulationsand experiments are centered around how to control the series three-phase converter as asinusoidal current source and to control the parallel three-phase converter as a sinusoidalvoltage source. Mathematical models of the series three-phase converter and the parallel three-phaseconverter in three phase stationary coordinate, two-phase stationary coordinate and two-phaserotating coordinate are established in this thesis. With the introduction of the concept ofvoltage space vector and coordinate transformations, and easy to let three-phase systemtransform between the different coordinates. In this thesis, for the series three-phase converter, direct current control scheme areselected; while for the parallel three-phase converter, based on the multiple-loop of voltageand current control scheme, we introduce the repetitive control scheme. In experiments, wecompare the combined control scheme of multiple-loop of voltage and repetitive control withmultiple of voltage and current control scheme. The combined control scheme proved to behighly effective at the parallel three converter's output no matter what kinde of loads areconnected. The compensation characteristic and power flow of three-phase series-parallelcompensated line-interactive UPS system is analyzed in this thesis. After the whole systemstart, it can work as UPQC without storage battery. A 20kVA three-phase series-parallel compensated line-interactive UPS system based onDSP controller is designed in this thesis. DSP chip TMS320F240 has very rich controllerperipherals and hence to create an ideal solution for this kind of UPS system. The experimental results are given when utility voltage over 15%, in the normal valueand under 15%. General analysis of the experimental results is given in this thesis too.