Performance investigation of a three-phase three-wire series-parallel compensated line-interactive UPS system based on SVPWNI and controlled by two digital signal processors

A three-phase three-wire series-parallel compensated line-interactive UPS system based on space vector PWM and controlled by two individual digital signal processors is proposed in this paper. A series voltage-source converter works as sinusoidal current source in phase with the corresponding utility voltage to make power factor unity, while a parallel voltage-source converter is controlled as constant-voltage constant-frequency sinusoidal voltage source tracking the phase of utility voltage also. Therefore, this kind of UPS system has the capability of universal line-power filtering, which can suppress the voltage harmonic at the utility and the current harmonic deriving from non-linear load. In addition, the proposed system can compensate reactive power simultaneously. A 10 kVA prototype was established and tested in detail in the case of three different typical loads. The theory analyses are verified by abundant experimental results.