Z-source online UPS

The online uninterruptible power supply is a double conversion apparatus that provides electricity when the grid fails. Also input power factor correction, output voltage regulation, reduction of total harmonic distortion, electrical isolation and power quality improvement are the main task of online UPS. In conventional UPSs the peak of output voltage is limited to dc link voltage. So, a step up dc-dc converter at dc side or a transformer at ac side is required to provide the boost ability for the UPS. In this paper we introduce a z-source based online UPS with buck-boost ability without the need of aforementioned circuits. Due to this feature, the compensation of power fluctuation can be done in a wider range of input variation. Moreover, due to the lattice network used in this topology, the input power factor is improved. In this paper, the operation principle and design criteria are analyzed. Simulation results show the superiority of the proposed converter.