Series-Parallel Active Filter/Uninterruptible Power Supply System

In this article, a novel series-parallel active filter/uninterruptible power supply (UPS) system is presented. Modeling and analysis of the newly introduced series-parallel UPS topology, along with the three-phase unified power quality conditioner (UPQC), are presented. Similarities and differences of these two topologies in different operating modes are explained. New current and voltage control methods for these systems are described and block diagrams are presented. The power flow in the UPQC and UPS systems and power of each converter are investigated. New term of characteristic power is defined to evaluate the power flow in the presence of harmonics. Simulation and experimental results of both systems are also presented to verify the analysis.