Single-phase multi-source on-line UPS with isolated battery charger

Uninterruptible Power Supplies (UPSs) are used to supply a wide variety of critical loads in situations of power outage or unexpected voltage fluctuations. Various UPS topologies provide different level of power quality to the critical load. On-line topology provides the best protection, and it is often the preferred choice for larger UPS installations. This paper presents a single-phase multi-source on-line UPS with isolated battery charger. The proposed structure consists of a boost rectifier, an inverter, and Bidirectional battery charger that is integrated with a Photovoltaic (PV) system. In conventional UPS systems, the battery is charged during normal operation from the grid and discharged to supply the loads during emergency conditions. Operation of grid and PV system as sources in parallel, utilizes the energy that the PV offers, solves PV system fluctuations, and increases the overall accessibility. Furthermore, the performance of UPS is improved by the switching rectifier in the grid side. Isolation would increase UPS flexibility and ensures compatibility with the required safety issues. The basic principles of the developed system and control algorithms are discussed in detail. Performance of the proposed structure is analysed and confirmed using simulations in MATLAB/Simulink software.