Abstract:
Uninterruptible power supply (UPS) provides environment-friendly, efficient, reliable electricity under all conditions of the grid. The efficiency of the UPS is the main concern due to its long operation. To overcome the aforementioned problems, a two-stage isolated online-UPS using Z-source Inverter is proposed for high power applications. The proposed online-UPS consists of only two power stages i.e. AC-DC Converter and Z-Source inverter. In the first stage, the AC-DC converter operates in continuous conduction mode (CCM), with minimum utilization of semi-conductors and uses a high-frequency transformer for isolation. The second stage performs DC-AC conversion through the ZSI topology instead of traditional inverters. ZSI circuitry is coupled with the symmetrical LC network, thus UPS maintains the desired AC voltages regardless of the change of voltage at the terminal of the battery. Battery bank in the proposed system is arranged in parallel and operates at a low voltage. The reliability of the system is too much higher than conventional UPS system due to the path for the flow of current is more than one more. The investigating system increases the overall efficiency, reliability, cost effectiveness of the system and reduces weight, semi-conductor utilization with minimum loses. To validate the performance and effectiveness of the proposed system, Simulations have been carried out in MATLAB/Simulink real-time environment. The simulation results verified that the proposed system is more efficient as compared to conventional Online UPS systems
