Uninterruptible Power Supply (UPS) using high frequency transformer

Abstract

Uninterruptible power supplies (UPS) design with low frequency transformers for isolation purposes are known to contribute to their bulkiness in terms of size and weight. A UPS with high frequency isolation transformer has been proposed in literature to overcome the problems related to the use of the low frequency transformers. This research involves a simulation study on a single-phase UPS system with design that includes a high frequency isolation transformer. With the use of a high frequency ferrite transformer for instance the UPS system can be made smaller and lighter. There are a few stages of the system that need to be considered in the simulation study. This includes a rectifier and inverters with high switching frequency and at line frequency respectively. The high switching frequency inverter is linked directly to the high frequency transformer. The UPS has been designed to eliminate harmonic currents while realizing isolation between the AC input and DC output power stage as well as matching the DC voltage of the PWM inverter by means of integrating a compact high frequency transformer into high-frequency transitional state. The results of the simulation study however are not as expected at all stages of the system.