An integrated flyback converter performing the combined functions of uninterruptible power supply (UPS) and switch-mode power supply (SIMPS) is presented. This converter has a high voltage main power input and a low voltage backup battery input, DC output is obtained from the main input via a flyback converter during normal operation and from the backup battery via another flyback converter when input power fails, High conversion efficiency is achieved in normal, backup, and charging modes as there is only a single de-de conversion in each mode, The converter circuit is very simple, with two switching transistors, a relay for mode switching, and a single magnetic structure only, This new design offers substantial improvement in efficiency, size, and cost over the conventional cascade of UPS and SMPS due to single voltage conversion, high frequency switching, and removal of design redundancy, The operation, design, analysis, and experimental results of the converter are presented.
