Low-Cost Online Uninterruptible Power Supply with Input Power Factor Correction and Wide Input Voltage Range

A topology of online uninterruptible power supply (UPS) is proposed. The unique features of developed UPS are: input power factor correction, very wide voltage range (85 - 264 VAC with ability to sustain up to 420 VAC without any damage or fuse opening), galvanic isolation of output (this allows to make common neutral connection). The proposed topology has modified sinewave output voltage and is aimed at low-cost, low-power (up to 150 W) systems. The UPS is built using multiport flyback converter topology, allowing to use only one inductive element in the power circuit. It will start and operate either with or without battery, as well as with shorted battery, thus allowing battery replacement "on-the-fly", without switching off the load. The proposed UPS is primarily for use with remote surveillance cameras, routers, switches, etc.