Development of a high efficiency UPS having active filter ability composed of a three arms bridge

This paper describes a newly developed high-efficiency uninterruptible power supply (UPS) having an active filtering ability which is composed of a three arm bridge. The developed single-phase UPS, of rating 3 kW and 100, V has the following three abilities: (1) in normal operation, the UPS works as an active filter by using two arms and not only eliminates harmful harmonics created by nonlinear loads, but can also realize high efficiency; (2) the three-arm bridge converter/inverter can compensate any change in input supply voltage acting like a voltage regulator; and (3) at the power-off state, one arm works its a chopper to maintain constant DC link voltage and other two arms work as a bridge inverter. As a result, the developed UPS is achieved with an input power factor of 99% and an efficiency of over 95% in active filter operation and also a output voltage distortion of under 2% in converter/inverter operation