A new unity power factor telecom rectifier system by an active waveshaping technique

This paper proposes a new three-phase telecom rectifier system in which sinusoidal input current at unity power factor is achieved. Inherent natural wave-shaping capability of the polyphase transformer together with an active current waveshaping technique result in a significant reduction of input and output filter requirements associated with switching ripple and EMI. Further, the proposed scheme is shown to have higher efficiency because it does not employ an intermediate dc-dc conversion stage and has a relatively small number of switches and diodes. The proposed scheme has a regulated and isolated output voltage at low level so that the scheme is suitable for telecom rectifier. The operation principle is described along with a design example and a comparative evaluation. Experimental results on a 1.5 kW prototype are provided to validate the proposed concept.