This paper proposes a new three-phase diode rectifier system with a sinusoidal input current at unity power factor and a regulated and isolated output voltage at low level. The inherent natural wave-shaping capability of the reduced kVA polyphase transformer together with an active current wave-shaping technique results in a significant reduction of input and output filter requirements associated with switching ripple and EMI. The operation principles are described along with a design example and a comparative evaluation. Experimental results on a 1.5kW prototype are provided to validate the proposed concept.