This paper proposes a three-phase buck-matrix rectifier with series-parallel connected transformers for high power data center power supplies along with parallel connected full-bridge synchronous rectifier circuits in the secondary, to reduce magnetizing current of transformers and current stress in secondary-side FETs. An active regenerative snubber is used to reduce snubber power losses in the secondary side, enabling use of low-voltage FETs, which further reduces the secondary-side conduction loss. Circuit configuration of the proposed converter is presented along with the theoretical discussions and simulation analysis of the parallel-connected rectifier bridges for buck-matrix rectifier. Operation of the proposed converter is demonstrated using a prototype rated for 8 kW, three-phase 400 Vrms AC input and 50 V DC output. Experimental results with maximum power conversion efficiency of 97.7% and 97.3% at rated load are obtained and operating waveforms of the proposed converter are presented.
