Single-Stage Three-Phase Buck-Matrix Rectifier with Series-Parallel Connected Transformers for High-Power 48 V Data Center Power Supplies

This paper proposes a single-stage three-phase buck-matrix rectifier for high power data center power supplies. The proposed converter is composed with series-parallel connected transformers to reduce magnetizing current and current stress in synchronous rectifier FETs. An active regenerative snubber is used to reduce snubber power losses and voltage oscillation in synchronous rectifier FETs, enabling use of low-voltage FETs, which further reduces the conduction loss. In addition, the proposed converter realizes ZVS operation with single-stage power conversion. Circuit configuration and features of the proposed converter are presented along with theoretical discussions and simulation analysis of the parallel-connected rectifier bridges. 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 show that the proposed converter can realize unity power factor and THD of 4.7% at rated power, achieving a maximum power conversion efficiency of 97.7% and a rated power conversion efficiency of 97.3%.