A High-Efficiency Three-Phase ZVS PWM Converter Utilizing a Positive Double-Star Active Rectifier Stage for Server Power Supply

Disturbance of the climate due to greenhouse gases is the most unsafe and complicated of all the ecological problems. The main cause is the emission of carbon dioxide from fossil fuels, which produces around 80% of the world´s energy. Consequently, energy strategies are mandatory in reducing the total carbon dioxide emanations. At the data centers, one key element that is suitable for energy management is the server´s power supply unit (PSU). The conventional PSU architecture (disregards the power factor correction stage) is based on the conventional low-voltage high-current dc-dc converter which accomplishes the international standards in a range around 1.5 kW. Beyond that power rating, the imposed losses become significantly high. To cope up with the constant increase in information technology demands, this paper proposes a three-phase zero voltage switching dc-dc converter associated with a positive double-star active rectifier and a reduced current unbalance transformer for high-power-density-efficiency energy conversion. The operating stages, topology analysis, and experimental results for a 1.2-kW prototype with 97% efficiency at half power load are presented.