A front-end DC/DC converter for network server applications

Network server power supplies call for a dual universal AC line input and 48V DC input front-end converters to generate the 380 V DC bus. To realize the DC input front-ends, nonisolation DC/DC power converters, such as continuous current mode (CCM) boost converters, are not good candidates because of their power limitations under extreme duty cycles. Cascade DC/DC power converters can meet this specific application requirement with the deficiency of extra complexity and higher cost. Although coupled inductor DC/DC converters can provide high step-up voltage gain without the penalty of extreme duty ratio, their efficiency is poor due to the losses associated with the leakage inductors. In this paper, a clamp mode coupled inductor boost converter with no extreme duty ratio is presented. The proposed topology utilizes coupled inductor to achieve high step-up gain as well as to alleviate the output rectifier reverse recovery problem. The efficiency of a 1 kW prototype is higher than 90% under nominal operation condition.