Study Of A Current-feed Single-switch Forward Resonant DC Transformer(DCX)Primary Diode-clamping

With the development of technology,the power supply systems of data centers and communication base stations have undergone tremendous changes in the past two decades from centralized power supply systems to distributed power supply architectures to intermediate bus architectures.The intermediate bus power supply architecture is more and more widely used due to its low cost,high reliability,easy to upgrade and update.According to the research,the current industry for the low power(less than 150W)communication equipment power supply scheme,usually using the first level of the non-adjustable intermediate bus converter(Bus Converter or DCX).Since most of the load power has to undergo this level of conversion,its efficiency requirements are high.In the case of low frequency,the phase-shifted full-bridge topology is widely used in busbar converters due to its simple structure and easy implementation of zero-voltage switching of the switching transistor.As people’s requirements for power density continue to increase,when the switching frequency of the converter is increased to the megahertz level,the phase-shifted full-bridge topology cannot be realized due to the soft switching of the secondary-side synchronous rectifier,resulting in large reverse recovery loss and high voltage stress.Meet high density and high efficiency requirements.The resonant topology exhibits good efficiency characteristics at high frequencies because it enables soft switching of all semiconductor devices.Traditional half-bridge or full-bridge resonant topologies use two or four switching transistors.For low-power communication and information equipment applications,this multi-switch has a high topology cost.Due to its quasi-soft switching characteristics,the single-tube resonant topology can replace the LLC topology in low-power applications,and the single-tube topology uses only one switching transistor,which saves cost compared to the traditional half-bridge resonant topologyAiming at the problem of excessive voltage stress at the primary side of the existing single-tube resonant topology,a single-tube forward-synchronous resonant topology of the transformer primary clamp is proposed.The method of adding a winding and a diode to the primary side of the transformer is proposed.The voltage across the main switch is clamped to twice the input voltage,which greatly reduces the voltage stress of the switch.While taking into account the advantages of simple single-tube resonance topology,convenient driving,and small number of switching tubes,the primary switching tube can select a switching tube with lower withstand voltage,reduce the conduction loss of the switching tube,and improve the efficiency.In this paper,the working mode is analyzed,the design process of key parameters is given,and the prototype is designed for the application of power supply for large-scale communication satellite communication equipment.The theoretical analysis is verified by experiments.