Research Of Low Voltage/High Current Output DC/DC Converter Based On Synchronous Rectification Technology

With the rapid development of Information Technology, low power DC/DC converter is used widely in computer and communication applications. In order to meet demands for faster and more efficient data processing in these applications, it will require aggressive power management. That is to say, it will require special power supply to provide lower voltages with higher currents and fast transient capabilities, whilst high power density, high efficiency, and high reliability is also desired.This work presents some research on the corresponding problem of high efficiency low-voltage/high-current output DC/DC converter. The principles and characteristics of Synchronous Rectification(SR) are given, and advantages of Self-Driven SR in low power applications is detailed. Review of several topologies which incorporate Self-Driven SR makes the constrains of conventional Self-Driven SR scheme apparent and thus a new scheme to drive SRs is proposed.The developed Single-Winding Self-Driven Synchronous Rectification(SWSDSR) scheme works properly in topologies that drive symmetrically the transformer (push-pull, half bridge,...).It allows for maintaining the SRs on even when the voltage in the transformer is zero, which is impossible to do in traditional self-driven approaches. Furthermore, driving losses are very low, since the discharge of one MOSFET is used to charge the other and vice versa. Influence of coupling between transformer windings on the performance of this circuit is analyzed in detail and different winding design is compared.In this paper, the DC operation principle of SWSDSR half-bridge is analyzed. And power loss analysis of SRs and the layout design related to SRs are very important to the proper design. With a small signal mathematic model of half-bridge converter, the relationship between performance of power supply and frequency domain characteristics of the system is analyzed. Based on the above study and some simulation the system design is completed.In the end, a prototype is fulfilled , and experimental results verify the analysis and design in this work. Some suggestion is put forward for further research work.