本科毕业设计（论文）-基于同步整流技术的低压大电流输出直直变化器的研究.doc

本科毕业设计（论文） 基于同步整流技术的低压大电流输出直直变化器的研究 *** 燕 山 大 学 2012年6月  摘 要 随着互联网技术、微电子技术和信息技术的迅速发展，IC芯片和DSP（数字信号处理器）的普及应用，小功率DC/DC变换器在计算机、通讯等应用场合得到了广泛的使用。为了满足这些场合对更快、更有效的数据处理的要求，其供电电源的要求也在不断提高，具体表现在:更低输出电压、更高输出电流、高功率密度、高效率、快动态响应及高可靠性。 本文针对低压/大电流输出的小功率DC/DC变换器，围绕着变换器的效率问题，分析了同步整流的原理和特点，重点阐述了自驱动同步整流在低功率场合的优势，在分析比较了多种与自驱动同步整流相结合使用的电路拓扑后，指出常规的自驱动同步整流方案限制了与之结合使用的电路拓扑的范围这一局限性，从而给出了一种新的单绕组自驱动同步整流方案。 这种新的驱动方案简单、经济、可靠，非常适合在低功率的低压/大电流输出DC/DC变换器应用场合使用，且拓宽了自驱动同步整流的应用拓扑范围，特别适用于宽输入电压范围、变压器对称工作的拓扑(如推挽、桥式等)。 本文重点是对单绕组自驱动同步整流对称半桥变换器进行了分析研究，得到一种新的单绕组自驱动控制驱动方法，通过对电路元件参数的计算和选择，设计出了主电路和驱动电路，并通过PSpice软件对其进行了仿真。 关键词 直-直；变换器；小功率；同步整流；单绕组自驱动；对称半桥；系统设计；控制 Abstract 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 SR on even when the voltage in the transformer is zero, which is impossible to do in traditional self-driven approaches. This article focuses on the analysis of single-winding self-driven synchro