有源钳位正激软开关变换器设计研究

发布时间：2018-02-27 13:02

本文关键词： 正激变换器有源钳位软开关同步整流　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着现代电子产品的体积不断减小，对效率的要求越来越高，开关电源也在向高功率密度、高效率、重量轻体积小和绿色化等方向发展，软开关技术和同步整流技术为开关电源往这个方向上发展提供了重要的技术支持，也在电源领域扮演着重要的角色。本文选取具有同步整流的有源钳位正激式拓扑，利用有源钳位技术使开关管达到零电压开通和关断的软开关效果，变换器工作占空比可以大于50%，利用钳位电路能有效实现磁复位，，并且使主、辅开关管达到零电压开通和关断，减小开关引起的电压电流尖峰和开关损耗；采用同步整流管代替普通整流二极管，并利用软开关技术能进一步减小导通损耗，提高效率。首先讨论了正激变换器几种磁复位技术的优缺点，分析了同步整流技术的原理，对低边钳位和高边钳位两种拓扑进行对比分析，给出选择依据，重点分析了拓扑结构在一个开关周期中分为12个阶段下的运行原理，并给出实现软开关的关键。然后研究了变换器的功率电路和控制电路，对钳位电容、检流电阻和高频变压器等主要参数做了详细推导和计算，根据电路拓扑特点给出了辅助开关管的负压驱动及同步整流管的电压自驱动方案，围绕峰值电流型控制器UCC2891，利用PC817和TL431的组合搭建了控制和电压反馈电路。最后根据各项参数的设计结果，在Pspice软件下搭建仿真电路，分析电路设计的可行性并做相应的优化和调整。在理论设计和仿真分析的基础上，制作了一台输入电压为45Vdc~72Vdc，开关频率为100kHz的有源钳位正激式软开关变换器，输出为12V/3A。经实验验证，主、辅功率开关管和同步整流管全都实现了零电压开通和关断，满载效率为85.6%，各项性能指标达到设计要求。
[Abstract]:As the volume of modern electronic products continues to decrease and the demand for efficiency becomes higher and higher, the switching power supply is also developing towards high power density, high efficiency, light weight, small volume and green. Soft switching technology and synchronous rectifier technology provide important technical support for the development of switching power supply in this direction, and also play an important role in the field of power supply. In this paper, the active clamp forward topology with synchronous rectifier is selected, and the soft switching effect of zero voltage turn-on and turn-off is achieved by using active clamp technology. The duty cycle of the converter can be greater than 50. The magnetic reset can be realized effectively by using the clamp circuit, and the main and auxiliary switches can be turned on and off at zero voltage, and the voltage and current spike and switching loss caused by the switch can be reduced. Using synchronous rectifier instead of common rectifier diode and using soft switch technology can further reduce the conduction loss and improve efficiency. Firstly, the advantages and disadvantages of several magnetic reset techniques of forward converter are discussed, the principle of synchronous rectification technology is analyzed, the two topologies of low edge clamp and high edge clamp are compared and analyzed, and the selection basis is given. The operation principle of topology in 12 stages in a switching cycle is analyzed, and the key to realize soft switching is given. Then, the power circuit and control circuit of the converter are studied, and the clamping capacitance is analyzed. The main parameters such as current detection resistance and high frequency transformer are deduced and calculated in detail. According to the circuit topology characteristics, the negative voltage drive of auxiliary switch tube and the voltage self-drive scheme of synchronous rectifier tube are given. Around the peak current mode controller UCC2891, the control and voltage feedback circuits are constructed by the combination of PC817 and TL431. Finally, according to the design results of various parameters, the simulation circuit is built under the Pspice software. Analyze the feasibility of circuit design and make corresponding optimization and adjustment. On the basis of theoretical design and simulation analysis, an active clamped forward soft-switching converter with an input voltage of 45VDC / 72Vdc and a switching frequency of 100kHz has been fabricated with an output of 12V / 3A. The auxiliary power switch and synchronous rectifier are all turned on and off at zero voltage, the full load efficiency is 85.6, and the performance indexes meet the design requirements.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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