本文關鍵詞： 正激變換器 有源鉗位 軟開關 同步整流　出處：《華南理工大學》2014年碩士論文　論文類型：學位論文

【摘要】：隨著現(xiàn)代電子產(chǎn)品的體積不斷減小，對效率的要求越來越高，開關電源也在向高功率密度、高效率、重量輕體積小和綠色化等方向發(fā)展，軟開關技術和同步整流技術為開關電源往這個方向上發(fā)展提供了重要的技術支持，也在電源領域扮演著重要的角色。 本文選取具有同步整流的有源鉗位正激式拓撲，利用有源鉗位技術使開關管達到零電壓開通和關斷的軟開關效果，變換器工作占空比可以大于50%，利用鉗位電路能有效實現(xiàn)磁復位，，并且使主、輔開關管達到零電壓開通和關斷，減小開關引起的電壓電流尖峰和開關損耗；采用同步整流管代替普通整流二極管，并利用軟開關技術能進一步減小導通損耗，提高效率。 首先討論了正激變換器幾種磁復位技術的優(yōu)缺點，分析了同步整流技術的原理，對低邊鉗位和高邊鉗位兩種拓撲進行對比分析，給出選擇依據(jù)，重點分析了拓撲結構在一個開關周期中分為12個階段下的運行原理，并給出實現(xiàn)軟開關的關鍵。然后研究了變換器的功率電路和控制電路，對鉗位電容、檢流電阻和高頻變壓器等主要參數(shù)做了詳細推導和計算，根據(jù)電路拓撲特點給出了輔助開關管的負壓驅(qū)動及同步整流管的電壓自驅(qū)動方案，圍繞峰值電流型控制器UCC2891，利用PC817和TL431的組合搭建了控制和電壓反饋電路。最后根據(jù)各項參數(shù)的設計結果，在Pspice軟件下搭建仿真電路，分析電路設計的可行性并做相應的優(yōu)化和調(diào)整。 在理論設計和仿真分析的基礎上，制作了一臺輸入電壓為45Vdc~72Vdc，開關頻率為100kHz的有源鉗位正激式軟開關變換器，輸出為12V/3A。經(jīng)實驗驗證，主、輔功率開關管和同步整流管全都實現(xiàn)了零電壓開通和關斷，滿載效率為85.6%，各項性能指標達到設計要求。
[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.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM46

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