【摘要】：隨著信息技術的快速發(fā)展,低壓大電流變換器在計算機、通信等領域中得到廣泛的應用。現在的低壓大電流變換器大都采用隔離型BUCK變換器,為了降低變換器輸入直流母線損耗和減小輸入濾波器的體積,變換器的輸入電壓在不斷的提高,而變換器的輸出電壓更低,輸出電流更大,開關頻率不斷提高,因此傳統(tǒng)的BUCK變換器已不能滿足低壓大電流變換器的要求。本文在分析國內外低壓大電流變換器發(fā)展的基礎上,通過對幾種典型主電路拓撲的對比選擇,確立了全橋倍流同步整流電路為主電路拓撲,并對其工作原理以及工作模態(tài)作了理論分析。在低壓大電流輸出場合,采用同步整流技術可以彌補傳統(tǒng)二極管整流損耗大的缺點,實現了高效率的DC-DC變換。采用倍流整流技術,由于兩個輸出濾波電感交錯并聯(lián),可以有效的抑制輸出電流紋波,減小電感的尺寸。目前,對全橋變換器的研究大都采用移相控制技術,本文采用移相控制技術,并利用變壓器的漏感同開關器件的結電容實現全橋開關管的軟開關,減小了開關管的開關損耗,進一步提高了變換器的效率。本文采用電壓閉環(huán)控制,提高整個變換器的穩(wěn)定性。UC2875是一款移相諧振控制器,它的控制方式完全符合全橋倍流同步整流軟開關變換器的需求。HIP4081是一款高頻全橋FET驅動器,能夠輸出四路相互隔離的驅動脈沖。本文使用UC2875和HIP4081共同實現主電路的移相控制,給出了主開關器件實現ZVS的具體條件和參數設計,同時對設計了變換器的主電路、控制方法、變壓器,并使用PSPICE仿真軟件對變換器系統(tǒng)進行了仿真驗證,仿真結果與理論分析一致。最后,本文以上述理論為基礎,成功設計了一臺輸入36~60V,開關頻率100KHz,輸出3.3V,0~15A的變換器實驗樣機,其各項實驗結果均滿足設計指標要求,實驗驗證了所做理論分析的正確性。
[Abstract]:With the rapid development of information technology, low voltage and high current converters have been widely used in computer, communication and other fields. At present, most of the low-voltage and high-current converters use isolated BUCK converters. In order to reduce the input DC bus loss and reduce the volume of the input filter, the input voltage of the converter is constantly improving, while the output voltage of the converter is lower, the output current is larger, and the switching frequency is constantly increasing. Therefore, the traditional BUCK converter can no longer meet the requirements of low-voltage and high-current converters. In this paper, based on the analysis of the development of low voltage and high current converters at home and abroad, through the comparison and selection of several typical main circuit topologies, the main circuit topology of full bridge current doubling synchronous rectifier circuit is established, and its working principle and working mode are analyzed theoretically. In the case of low voltage and high current output, synchronous rectification technology can make up for the shortcomings of traditional diode rectifier loss, and realize high efficiency DC-DC transformation. The current doubling rectifier technology can effectively suppress the output current ripples and reduce the size of the inductance because of the staggered parallel connection of the two output filter inductors. At present, the phase shift control technology is mostly used in the research of full bridge converter. In this paper, the phase shift control technology is adopted, and the soft switching of the full bridge switch is realized by using the leakage inductance of the transformer and the junction capacitance of the switching device, which reduces the switching loss of the switch tube and further improves the efficiency of the converter. In this paper, voltage closed-loop control is used to improve the stability of the converter. UC2875 is a phase-shifting resonant controller, which fully meets the requirements of full-bridge current doubling synchronous rectifier soft-switching converter. HIP4081 is a high frequency full-bridge FET driver, which can output four isolated driving pulse from each other. In this paper, UC2875 and HIP4081 are used to realize the phase shift control of the main circuit, and the specific conditions and parameter design of the main switching device to realize ZVS are given. at the same time, the main circuit, control method and transformer of the converter are designed, and the converter system is simulated and verified by PSPICE simulation software. The simulation results are consistent with the theoretical analysis. Finally, based on the above theory, an experimental prototype of converter with input 36 鈮，

本文編號：2500865