本文選題：寬輸入電壓范圍　切入點：三電平LLC　出處：《電子科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：近年來,燃料電池以其能量轉(zhuǎn)換效率高、環(huán)境友好度高等方面的優(yōu)勢得到了快速發(fā)展,燃料電池分布式電源作為燃料電池的重要應用之一,對其能量轉(zhuǎn)換系統(tǒng)的研究越來越關注。由于燃料電池隨著負載電流的增加,輸出電壓下降率大,即輸出電壓范圍較寬,并且燃料電池很難快速響應負載的突變,因此,對能夠滿足燃料電池輸出電壓范圍并擁有較快的動態(tài)響應特性的直流變換器的研究與開發(fā)已成為一項重要的課題。針對燃料電池能量轉(zhuǎn)換系統(tǒng)應用場合,本文以提高對寬輸入電壓范圍適應性為目標,采用全橋三電平LLC諧振變換器拓撲,并研究了其工作原理和電路特性,具體從以下幾方面開展了工作:首先,結合特定應用需求,對比研究了燃料電池能量轉(zhuǎn)換系統(tǒng)中的多種直流變換器拓撲,選定了最為匹配的全橋三電平LLC諧振變換器拓撲。針對傳統(tǒng)控制策略下諧振槽輸入電壓總諧波失真大的問題,本文提出一種改進型對稱雙移相控制策略,能夠?qū)崿F(xiàn)變換器三電平模式和兩電平模式的切換,并且降低了諧振槽輸入電壓的總諧波失真�；谠摽刂撇呗�,研究了LLC諧振網(wǎng)絡的直流增益特性、軟開關特性,并通過分析兩種策略下諧振槽輸入電壓的總諧波失真隨斬控角的變化,推導出改進型控制策略下的諧振槽輸入電壓總諧波失真小的結論,并仿真驗證了理論分析的正確性。其次,根據(jù)燃料電池能量轉(zhuǎn)換系統(tǒng)的具體設計要求,對全橋三電平LLC諧振變換器進行了詳細的參數(shù)設計,重點開展了諧振網(wǎng)絡的參數(shù)設計、高頻變壓器的設計,諧振電感設計等研究,并對數(shù)字控制器進行了優(yōu)化設計。此外,在Saber仿真環(huán)境下,搭建了全橋三電平LLC諧振變換器的仿真模型,仿真驗證了變換器對寬輸入電壓范圍的適應性、軟開關情況、輸出電壓紋波情況以及負載突變時系統(tǒng)的響應特性,最終驗證了全橋三電平LLC諧振變換器及所設計控制策略的正確性。最后,根據(jù)設計指標的要求及仿真分析結果,搭建了全橋三電平LLC諧振變換器的300W實驗樣機,進行實驗驗證,實現(xiàn)了改進型對稱雙移相控制策略,并且寬輸入電壓范圍適應性、軟開關情況以及效率等指標達到了預期要求。
[Abstract]:In recent years, fuel cell has been developed rapidly because of its high energy conversion efficiency and high environmental friendliness. Distributed power supply for fuel cell is one of the important applications of fuel cell. More and more attention has been paid to the research of the energy conversion system. Because the output voltage of the fuel cell decreases greatly with the increase of the load current, that is, the output voltage range is wide, and the fuel cell is difficult to respond to the sudden change of the load quickly. The research and development of DC converters which can satisfy the output voltage range of fuel cells and have faster dynamic response characteristics have become an important subject. In order to improve the adaptability to wide input voltage range, the full-bridge three-level LLC resonant converter topology is adopted in this paper, and its working principle and circuit characteristics are studied. The work is carried out from the following aspects: firstly, combined with the specific application requirements, In this paper, a variety of DC / DC converter topologies in fuel cell energy conversion systems are compared, and the most matched full-bridge three-level LLC resonant converter topology is selected. The problem of large total harmonic distortion of resonant slot input voltage under traditional control strategy is discussed. In this paper, an improved symmetric double-phase shift control strategy is proposed, which can realize switching between three-level mode and two-level mode, and reduce the total harmonic distortion of resonant slot input voltage. The DC gain and soft switching characteristics of LLC resonant network are studied, and the variation of total harmonic distortion of resonant slot input voltage with chopping angle is analyzed. The conclusion that the total harmonic distortion of the resonant slot input voltage is small under the improved control strategy is deduced, and the correctness of the theoretical analysis is verified by simulation. Secondly, according to the specific design requirements of the fuel cell energy conversion system, The parameters of full-bridge three-level LLC resonant converter are designed in detail. The parameters of resonant network, the design of high-frequency transformer, the design of resonant inductor are studied, and the digital controller is optimized. In the Saber simulation environment, the simulation model of full-bridge three-level LLC resonant converter is built. The simulation results verify the adaptability of the converter to the wide input voltage range and the situation of soft switching. The output voltage ripple and the response characteristics of the system under the load abrupt change finally verify the correctness of the full-bridge three-level LLC resonant converter and the designed control strategy. Finally, according to the requirements of the design index and the results of simulation analysis, A 300W experimental prototype of a full-bridge three-level LLC resonant converter is built and verified by experiments. The improved symmetrical double-phase shift control strategy is realized. The parameters of wide input voltage range adaptability, soft switching and efficiency are achieved.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TM46;TM911.4
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本文編號：1589637