本文選題：寬范圍輸入 + LLC諧振變換器　； 參考：《陜西科技大學(xué)》2017年碩士論文

【摘要】：隨著能源危機、環(huán)境污染問題的日益嚴(yán)重,充分利用可再生能源得到了人們的廣泛關(guān)注。而可再生能源發(fā)電單元普遍存在輸出電壓范圍較寬的特點,因此寬范圍輸入變換器被大量應(yīng)用在可再生能源發(fā)電單元的后級。目前所采用的級聯(lián)、串并聯(lián)以及多模式類等結(jié)構(gòu)的電路拓?fù)涠驾^為復(fù)雜,且無法兼顧變換器的高效率和寬范圍輸入。論文針對此問題,以變換器對寬范圍輸入的適應(yīng)性、高效性和高穩(wěn)定性為目標(biāo),運用LLC電路的效率優(yōu)勢,采用將VFM(Variable Frequency Multiplier)技術(shù)與Burst控制模式相結(jié)合的方法,研制了一種能夠滿足寬范圍輸入,且任何負(fù)載下都可實現(xiàn)高效化的LLC諧振變換器。論文主要工作總結(jié)如下:(1)變換器的工作原理分析及實現(xiàn)寬范圍輸入的研究。針對LLC諧振變換器不能夠滿足寬范圍輸入,分析和研究了其拓?fù)浣Y(jié)構(gòu),采用VFM技術(shù),縮小了諧振回路的輸入電壓范圍,使變換器能夠?qū)崿F(xiàn)寬范圍輸入,且在帶有20%以上負(fù)載時效率較高;詳細(xì)分析了變換器的工作原理,闡述了其增益特性、輸入阻抗特性、ZVS條件及輸入電容的電壓平衡特性等。(2)變換器的主電路設(shè)計。通過分析電路的設(shè)計指標(biāo)及結(jié)構(gòu),首先詳細(xì)設(shè)計了變換器的主電路參數(shù);其次對變換器所用到的元器件進行了設(shè)計與選擇,主要包括功率開關(guān)管的選取,諧振電容、諧振電感以及勵磁電感的設(shè)計與選擇,變壓器的設(shè)計,輸出整流二極管、輸出濾波電容等的選擇。(3)變換器的控制系統(tǒng)設(shè)計。采用擴展描述函數(shù)法建立了變換器的小信號模型,推導(dǎo)了其傳遞函數(shù),并根據(jù)不同的工作模態(tài)設(shè)計了對應(yīng)的控制器,使系統(tǒng)能夠滿足動態(tài)響應(yīng)要求。針對變換器輕載效率低的問題,采用了Burst控制模式,并進行了詳細(xì)設(shè)計,使變換器工作在輕載時也能夠達到較高的效率。(4)基于DSP的控制系統(tǒng)軟硬件設(shè)計。采用數(shù)字控制方式,對控制系統(tǒng)的硬件電路進行了設(shè)計,主要包括:驅(qū)動電路、輸出電壓采樣電路、輸出電流保護電路、數(shù)字采樣器等的設(shè)計。同時對變換器的主程序和子程序進行了設(shè)計,并根據(jù)離散化方法,完成了數(shù)字PI控制器的詳細(xì)設(shè)計,實現(xiàn)了對變換器的數(shù)字控制。(5)電路仿真及驗證。運用PSIM仿真軟件對設(shè)計的電路做了仿真分析,仿真結(jié)果表明理論設(shè)計合理;研制了一臺24V/1.5kW的實驗樣機,測試數(shù)據(jù)表明,該變換器可實現(xiàn)100V~400V的寬范圍輸入,當(dāng)20%以上負(fù)載時效率可達到94.8%~96.5%,當(dāng)5%~20%負(fù)載時效率能達到93.5%以上,當(dāng)小于5%負(fù)載時效率能達到87.8%以上,驗證了理論分析的可行性。論文研制的LLC諧振變換器可滿足寬范圍輸入的要求,并且在任何負(fù)載下都可實現(xiàn)ZVS,效率較高,具有輸出電壓穩(wěn)定、動態(tài)性能良好、控制精度高等優(yōu)點,在新能源發(fā)電方面有較好的應(yīng)用前景。
[Abstract]:With the energy crisis, the problem of environmental pollution is becoming more and more serious, and people pay more and more attention to the full use of renewable energy. Because of the wide output voltage range of renewable energy generation units, wide range input converters are widely used in the latter stage of renewable energy generation units. The circuit topology of cascaded, series-parallel and multi-mode classes is complex and can not take into account the high efficiency and wide range input of the converter. Aiming at this problem, aiming at the adaptability, high efficiency and high stability of the converter to wide range input, the paper uses the efficiency advantage of LLC circuit and combines VFM (variable Frequency multiplier) technology with burst control mode. A high efficiency LLC resonant converter is developed, which can satisfy the wide range input and achieve high efficiency under any load. The main work of this paper is summarized as follows: (1) Research on the principle of converter and wide range input. Aiming at the LLC resonant converter can not satisfy the wide range input, the topology structure is analyzed and studied. The VFM technique is used to reduce the input voltage range of the resonant circuit, so that the converter can realize the wide range input. The working principle of the converter is analyzed in detail, and the gain characteristic, the input impedance characteristic and the voltage balance characteristic of the input capacitance are expounded. (2) the main circuit design of the converter. By analyzing the design index and structure of the circuit, the main circuit parameters of the converter are designed in detail, and then the components used in the converter are designed and selected, including the selection of the power switch, the resonant capacitance, Design and selection of resonant inductor and excitation inductor, transformer design, output rectifier diode, output filter capacitance, etc. (3) Control system design of converter. The small signal model of the converter is established by using the extended description function method, and its transfer function is deduced. The corresponding controller is designed according to different working modes, so that the system can meet the requirement of dynamic response. In order to solve the problem of low light load efficiency, the burst control mode is adopted and the detailed design is carried out to make the converter work at low load to achieve higher efficiency. (4) the hardware and software design of the control system based on DSP. The hardware circuit of the control system is designed by using the digital control mode, including the design of the drive circuit, the output voltage sampling circuit, the output current protection circuit, the digital sampler and so on. At the same time, the main program and subroutine of the converter are designed. According to the discretization method, the detailed design of the digital Pi controller is completed, and the digital control of the converter is realized. (5) the circuit simulation and verification. The designed circuit is simulated and analyzed by PSIM software, and the simulation results show that the theoretical design is reasonable, and an experimental prototype of 24V / 1.5kW is developed. The test data show that the converter can achieve a wide range input of 100V / 400V. When the load is above 20%, the efficiency can reach 94.8%, when the load is 20%, the efficiency can reach 93.5%, and when the load is less than 5%, the efficiency can reach more than 87.8%, which proves the feasibility of theoretical analysis. The LLC resonant converter developed in this paper can meet the requirements of wide range input, and ZVSs can be realized under any load. The LLC resonant converter has the advantages of high efficiency, stable output voltage, good dynamic performance and high control precision. It has a good application prospect in the field of new energy generation.
【學(xué)位授予單位】：陜西科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM46

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