【摘要】：隨著二次電源如超級電容等在光伏發(fā)電、高功率微波系統(tǒng)、不間斷供電、電動汽車、通信電源以及航空電源等領(lǐng)域應(yīng)用越來越廣泛,雙向DC-DC變換器應(yīng)運而生,迅速的成為了人們關(guān)注的熱點。高效高功率密度是現(xiàn)代電力電子技術(shù)發(fā)展的趨勢,而軟開關(guān)技術(shù)是提高電源工作頻率和效率的關(guān)鍵,這樣能大大減小電源的體積和重量,進一步提高功率密度。諧振型變換器有天然實現(xiàn)軟開關(guān)的優(yōu)勢,近年來成為學者們研究的熱點。本文以LLC諧振型變換器為基礎(chǔ),提出一種對稱工作的雙向LLC諧振型DC-DC變換器,驗證能量雙向流動對稱性,并著重研究了在負載為容性負載時的變換器控制方法,優(yōu)化調(diào)頻控制區(qū)域,實現(xiàn)開關(guān)管的軟開關(guān)。本文首先闡述了雙向DC-DC變換器存在的意義,以光伏系統(tǒng)中二次電源為超級電容的應(yīng)用為例對其在實際中的應(yīng)用進行了較詳細的介紹,對其研究現(xiàn)狀和大致分類進行了總結(jié)。然后對軟開關(guān)技術(shù)進行闡明,引出諧振型變換器存在的優(yōu)點。對常規(guī)的三種諧振型變換器總結(jié)比較優(yōu)缺點,引出本文研究的LLC諧振型變換器(LLC Resonant Converter,簡稱LLC-RC),以單向LLC-RC為例詳細介紹了它的三種工作模態(tài),并給出典型工作波形。利用基波近似等效法(Fundamental Harmonic Approximation,簡稱FHA)對LLC-R C建立穩(wěn)態(tài)模型,給出電壓增益曲線、電流值曲線以及ZVS實現(xiàn)條件。在雙向L LC-R C中添加附加電感,利用FHA模型設(shè)計電路參數(shù),建立雙向LLC-RC仿真模型,驗證能量雙向流動的對稱性以及軟開關(guān)等特性,為后面將其應(yīng)用在容性負載充電電源上提供依據(jù)。對容性負載的LLC-RC控制方法進行詳細闡述,建立仿真模型,確定調(diào)頻的控制方式,對FHA模型誤差進行仿真分析,為選取調(diào)頻工作區(qū)域提供理論依據(jù)。通過仿真驗證誤差非線性分析的正確性。為解決充電開始上涌電流過大的問題,改進了控制方法,采用兩階段PWM加調(diào)頻的控制。設(shè)計建立容性負載的全橋LLC-RC仿真模型,實現(xiàn)了輸入電壓600V-300V變化范圍內(nèi),輸出電壓均能實現(xiàn)額定60V輸出,并且輸出電流基本保持穩(wěn)定,輸入側(cè)開關(guān)管基本全過程實現(xiàn)ZVS,在開關(guān)頻率低于諧振頻率的工作階段,整流側(cè)二極管無反向恢復電流的問題。最后,基于TI公司的TMS320F28027編寫控制程序,根據(jù)實際計算設(shè)計電路參數(shù),搭建驗證容性負載LLC-RC實驗平臺,在輸入電壓為200V-100V范圍內(nèi),輸出最大電壓均達到160V,增益調(diào)節(jié)范圍為0.8-1.6。通過實驗驗證了選取工作區(qū)域的合理性以及PWM加調(diào)頻控制方式的正確性,同時也驗證了軟開關(guān)實現(xiàn)的正確性。
[Abstract]:As the secondary power supply, such as supercapacitor, is widely used in photovoltaic power generation, high power microwave system, uninterrupted power supply, electric vehicle, communication power supply and aviation power supply, two-way DC-DC converters emerge as the times require. Quickly became the focus of people's attention. High efficiency and high power density is the development trend of modern power electronics technology, while soft switching technology is the key to improve the working frequency and efficiency of power supply, which can greatly reduce the volume and weight of the power supply and further improve the power density. Resonant converter has the advantage of natural soft-switching, and has become a hot research topic in recent years. In this paper, based on the LLC resonant converter, a symmetrical bidirectional LLC resonant DC-DC converter is proposed to verify the symmetry of two-way flow of energy, and the control method of the converter when the load is capacitive load is studied emphatically. The frequency modulation control area is optimized to realize the soft switch of the switch tube. In this paper, the significance of bi-directional DC-DC converter is described firstly. The application of secondary power supply as supercapacitor in photovoltaic system is introduced in detail, and its research status and general classification are summarized. Then the soft-switching technology is expounded, and the advantages of resonant converter are introduced. This paper summarizes and compares the advantages and disadvantages of the three conventional resonant converters, and introduces the LLC resonant converter (LLC Resonant Converter, (LLC-RC) studied in this paper. Taking one-way LLC-RC as an example, the three modes of its operation are introduced in detail. The typical working waveforms are given. The steady state model of LLC-R C is established by using fundamental equivalent method (Fundamental Harmonic Approximation, (FHA). The voltage gain curve, current value curve and ZVS realization condition are given. An additional inductor is added to the bi-directional LLC-RC, and the circuit parameters are designed by using the FHA model. The bi-directional LLC-RC simulation model is established to verify the symmetry of the two-way energy flow and the characteristics of the soft-switching. It can be used in capacitive load charging power supply. The LLC-RC control method of capacitive load is described in detail, the simulation model is established, the control mode of FM is determined, and the error of FHA model is simulated and analyzed, which provides the theoretical basis for selecting the working area of FM. The correctness of the error nonlinear analysis is verified by simulation. In order to solve the problem that the charging start surge current is too large, the control method is improved, and the two-stage PWM plus FM control is adopted. The full bridge LLC-RC simulation model of capacitive load is designed and established. Within the range of input voltage 600V-300V, the output voltage can be rated 60V and the output current is basically stable. The input side switch can realize ZVS, in the whole process. When the switching frequency is lower than the resonant frequency, the rectifier diode has no problem of reverse recovery current. Finally, based on the TMS320F28027 of TI Company, the control program is compiled. According to the actual circuit parameters, the capacitive load LLC-RC experimental platform is built. In the range of input voltage 200V-100V, the maximum output voltage reaches 160V. The gain adjustment range is 0. 8. 6. 6. 6. The rationality of selecting the working area and the correctness of the PWM plus FM control mode are verified by the experiments. At the same time, the correctness of the realization of the soft switch is also verified.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TM46

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