開關DC-DC變換器電容電流脈沖序列控制
發(fā)布時間:2018-04-21 17:05
本文選題:電容電流 + 脈沖序列 ; 參考:《西南交通大學》2015年碩士論文
【摘要】:開關DC-DC變換器脈沖序歹(pulse train, PT)控制是根據輸出電壓與參考電壓的比較結果,通過在兩組驅動脈沖間切換的方式實現對輸出電壓的調整。PT控制不需要誤差放大器及其補償網絡,因此具有控制實現簡單、魯棒性強、瞬態(tài)響應速度快等優(yōu)點。目前對于PT控制的研究主要集中于開關DC-DC變換器工作于電感電流斷續(xù)導電模式(discontinuous conduction mode, DCM),當開關DC-DC變換器工作在電感電流連續(xù)導電模式(continuous conduction mode, CCM)時,若輸出電容等效串聯電阻(equivalent series resistance, ESR)較小,PT控制開關變換器產生低頻波動現象,并導致電感電流與輸出電壓的紋波較大,降低了變換器的工作性能。雖然增大輸出電容ESR可以減小輸出電壓與電感電流的相位差,從而抑制變換器的低頻波動現象,但同時也增大了輸出電壓紋波。為拓寬PT控制的應用范圍,本文提出一種電容電流脈沖序列(capacitor current pulse train, CC-PT)控制方法。CC-PT控制通過采樣電容電流并與預設的高、低電流基準比較,得到兩組頻率相同,占空比變化的高、低功率控制脈沖,實現對開關變換器輸出電壓的控制。本文以Buck變換器為例,深入研究和分析了CC-PT控制開關DC-DC變換器的工作特性。對于CC-PT控制DCM Buck變換器,通過理論計算給出了其輸出功率范圍、脈沖組合形式,并分析了變換器的輸出電壓紋波特性。對于CC-PT控制CCM Buck變換器,與PT控制進行了對比分析,闡述了其消除低頻波動的機理,建立了相應的離散迭代映射模型。進一步,分析了CC-PT控制CCM Buck變換器的輸出電壓紋波特性以及瞬態(tài)響應特性。搭建了PT控制Buck變換器以及CC-PT控制Buck變換器的實驗平臺,實驗結果很好地驗證了理論分析的正確性。研究結果表明:CC-PT控制不僅保留了PT控制的快速瞬態(tài)響應特性,而且消除了PT控制開關DC-DC變換器工作在CCM時存在的低頻波動現象,因而具有更優(yōu)越的穩(wěn)態(tài)性能和瞬態(tài)性能。
[Abstract]:Based on the comparison between output voltage and reference voltage, switching between two groups of driving pulses, the output voltage is adjusted. PT control does not require an error amplifier and its compensation network. Therefore, it has the advantages of simple control, strong robustness and fast transient response. At present, the research of PT control is mainly focused on the on-off DC-DC converter working in discontinuous conduction mode. When the on-off DC-DC converter works in the continuous conducting mode of inductance current, the switching DC-DC converter works in the continuous conducting mode of the inductance current. If the equivalent series resistance of output capacitance is smaller than that of equivalent series resistance (ESRs), the low frequency fluctuation is produced in the PT controlled switching converter, and the ripple between the inductance current and the output voltage is larger, which reduces the performance of the converter. Although increasing the output capacitance ESR can reduce the phase difference between the output voltage and the inductor current and thus suppress the low frequency fluctuation of the converter, it also increases the ripple of the output voltage. In order to widen the scope of application of PT control, this paper presents a capacitive current pulse sequence capacitor current pulse training (CC-PTT) control method. High duty cycle and low power control pulse can control the output voltage of switching converter. Taking Buck converter as an example, the working characteristics of DC-DC converter controlled by CC-PT are studied and analyzed in this paper. For DCM Buck converter controlled by CC-PT, the output power range, pulse combination form and output voltage ripple characteristic of the converter are given by theoretical calculation. The CC-PT control CCM Buck converter is compared with PT control. The mechanism of eliminating low frequency fluctuation is expounded, and the corresponding discrete iterative mapping model is established. Furthermore, the output voltage ripple characteristics and transient response characteristics of CCM Buck converter controlled by CC-PT are analyzed. The experimental platforms of PT control Buck converter and CC-PT control Buck converter are built, and the experimental results verify the correctness of the theoretical analysis. The research results show that the control not only preserves the fast transient response of PT control, but also eliminates the low frequency fluctuation of PT control switch DC-DC converter operating in CCM, so it has better steady-state performance and transient performance.
【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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