本文選題：脈沖序列 + 低頻振蕩　； 參考：《西南交通大學》2017年碩士論文

【摘要】：脈沖序列(pulse train,PT)控制是一種開關DC-DC變換器的離散控制技術,它根據(jù)輸出電壓與參考電壓的比較結(jié)果,采用高低功率脈沖的不同組合形式,實現(xiàn)對開關DC-DC變換器輸出電壓的控制。當開關DC-DC變換器工作于CCM時,如果輸出電容的等效串聯(lián)電阻(equivalent series resistance,ESR)較小,電容兩端電壓與電感電流存在相位差,使得變換器輸出電壓無法嚴格按照高低功率脈沖的組合動態(tài)調(diào)節(jié),出現(xiàn)低頻振蕩現(xiàn)象。該現(xiàn)象出現(xiàn)時,變換器輸出電壓波形呈波動狀,嚴重影響變換器的穩(wěn)態(tài)性能。目前,對于低頻振蕩的解決方法可分為三類,分別為增大輸出電容的等效串聯(lián)電阻、改進控制方法和改變電路結(jié)構。這三種方法本質(zhì)上都是通過減小電容電壓和電感電流的相位差。電容電流脈沖序列(capacitor current pulse train,CC-PT)控制技術可以有效的解決某些工作場合下的變換器輸出電壓低頻振蕩現(xiàn)象,但當占空比大于0.5時,變換器仍會出現(xiàn)低頻振蕩。本文在深入分析CC-PT控制CCM Buck變換器輸出電壓低頻振蕩產(chǎn)生機理的基礎上,改進其控制得到滯環(huán)電容電流脈沖序列(hysteretic capacitor current pulse train,HCC-PT)控制技術,有效抑制占空比大于0.5時CC-PT控制Buck變換器的低頻振蕩現(xiàn)象。闡述了 HCC-PT控制Buck變換器抑制低頻振蕩的原理,分析了其能量模型及工作特性。本文在分析PT控制DCM Buck變換器不會產(chǎn)生低頻振蕩的原理基礎上,改變了Buck變換器的電路結(jié)構,使其工作于PCCM模式,通過采電容電流將PT控制應用到PCCM Buck變換器。搭建了電容電流型PT控制PCCM Buck變換器的實驗平臺,實驗結(jié)果表明,該方法不僅抑制了低頻振蕩現(xiàn)象,同時具有良好的瞬態(tài)性能。針對離散移相(discrete phase shifted,DPS)控制全橋變換器仍然存在的低頻振蕩問題,本文建立PT控制Buck型開關變換器通用等效電路模型,并將電容電流型PT控制PCCM變換器推廣到PCCM全橋變換器。該方法表明電容電流型PCCM開關變換器可以有效抑制低頻振蕩現(xiàn)象,并具有較好的可移植性。
[Abstract]:Pulse training PTC control is a discrete control technique for switching DC-DC converter. According to the comparison between output voltage and reference voltage, the output voltage of switching DC-DC converter is controlled by different combination of high and low power pulses.When the switching DC-DC converter works in CCM, if the equivalent series resistance of the output capacitance is small, the phase difference between the voltage and the inductance current at both ends of the capacitor is found.The output voltage of the converter cannot be adjusted strictly according to the combination of high and low power pulses and the low frequency oscillation occurs.When this phenomenon occurs, the output voltage waveform of the converter fluctuates, which seriously affects the steady-state performance of the converter.At present, the solutions to low frequency oscillation can be divided into three categories: increasing the equivalent series resistance of output capacitance, improving the control method and changing the circuit structure.These three methods are essentially by reducing the phase difference between capacitance voltage and inductance current.Capacitor current pulse training CC-PTT control technique can effectively solve the low frequency oscillation of output voltage in some workplaces, but when the duty cycle is greater than 0.5, the low frequency oscillation will still occur.Based on the analysis of the mechanism of low frequency oscillation of output voltage of CCM Buck converter controlled by CC-PT, the hysteretic capacitor current pulse training (HCC-PTT) control technique of hysteretic capacitor current pulse pulse sequence of hysteretic capacitor current pulse is improved.The low frequency oscillation of Buck converter controlled by CC-PT is effectively suppressed when the duty cycle is greater than 0.5.The principle of Buck converter controlled by HCC-PT to suppress low frequency oscillation is described, and its energy model and operating characteristics are analyzed.On the basis of analyzing the principle that PT control DCM Buck converter will not produce low frequency oscillation, the circuit structure of Buck converter is changed to make it work in PCCM mode. PT control is applied to PCCM Buck converter by collecting capacitive current.An experimental platform for capacitive current-mode PT controlled PCCM Buck converter is built. The experimental results show that the proposed method not only suppresses the low frequency oscillation, but also has good transient performance.In order to solve the problem of low frequency oscillation in discrete phase-shifted phase converter, a universal equivalent circuit model of PT controlled Buck switching converter is established, and the capacitive current-mode PT control PCCM converter is extended to PCCM full-bridge converter.The method shows that capacitive current-mode PCCM converters can effectively suppress low frequency oscillation and have good portability.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM46

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