脉冲序列控制开关DC-DC变换器低频振荡抑制方法研究

发布时间：2018-04-16 18:46

本文选题：脉冲序列 + 低频振荡　；参考：《西南交通大学》2017年硕士论文

【摘要】：脉冲序列(pulse train,PT)控制是一种开关DC-DC变换器的离散控制技术,它根据输出电压与参考电压的比较结果,采用高低功率脉冲的不同组合形式,实现对开关DC-DC变换器输出电压的控制。当开关DC-DC变换器工作于CCM时,如果输出电容的等效串联电阻(equivalent series resistance,ESR)较小,电容两端电压与电感电流存在相位差,使得变换器输出电压无法严格按照高低功率脉冲的组合动态调节,出现低频振荡现象。该现象出现时,变换器输出电压波形呈波动状,严重影响变换器的稳态性能。目前,对于低频振荡的解决方法可分为三类,分别为增大输出电容的等效串联电阻、改进控制方法和改变电路结构。这三种方法本质上都是通过减小电容电压和电感电流的相位差。电容电流脉冲序列(capacitor current pulse train,CC-PT)控制技术可以有效的解决某些工作场合下的变换器输出电压低频振荡现象,但当占空比大于0.5时,变换器仍会出现低频振荡。本文在深入分析CC-PT控制CCM Buck变换器输出电压低频振荡产生机理的基础上,改进其控制得到滞环电容电流脉冲序列(hysteretic capacitor current pulse train,HCC-PT)控制技术,有效抑制占空比大于0.5时CC-PT控制Buck变换器的低频振荡现象。阐述了 HCC-PT控制Buck变换器抑制低频振荡的原理,分析了其能量模型及工作特性。本文在分析PT控制DCM Buck变换器不会产生低频振荡的原理基础上,改变了Buck变换器的电路结构,使其工作于PCCM模式,通过采电容电流将PT控制应用到PCCM Buck变换器。搭建了电容电流型PT控制PCCM Buck变换器的实验平台,实验结果表明,该方法不仅抑制了低频振荡现象,同时具有良好的瞬态性能。针对离散移相(discrete phase shifted,DPS)控制全桥变换器仍然存在的低频振荡问题,本文建立PT控制Buck型开关变换器通用等效电路模型,并将电容电流型PT控制PCCM变换器推广到PCCM全桥变换器。该方法表明电容电流型PCCM开关变换器可以有效抑制低频振荡现象,并具有较好的可移植性。
[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.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM46

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