开关DC-DC变换器电容电流脉冲序列控制

发布时间：2018-04-21 17:05

本文选题：电容电流 + 脉冲序列　；参考：《西南交通大学》2015年硕士论文

【摘要】：开关DC-DC变换器脉冲序歹(pulse train, PT)控制是根据输出电压与参考电压的比较结果,通过在两组驱动脉冲间切换的方式实现对输出电压的调整。PT控制不需要误差放大器及其补偿网络,因此具有控制实现简单、鲁棒性强、瞬态响应速度快等优点。目前对于PT控制的研究主要集中于开关DC-DC变换器工作于电感电流断续导电模式(discontinuous conduction mode, DCM),当开关DC-DC变换器工作在电感电流连续导电模式(continuous conduction mode, CCM)时,若输出电容等效串联电阻(equivalent series resistance, ESR)较小,PT控制开关变换器产生低频波动现象,并导致电感电流与输出电压的纹波较大,降低了变换器的工作性能。虽然增大输出电容ESR可以减小输出电压与电感电流的相位差,从而抑制变换器的低频波动现象,但同时也增大了输出电压纹波。为拓宽PT控制的应用范围,本文提出一种电容电流脉冲序列(capacitor current pulse train, CC-PT)控制方法。CC-PT控制通过采样电容电流并与预设的高、低电流基准比较,得到两组频率相同,占空比变化的高、低功率控制脉冲,实现对开关变换器输出电压的控制。本文以Buck变换器为例,深入研究和分析了CC-PT控制开关DC-DC变换器的工作特性。对于CC-PT控制DCM Buck变换器,通过理论计算给出了其输出功率范围、脉冲组合形式,并分析了变换器的输出电压纹波特性。对于CC-PT控制CCM Buck变换器,与PT控制进行了对比分析,阐述了其消除低频波动的机理,建立了相应的离散迭代映射模型。进一步,分析了CC-PT控制CCM Buck变换器的输出电压纹波特性以及瞬态响应特性。搭建了PT控制Buck变换器以及CC-PT控制Buck变换器的实验平台,实验结果很好地验证了理论分析的正确性。研究结果表明：CC-PT控制不仅保留了PT控制的快速瞬态响应特性,而且消除了PT控制开关DC-DC变换器工作在CCM时存在的低频波动现象,因而具有更优越的稳态性能和瞬态性能。
[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.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM46

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