功率变换器非线性不稳定行为的washout滤波器控制方法

In many applications, e.g., light load mode, the Power Factor Correction (PFC) converter may exhibit bifurcation at the line frequency, which results in an unacceptable power factor. The DC-DC converter frequently exhibits slow-scale instability, which jeopardize performance of the system. There exist some complex methods of controlling the above instability. A simple and effective method of using the washout filter was proposed by us, which adds only one order to the converter. But the effect of the washout filter on the converter was not addressed, and the method can be further improved. The present study extends the washout filter-aided method and gives some interesting results: (1) Based on the double averaged model of the PFC converter and the slow-scale model of the DC-DC converter, the effect of the washout filter on the performance of the converter is analyzed; (2) An analytical expression of the output of the filter is given, and its effect on the equilibrium point is studied; (3) The critical boundary of the control variables in the washout filter is calculated; (4) A new method of using partial information of the output of the washout filter to control slow-scale bifurcation of the DC-DC converter is proposed, which makes the design of control circuit more simple;(5) A new fast method for studying nonlinear dynamics of the PFC converter is proposed based on a combination of continuous model and discrete model. The new methods resulting from this study will be attractive for both engineering and theory analysis, and give thorough guidance to engineers adopting the washout-filter-aided method.

功率因数校正(PFC)变换器线频率分岔引起功率因数大幅下降；直流变换器慢时标不稳定现象降低变换器性能。和已有的复杂方法相比，我们提出的采用washout滤波器控制上述不稳定现象的方法只使系统增加一阶，因而结构最简单。但此方法中滤波器对系统响应的影响尚缺深入理论分析且方法仍可改进。本课题进一步研究：(1)通过建立PFC变换器的双平均模型和直流变换器的慢时标模型，研究washout滤波器对变换器性能尤其是响应速度的影响；(2)得到滤波器输出的表达式以研究它对平衡点的影响；(3)针对PFC变换器采用解析或数值拟合的方法确定滤波器控制参数边界值表达式；(4)研究如何利用滤波器输出的部分信息来控制直流变换器，从而简化控制电路；(5)把连续和离散模型相结合建立更快速的PFC变换器非线性动力学行为分析方法。本课题将为washout滤波器方法的工程实践提供理论指导并扩展变换器非线性动力学行为的控制研究。

功率因数校正(PFC)变换器线频率分岔引起功率因数大幅下降；直流变换器慢时标不稳定现象降低变换器性能。和已有的复杂方法相比，我们提出的采用 washout 滤波器控制上述不稳定现象的方法只使系统增加一阶，因而结构最简单。但此方法中滤波器对系统响应的影响尚缺深入理论分析且方法仍可改进。本课题在研究washout滤波器控制PFC变换器和直流变换器非线性动力学行为的基础上，结合国际上提出的新技术又研究了延时控制器在两种变换器中的应用规律，主要研究了：(1)通过建立 PFC 变换器的双平均模型和直流变换器的慢时标模型，研究washout 滤波器和延时控制器对变换器性能的影响；(2)研究washout滤波器和延时控制器对变换器原平衡点的影响；(3)针对 PFC 变换器采用解析或数值拟合的方法确定了滤波器控制参数边界值表达式，确定了延时控制器控制参数边界值表达式，针对直流变换器采用特征多项式或者准特征多项式确定了滤波器和延时控制器控制参数边界值表达式；(4)研究了新型变换器非线性现象控制方法。本课题为 washout 滤波器方法的工程实践提供了理论指导并扩展变换器非线性动力学行为的研究。