开关变换器的模型分析是开关变换器研究的基础．对此，文中引入混杂系统理论，建立了基于切换系统的开关变换器统一模型，该模型不仅适用于DC-AC 变换器，而且适用于多种DC-DC 变换器．基于该模型的参数矩阵，提出系统Lyapunov 函数的构造方法，通过构造Lyapunov 函数得出系统切换律，分析该切换律条件下系统在切换平衡点的稳定性，并总结出建立该统一模型的一般方法和具体步骤．最后，对DC-AC 变换器、三电平Buck 型DC-DC 变换器进行仿真研究，验证了所建模型的合理性和建模方法的有效性．

As model analysis is the basis of the switching converter research,a switching system-based unified model is proposed according to the hybrid system theory,which is suitable for DC-AC and various types of DC-DC switching converters. Then,the construction method of Lyapunov function is proposed based on the parameter matrix of the unified model and the system switching laws are put forward by constructing this function. Meanwhile,the system stability under the proposed switching laws is analyzed and a general approach and some specific steps for the unified modeling are summarized. Finally,some simulations are carried out by establishing models for the DC-AC and three-level Buck-type DC-DC converters,and the rationality of the established models and the effectiveness of the modeling method and steps are both verified.