三相SPWM逆变器的切换模型与稳定性分析

Modeling and stability analysis of three-phase SPWM inverter based on switched system theory

针对三相SPWM逆变器的近似线性化建模方法对系统分析的局限性,在周期切换理论的基础上对三相SPWM逆变器进行建模,并提出一种新型的稳定性分析方法。首先,在SPWM调制原理基础上,将一个工频周期按三相母线电压大小划分为6个区间,分别得到切换子系统与切换规则,即三相SPWM逆变器的周期切换模型。之后利用周期切换系统与多胞模型的稳定等价性,通过判断对应多胞模型的稳定性,实现三相SPWM逆变器的稳定性分析。仿真实验结果验证了切换模型以及稳定性分析方法的有效性,提高了系统模型的精确度和稳定性分析的灵活性。

Since the traditional modeling methods of three-phase SPWM inverter have introduced some limitations on the systems analysis, an improved modeling and stability analysis method was proposed based on periodic linear switched system theory. Firstly, one power frequency cycle was divided into 6 fractions from Sinusoidal Pulse Width Modulation to establish the switched subsystems and switching rules, which constitute the switched model of three-phase SPWM converter. Then a necessary and suffi-cient condition of asymptotical stability was derived for periodic switched linear systems, and the condi-tion was used to analyze the stability of three-phase SPWM inverter by robust stability criteria for polytop-ic-type uncertainties system. The simulation results verify the effectiveness of the switched system model and the proposed stability analysis. The accuracy of SPWM inverter model and the flexibility of corre-sponding stability analysis strategy are improved by the novel method.