状态空间法的非线性负载三相逆变器建模研究

Modeling of nonlinear load three-phase inverter based on state space method

含非线性负载的三相逆变器难以建立精确的数学模型,为此,文中以三相电压型SPWM逆变器为研究对象,提出一种基于状态空间平均法的非线性负载下三相逆变器建模的方法。根据三相逆变器的工作原理建立系统的小信号模型,利用相关坐标变换及状态空间平均法导出其状态方程,对其平均变量进行分离扰动和线性化处理,经过拉普拉斯变换后得到系统的状态空间平均模型。在Matlab/Simulink环境中分别搭建系统在线性负载和非线性负载条件下的方框图模型,对于两相旋转坐标系和三相静止坐标系下的三相逆变系统进行相应的仿真。结果表明,利用状态空间平均法对三相逆变器进行建模的可行性强,且所提方法具有仿真结果精确、误差小、鲁棒性强、仿真时间短等优点。

In allusion to the difficulty of establishing accurate mathematical model for three-phase inverter with nonlinear load,a method of three-phase inverter modeling under nonlinear load based on state space average method is proposed by taking three-phase voltage source SPWM inverter as the research object. The small signal model of the system is established according to the working principle of the three-phase inverter,and its state equation is derived by means of the correlation coordinate transformation and state space average method. The average variables are separated from disturbance and conducted the linear processing. The state space average model of the system is obtained after Laplace transformation. The block diagram models of the system under linear load and nonlinear load are built in MATLAB/Simulink environment. The simulation of three-phase inverter system in two-phase rotating coordinate system and three-phase static coordinate system is carried out accordingly. The results show that the state space averaging method is feasible for modeling three-phase inverter,and the proposed method has the advantages of accurate simulation results,small error,strong robustness and short simulation time.