三相电压型PWM整流器建模、控制及稳定性分析

三相电压型PWM整流器的状态空间模型具有多输入多输出的非线性结构。根据瞬时有功功率守恒原理,建立了整流器有功电流与直流母线电压之间的小信号模型。整流器工作在整流状态时,存在一个右半平面的零点,系统呈现出非最小相位特性。为了更加精确地分析在离散控制下整流器的性能,建立了三相PWM整流器采用电压、电流双闭环控制结构时系统的离散域模型,提出了电压、电流控制器参数的工程设计方法,并且详细地分析了系统各参数对系统稳定性的影响。研究结果表明:系统的稳定性主要受到了电压外环比例系数、交流侧滤波电感、母线电容、负载因素影响。最后,实验结果证明了上述理论分析的正确性。

Modeling,Control and Stability Analysis of Three-phase Voltage Source PWM Rectifier

State-space model for three-phase voltage source PWM rectifier has a multi-input multi-output (MIMO) nonlinear structure. According to instantaneous active power balance relation, a small-signal mathematical model for the relation between active current and dc-side bus voltage is proposed. When the rectifier operates in rectification mode, it has a zero point in right half plane (RHP) and exhibits non?minimum phase feature. In order to analyze the basic performances of the rectifier accurately under discrete control, a discrete domain model of three-phase PWM rectifier using dual-loop control structure of an outer voltage feedback loop and an inner current loop is established, the controller parameters of voltage and current loop are designed, and stability affected by variation of converter parameters is analyzed. Results show that the proportional gain of outer voltage loop, ac filter inductor, bus capacitor, and load are the main factors relevant to instability. At last, experimental results certify accuracy of theoretical analysis.