基于LCL滤波器的PWM整流器稳定控制研究

Study of Stability Control Strategy of PWM Rectifier Based on LCL Filter

LCL滤波器能有效抑制整流器对电网的谐波污染,同时LCL滤波器的使用也带来了系统稳定性的问题。有效地利用数字控制中的零阶保持和一拍控制延时,通过改变电流传感器的位置,将并网电流作为反馈量,便可使PWM整流器稳定运行。通过将系统的传递函数从S域映射到Z域中,利用系统闭环离散传递函数的根轨迹证明了所提方法的可行性,最后通过仿真和实验进行验证,表明所提方法只需改变电流传感器位置,无需在滤波电容中串联电阻,无需引入额外的反馈量,也无需在原有的控制算法中做任何改变,即可做到与无源阻尼法同样的控制效果。

LCL filter has also brought problems of system stability, while LCL filter is well suppressed rectifier high frequency harmonic pollution effectively.Make the use of zero-order hold and one shot control delay in digital control effectively,feedback the grid current instead of the current of rectifier,the PWM rectifier can run stablely.Map the transfer function of the system from the S domain to Z domain, then use the root locus of the closed loop discrete transfer function to analysis the feasibility of the proposed method.Finally, prove that just change the position of the current sensor, doesn＇t need to series damping resistors in the filter capacitor, neither add an additional amount of feedback, nor change the control algorithm the rectifier can performance as well as the rectifier with passive damping.