基于误差信号反馈的单相LCL型逆变器谐振抑制方法

Resonance damping method of single-phase inverter with LCL-filter based on error signal feedback

LCL滤波器可对逆变器输出电流所包含的高频谐波产生显著的衰减效果,但其本身的三阶谐振特性容易影响系统的稳定性。针对该问题,在传统单相LCL型并网逆变器并网电流反馈控制方法和电网电压比例前馈控制策略的基础上,提出了一种基于误差信号反馈的新型控制策略,首先根据L滤波器和LCL滤波器在低中频范围内频率特性基本一致的特点,估计出LCL滤波器谐振峰被抑制后的输出电流,而后将实际电流与估计值之差反馈到控制回路中以抑制谐振。从理论上分析了该方法对系统稳定性的影响,并给出相应参数的设计方法,最后通过仿真和实验结果验证了所提控制策略的正确性和有效性。

LCL filter has a significant attenuation effect on high frequency harmonics contained in the output current of the inverter,but its own third-order resonance characteristics easily affect the stability of the system.To solve this problem,an error signal feedback control method was proposed on the basis of the traditional current feedback control method and grid voltage feed-forward control strategy for LCL-type inverter.Firstly,the output current when the resonant peak of LCL filter has been suppressed was estimated based on the fact that LCL filter has the same frequency characteristics with L filter in low frequency range,and then the difference between the actual current and the estimated value was fed back to suppress resonance.The influence of the method on the stability of the system was analyzed,and the parameter design method was provided.Finally,the simulation and experimental results verify effectiveness of the proposed control strategy.