LCL滤波并网逆变器逆变侧电流多次采样的单闭环控制策略

Single Closed-loop Control Strategy Based on Multi-sampled Inverter Side Currents for Grid-connected Inverters with LCL Filters

针对LCL滤波并网逆变器,研究了基于多次采样的电流单闭环控制方案。在不改变开关频率的条件下,一个开关周期内进行多次采样并更新调制信号,有效减小数字控制延时,提高了系统控制带宽和稳定裕度。定量分析了多次采样数字控制延时特性,并分析了多次采样条件下LCL滤波并网逆变器的控制性能。与常规有源阻尼多环结构相比,该方案采用电流单环控制即可实现系统稳定,无需增加传感器,从而简化了控制结构。最后通过实验验证了该方案的有效性。

In connection with the grid-connected inverter with an LCL filter, a multi-sampling-based single closed-loop current control strategy is researched. In a switching period, data is sampled many times and the modulation signal is updated at the same time. As a result, the delay caused by digital control is greatly reduced without changing switching frequency, achieving high control bandwidth and large stability margin. The control delay based on multi-sampling is quantitatively analyzed, and the control performance of the grid-connected inverter with an LCL filter by multi-sampling is analyzed. Compared with the regular active damping method with multiple loops, the scheme adopting single current loop is seen to realize system stability without increasing sensors. Finally, experimental results show that the control scheme is effective.