基于虚拟电阻阻尼的三相并网逆变器控制设计

Design of Three-phase Inverter Controller Based on Virtual Resistors

为抑制三相并网逆变器中LCL滤波器带来的谐振尖峰,提出一种结合有源阻尼和无源阻尼方案的虚拟电阻阻尼设计,用来取代常见的串联在电容上的电阻。通过对系统传递函数和波特图的分析比较,给出一种基于检测电容电流的虚拟电阻阻尼设计方案;运用Matlab仿真验证了设计方案的有效性,同时也证实了其相对传统无源阻尼法对电流THD的改善;最后,仿真证实了虚拟阻尼法在发生跳载时能快速响应,并一定程度上抑制超调量。

To suppress the resonant peak of the LCL filter in a three-phase inverter, this article proposes a conception of virtual resistors which combines the traditional methods of active damping and passive damping so that the resistors which are in series with capacitors can be replaced. By analyzing the transfer function and bode plot of the system, a method of designing virtual resistors by measuring currents on capacitors is illustrated. The reliability of this design is testified by Matlab simulation, which also shows the improvement of THD of phase currents. Finally, the simulation verifies the fast response to switch in loads and the ability to check overshoot.