Proportional-Resonant Controller And LCL Filter Design For Single-Phase Grid-Connected PV Micro-Inverters

This paper presents a brief behavior description of LCL filters through the analysis of its frequency response and the convenience of its use instead L filters. Moreover, the equations that allow its design and implementation are also described. Regarding the Proportional Resonant (PR) controllers, their behavior, discretization techniques and digital implementation are also studies. The developed systems are evaluated by mathematical model simulation and experimental prototype test. It is concluded that, for inverters operating as a current source, the PR controllers are suitable to follow a sinusoidal reference signal. On the other hand, LCL-type filter largely eliminates the harmonic content of the output current, making it compatible for Grid-Connected PV micro-inverters.