A Novel Approach for Implementing and Optimizing Proportional-Resonant Controller and L-C-L Filter for Single-Phase Grid-tie Inverter

This article introduces the design procedure of a 1-phase full-bridge inverter for grid-connected applications. The main idea of modelling a full-bridge inverter is that it plays a vital role in solar energy systems. The dynamic equations are formed with the state-space averaging (SSA) technique. A Small-signal averaged model of a full-bridge inverter is constructed by assuming grid current and capacitor voltage as the two states. The voltage and current controller scheme are based on the frequency domain approach. The voltage controller is designed to maintain fixed voltage, and the current controller is used for controlling grid current. The LCL filter is connected to the inverter to provide better harmonic elimination and filter size minimization. This filter is formed by parallel-series combination of inductance and capacitance to improve the overall system performance. Here, a passive damping method is incorporated to make a balanced steady system. Finally, a proportional integral and proportional resonant (PI-PR) controller is introduced to provide better stability and tracking. The detailed analysis of PR controller is explored and demonstrated by MATLAB simulation.