Single Phase Isolated Bidirectional Inverter with Battery Interface for Solar Energy Applications

Photovoltaic systems need to be coupled with bidirectional inverters to effectively interface with energy storage in batteries and energy from the grid when available. The challenge, therefore, is to select the appropriate topology and control strategy that will yield a satisfactory response time while maintaining an harmonic distortion that complies with standards. The present work proposes a topology for an isolated bidirectional inverter capable of drawing energy from the grid to recharge the photovoltaic system's battery bank and vice versa. Three control strategies, PI control, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$d q$</tex> based control, and fuzzy logic-based control, are tested under the MATLAB/Simulink environment. The main benefit of the proposed topology and its control over existing topologies is that it offers lower battery current ripple and improved transient dynamics. A comparison with experimental results demonstrates the relevance of the proposed topology and the type of control that is most suitable for the specific need.