Single‐phase transformerless bi‐directional inverter with high efficiency and low leakage current

This study proposes a high efficient bi‐directional inverter for a photovoltaic (PV) system integrated with an energy storage system. The proposed bi‐directional inverter controls the bi‐directional power flow and satisfies the power requirement between the grid and the dc sources. The proposed bi‐directional inverter achieves high efficiency by employing a transformerless structure and by minimising the power losses. The inverter structure can suppress the leakage current, which is considered to be one of the most important design parameters in a transformerless PV system. The efficiency and leakage current of the proposed bi‐directional inverter are analysed. Furthermore, its bi‐directional operation principles and control method are described. Finally, a 3‐kW prototype is implemented to confirm the theoretical analysis and the validity of the proposed bi‐directional inverter.