Half-Bridge Voltage Swing Inverter with Active Power Decoupling for Single Phase PV Systems Supporting Wide Power Factor Range

Photovoltaic (PV) inverters form the backbone of PV generation. This paper proposes an all-film-capacitor, transformer-less single phase inverter for PV application. The topology is a combination of a front-end boost stage, a half-bridge (HB) inverter stage, and a buck-boost power decoupling stage. The grid ripple power is decoupled by a large swing of the HB capacitors along with a limited ripple on the dc-link thus reducing the capacitance requirement and converter volume. Being a HB derived inverter, the high frequency common mode leakage current through the PV parasitic capacitance is mitigated. Further, the dc-link average is optimally controlled to ensure a higher efficiency over wide operating load and power factor range. To validate its operation, a Silicon Carbide (SiC) based 1 kVA laboratory prototype is built and closed loop experimental results are provided at 100/75 kHz switching frequency over wide operating conditions.