High-reliability single-phase current source inverter with switching-cell structure for grid-connected photovoltaic systems

This paper presents a high-reliability current source inverter with a switching-cell structure for grid-connected photovoltaic systems. When compared to the conventional current source inverter, the proposed converter has no open-circuit issue, which can minimize the overlap time interval. As a result, the output waveforms quality is considerably improved. In addition, by adding capacitors, the high-frequency loops inside the inverter can be easily reduced to inhibit switching spikes. Common-mode chokes and split capacitors are also employed at the input to solve the leakage current problem of the photovoltaic transformer-less inverter. The operating principle of the inverter is analyzed. A 500 W prototype of a single-phase switching-cell (SC) current source inverter (CSI) was designed and tested to verify the feasibility of the circuit.