Small-capacity grid-connected solar power generation system

A small-capacity grid-connected solar power generation system, configured by a dual-output DC-DC power converter and a seven-level inverter, is proposed in this study. Voltage doubler based topology is used to configure the dual-output DC-DC power converter to convert the output voltage of a solar cell array into two dependent voltage sources with multiple relationships. The grid-connected seven-level inverter is configured by a dual-buck power converter and a full-bridge power converter. The dual-buck power converter is switched at high-frequency pulse-width modulation to generate a four-level DC voltage. The full-bridge power converter is switched synchronous with the utility voltage, to convert the four-level DC voltage into a seven-level AC voltage. The proposed solar power generation system generates a sinusoidal output current in phase with the utility voltage. The novelty of this proposed seven-level inverter is that two asymmetric DC voltage sources are used to increase the voltage levels and only two of the six power electronic switches in the seven-level inverter are switched at high frequency. A prototype is developed and tested to verify the performance of the proposed solar power generation system. The experimental results show that the proposed solar power generation system has the expected performance.