A Fast Diagnosis Method Based on Open-Circuit Fault of Switch Tube of Cascade H-bridge Photovoltaic Inverter

摘要

Cascaded H-bridge multilevel inverter is the best choice in large-scale photovoltaic power generation system and has a good application prospect.With the increase of the number of modules in cascade, the probability of open-circuit fault of switch tube will also increase. This paper proposes a open-circuit fault diagnosis method for cascaded H-bridge photovoltaic inverter. The output voltage of each H-bridge module is collected at the top or bottom of the carrier and used as the criterion for determining open-circuit faults. After the diagnosis is completed, measures are adopted to reduce the degree of fault. Accurate positioning of the fault switch tube is accomplished in one carrier cycle. Simulation results have verified the effectiveness of the proposed method.