1. Power density: The micro inverter requires a high power density, and the overall circuit should have a small volume.
2, conversion efficiency: Because the current photovoltaic cell energy conversion efficiency is not high, so every 1% increase in the efficiency of photovoltaic grid-connected equipment can bring great economic value.
3, reliability: the average first failure time (MTFF) of centralized grid-connected inverters is usually 5 years, and the average failure time (MTBF) is about 10 years. The life of photovoltaic cells is more than 20 years, so the life design index of micro-inverters must be equivalent to that of photovoltaic cells in order to reflect the advantages of the program. Its MTBF should be greater than 20 years, and the MTFF should be more than 10 years.
4, cost: The AC module system is configured with a micro inverter for each photovoltaic panel, which requires that the cost of the micro inverter is low, and the circuit should contain fewer devices. Its controller can handle all control, communication and computing tasks, and must have a low price.
At present, the research of traditional photovoltaic grid-connected system has achieved a lot of results, which can be used for reference in the design of micro-inverter grid-connected system. In this paper, the main circuits of different micro-inverters will be studied and analyzed
