Research On Key Technologies Of Grid Connected Micro Inverter System

The demand for energy of human society is increasing, but the fossil energy of the earth will be exhausted over the next decades. In the same time, the use of fossil fuels make great pollution to the earth’s environment. The smog of domestic cities in recent years has illustrated. In addition to make the strategic plan of import and export of traditional energy, all the countries in the world strengthen the domestic research of new energy. China pays great attention to new energy research. As the key research and development, solar power has got strongly support in recent years. Photovoltaic industry has demonstrated the broad application prospect.This paper studied the core technology of photovoltaic power, and focused on the research of grid connected micro inverter system. Analyzed the overall architecture of gird-connected micro inverter system. Researched the topological structure of the core circuit. Based on the simulation model of PV module, put forward to the variable step incremental conductance method to improve tracking speed and precision. The experimental results showed that, the tracking speed from zero to 90% of maximum power point(MPP) of the variable step incremental conductance method is increased by 1 times than the fixed step perturbation and observation. Error with the maximum power point of the variable step incremental conductance method is zero, while on the same condition, the error of the fixed step perturbation and observation method if about 1W(step is 0.1V). Designed the LC-LC filter circuit to get better filtering effect based on the research of double frequency SPWM modulation. The simulation results showed that the total harmonic distortion rate of output voltage is 0.96% while the load changes. Designed the communication module of micro inverter system to make the system realize remote access and control. Designed a 200 W rated power inverter. The test results showed that, when input 24 V voltage, the inverter output 220 V 50Hz sinusoidal alternating current, and the system efficiency is 84.89%. Reached the design requirements.