The Research On LLC’s Photovoltaic Power Equalizer

In recent years, Many countries in the world are facing the problems of energy crisis and environmental pollution caused by coal, oil and other traditional energy sources With the development of society, the search for renewable and non-polluting energy has attracted more and more attention from many countries. After the photovoltaic effect is found, Photovoltaic power generation has been considered to be an ideal clean energy, and gradually became the main way to get green energy.According to PV board’s connection mode, The mainstream mode of photovoltaic power generation has centralized mode, series mode and AC mode. AC mode is suitable for distributed photovoltaic power generation, due to the use of the number of photovoltaic panels can be very small, it is widely used In the family, the roof of the building. The centralized model and series model is through a certain number of PV in the series and parallel. When PV boards are used in series and parallel, the output energy level and power generation efficiency can reach very high, the energy can be directly input to the power grid through the inverter network and complete grid connected. Generally it’s used in large-scale photovoltaic power station because of huge amount of PV board and large occupied area.When the PV mask is covered in the series PV array, the whole series PV panel array will appear the situation of output power reduction and multi-peak. In this paper, the working state of the series PV panel array is analyzed in this paper, find the reasons for the output power reduction when the shading condition is obtained. A photovoltaic equalizer is proposed to solve the problem of reducing the output power of the shading case. According to the characteristics of photovoltaic power generation system, the LLC resonant topology is chosen as the realization circuit of the PV equalizer. After introducing the working principle of the LLC resonant topology, the small signal modeling of the LLC resonant topology is carried out by using the extended function description method.In order to verify the correctness of the circuit parameters, this paper use PSIM software to build a system simulation diagram. A digital control based 162W PV equalizer is produced, and use TMS320F28335 chip of TI’s company to complete the power control of the photovoltaic equalizer, timing control and series of protection functions. Finally, the debugging of the PV equalizer is finished.