The Research Of MPPT Control In Grid-connected PV System Based On Soft Switching Technique

As global energy issues and ecological environment become more and more serious, the application of new energy, especially solar energy, has developed very fast for its unique lustration, safety and inexhaustible. And grid-connected technique has been studied all over the world.In this paper, we analyze and compare the main technical problems of Photovoltaic (PV) system and finally focus on the DC/DC converter and the maximum power point tracking (MPPT) control of the two lever PV system. An improved Buck-Boost circuit has been introduced. The paper also designs a new fuzzy controller to implement MPPT. The main contents are as follows:1. Make detailed contrast of different kind of DC/DC converters, which apply soft switching techniques. Then introduce an improved Buck-Boost topology as a DC/DC converter. The advantages of the circuit are examined both in theory and by using the Matlab/Simulink.2. Use fuzzy logic control to track the maximum power point of solar cells. Make analysis of fuzzy control's feasibility and characteristics. Design a new fuzzy logic controller by using 5 GUI tools in Fuzzy Toolbox of Matlab, and also found fuzzy control reasoning rules, which adapt to practical PV system.3. Combine the MPPT control and DC/DC converter as a whole, establish MPPT models of P&O method and fuzzy control method respectively on the basis of the improved Buck-Boost circuit mentioned above. The effectiveness of the algorithm and control methods have been validated, and the emulational results establish the soundness of the feasibility of the design.