Research On The Fuzzy Control MPPT Algorithm Based On The Linear Model Of Photovoltaic Cells

With the deterioration of the earth’s environment,countries all over the world are vigorously advocating the use of clean energy.As one of the clean energy sources,solar energy has been developed and used by people because of its pollution-free,large quantity and strong universality.In photovoltaic Power generation system,Maximum Power Point Tracking（MPPT）technology is one of the most effective means to ensure the efficient use of energy.At present,many MPPT methods have been proposed by scholars at home and abroad,among which fuzzy control MPPT method is a commonly used intelligent algorithm.These algorithms have remarkable effects in realizing MPPT control of photovoltaic system.Although there are many literatures on fuzzy MPPT method for photovoltaic power generation,there are few literatures on the combination of photovoltaic cell linearization model and fuzzy control MPPT method.To better study the photovoltaic（PV）system MPPT,the paper combines the PV cell linearization model with fuzzy control MPPT,and proposes two control algorithms,single fuzzy control and switching fuzzy control.The main contents are as follows:（1）A traditional photovoltaic cell MATLAB simulation model was built to analyze its output characteristics when external conditions changed.Several algorithms are analyzed and the simulation model of common algorithms is built to determine the research object of this paper.Several models of photovoltaic cell linearization are analyzed,and one of them is selected by comprehensive consideration.The purpose and significance of photovoltaic cell linearization and how to realize the linearization are analyzed in detail.（2）Analyze the advantages and disadvantages of common DC/DC conversion circuit and its application occasions,and choose Boost conversion circuit as the research object of this dissertation.The principle and design application of fuzzy controller are studied.A simplified single fuzzy controller is adopted.On the one hand,it can improve the design level and design idea of fuzzy control,and on the other hand,it can facilitate the selection of chip and the implementation of program.At the same time,the simulation models of several single fuzzy control MPPT methods are built,and compared with the traditional disturbance observation method,the effectiveness of each method is verified from multiple angles.（3）On the basis of single fuzzy,according to the optimization law of MPPT,a threshold value is designed to better realize MPPT,and a simulation model of switching fuzzy control is built.Compared with the traditional disturbance observation method,its effectiveness is verified.At the same time,a two-dimensional dual-input single-output fuzzy controller is designed to realize MPPT.Finally,the output characteristic curves of several algorithms are compared and analyzed.Considering the time-varying load,a time-varying resistor is designed to verify the performance of the algorithm respectively.Simulation experiments are carried out for each algorithm,and the experimental results verify the correctness,effectiveness and feasibility of the two algorithms.Finally,the comparison experiment proves that the two algorithms can simultaneously take into account the rapidity,accuracy and stability performance of MPPT control.