The Research And Realization Of Maximum Power Point Tracking Algorithm For Photovoltaic Generation System

With the fast development of economy,the problems of energy shortage and serious environmental pollution have gradually caused widespread concern.People begin to seek some green renewable energy.At this time the solar energy come into the public,s view as a large,widely distributed emerging energy.As the main use of solar energy,photovoltaic grid-connected power generation has been the problem of low conversion efficiency,the main factor is the output of photovoltaic cells will change alone with the external environment changes,can not always maintain the maximum power output,resulting in reduced light energy utilization.Therefore,the focus of this paper is to find a suitable method to maximize the use of solar energy.This article mainly completed the following aspects of the work.(1)This paper discusses the current situation,background and existing problems of PV industry at home and abroad,and then focuses on the development of the maximum power point tracking method,and compares the development history and advantages and disadvantages of various algorithms.(2)The working principle of the photovoltaic cell and the mathematical model are analyzed in this paper.The simulation model of the photovoltaic cells is built in MATLAB/Simulink and its output characteristics under different environmental conditions are analyzed.Then the structure of the photovoltaic power generation system is classified according to the application.(3)Aiming at the problems existing in the traditional maximum power point tracking method,an improved algorithm is proposed,and the algorithm is simulated and analyzed in MATLAB/Simulink.Firstly,the advantages and disadvantages of the traditional MPPT algorithms are discussed.Then,the duty cycle perturbation method based on the function model is put forward.The algorithm is divided into two parts,one is the determination of the duty cycle disturbance function,the other part is the determination of the disturbance period.The duty cycle disturbance function consists of a two-dimensional Gaussian function and an arctangent function,the perturbation period is a function of the duty cycle.Then the algorithm simulation model is set up in MATLAB/Simulink to verify the feasibility of the algorithm,and the algorithm's working characteristics are tested when the key parameters of the algorithm are changed.(4)In this part,the main circuit of this paper is determined,including two parts.Pre-stage DC/DC circuit using fly-back converter circuit,after the DC/AC circuit using full-bridge inverter circuit,and design related circuit parameters.Then,the fly-back circuit model is set up in the MATLAB/Simulink environment and the fly-back circuit is simulated and analyzed,and the output efficiency of the fly-back circuit under different algorithms is compared.The test results of the fly-back circuit are in accordance with the analysis requirements,which shows the feasibility of the circuit.Compared with the three algorithms,we can see that the improved algorithm proposed in this paper is more efficient than the other two algorithms when it is applied,which shows the superiority of the algorithm.(5)On the basis of previous experiments,a 250 W photovoltaic micro-inverter test prototype is built in the basis of TI company TMS320F28035 chip,and test the correct design of the contents of the previous.