Analysis On MPPT Sampling Period Of The Boost-based Photovoltaic Power Generation System

In recent years,in order to alleviate the shortage of fossil fuel,photovoltaic industry becomes the focus of the academic research discussion.However,any kind of photovoltaic system need to be equipped with the photovoltaic system technology(MPPT)to achieve high efficiency power generation function.Some experiments show that the reasonable sampling period of the system output power can effectively improve the efficiency of maximum power tracking technology.In this paper,by analyzing the working principle of photovoltaic cells and Boost converter,it is concluded that the input and output of them have obvious nonlinear characteristics.The combination of them makes photovoltaic system nonlinear degree more complicated,so that it is difficult to accurately determine proper sampling period of each operating point in MPPT by mathematical means.Then,according to the principle of the step response of the Boost circuit,this paper analyzed the sampling period working mechanism of the system output power.And based on the simulation and sampling of the Boost-based photovoltaic power generation system's the optimal sampling period during MPPT,this paper has found the distribution pattern of the sampling period.The maximum of optimal sampling period approximates to a constant value under different environmental conditions,thus it selects the constant value as sampling period suitable for the whole process of MPPT,which ensured the tracking speed and tracking precision of MPPT.This paper,by using MATLAB/Simulink software has set up a simulation platform for the photovoltaic dc converter part.In the certain illumination and temperature,the simulation system using the Perturbation and Observation(P&O)for the different sampling period has carried on the simulation under,it contrastively verified the reasonable sampling period can ensure tracking speed and tracking accuracy of the MPPT algorithm,and the selected sampling period is rationality.In addition,hardware experiment platform is constructed and experimental results demonstrate the rationality of the selected sampling period.