Research And Design On The MPT And DC/DC Convert Link Of PV Power System

With the increase of energy demand,the problem of energy shortage is becoming more and more serious,photovoltaic power generation can effectively solve the energy demand.The main function of DC/DC converter in photovoltaic system is to adjust the maximum power tracking.But in the light load condition,the efficiency of DC/DC converter is very low,and the photovoltaic array for a long time is working in light load conditions,which leads to the energy output of photovoltaic cells are wasted on the loss of the converter.In recent years,some foreign scholars have proposed that the converter with parallel structure can reduce the circuit loss by adjusting the number of working modules,so as to improve the efficiency of the converter.On this basis,this paper carries on the analysis from the angle of DC/DC converter circuit loss,established the efficiency model of multiphase interleaved DC/DC converter,analyzes the efficiency curve of the efficiency of the model,and the model is designed based on efficiency optimization control strategy,so as to realize the DC/DC converter light load efficiency under the optimized conditions,the main the work of this paper is as follows:Firstly,the PV array model and MPPT control technology are analyzed and studied.The working principle of the photovoltaic cell is analyzed,the mathematical model of photovoltaic cell and the engineering simulation model in MATLAB / Simulink is established,and the influence of light radiation and battery temperature on its output characteristics was analyzed by simulation.Then several common MPPT control algorithms are analyzed,and an MPPT algorithm based on adaptive variable step size is designed on the basis of conductance increment method.Secondly,the DC/DC converter of the PV system is analyzed.The DC/DC converter topology is designed to meet the technical requirements.The working principle of the multiplexed parallel boost circuit is analyzed,and designed the DC/DC converter main circuit parameters.According to the technical specifications of the system design the driver,sampling,protection and communication circuit.The efficiency optimization model of multi-phase interleaved parallel DC/DC converter is established,and the efficiency optimization model is analyzed.Based on this,a phase-adjusting control strategy based on optimal efficiency curve is proposed.Finally,the MPPT control algorithm,the efficiency model of the boost circuit and the simulation model of phase-adjusted control strategy based on efficiency model are set up in the MATLAB / Simulink environment.The accuracy and reliability of MPPT algorithm and phase adjustment control strategy are verified by simulation.The experimental results show that the output characteristics of the PV array and the accuracy of the maximum power tracking are verified.The efficiency of the four-phase interleaved boost circuit based on the optimal efficiency curve control is compared and analyzed.