Design Of Photovoltaic Power Equalizer Based On Two-transistor Forward Circuit

With the rapid development of society,the consumption rate of fossil energy for traditional power generation is too fast,and harmful gases have been produced.As a new clean energy,solar photovoltaic power generation is not only rich in resources and easy to access,but also no pollution to the environment.Therefore,more and more attention has been attached to the photovoltaic power generation.Every government has also strongly supported the development of technology of using this renewable energy.While photovoltaic panels are working,the heat spot effect can be caused by shielding,uneven illumination and other reasons which eventually lead to lower output power.This paper focuses on how to increase output power and equalize output voltage by adding equalizer.In this paper,PSIM simulation software is used to simulate photovoltaic series and to verify the validity and reliability of photovoltaic cell models.In this paper,the equalization mechanism of power equalizer is analyzed in detail at first,and the average model of forward equalizer is given.Then the average equivalent model circuit of the closed-loop system of the equalizer is built by PSIM.The photovoltaic module has nonlinear ?-? characteristic and the equalizer is a switching converter with strong nonlinearity,which leads to the increase of computational complexity and the difficulty of convergence.The average model is a large signal model which neglects the high frequency ripple of DC converter and reserves the steady-state and low-frequency characteristics,so it can be used in analysis for steady state,AC/DC mixing analysis and small signal disturbance.By comparing rates of simulation results of the average model and the transient model,it is shown that the average model can improve the simulation efficiency by 32 times.Moreover,the topology and working principle of isolated two-transistor forward circuit with single-input and multi-output are given.The parameter calculation of the main circuit is designed in detail.The control circuit is designed by transformer drive control using UC3842.In PSIM,the closed-loop simulation of the whole system is carried out.Finally,the forward equalizer prototype is made and debugged.The feasibility of the equalizer is verified by the simulation and experimental results.