Research On Wide Input Voltage Dual SEPIC Inverter For Photovoltaic Power Generation System

Solar energy is widely applied as a renewable energy because of its cleanliness,safety and reliability.In the photovoltaic grid connected power generation system,compared with the two stage PV grid connected inverter,the single stage inverter only needs the first order energy conversion to complete the grid connected inverter function,and has the advantages of simple circuit,little device,high efficiency and high reliability.Therefore,it has important research significance to complete the single stage inverter with wide input voltage and self boosting function.This paper presents an output parallel dual SEPIC single stage inverter for photovoltaic grid connected power generation system based on SEPIC DC converter.The inverter can achieve boost and depressurization,and the input voltage is wide.It has good adaptability to voltage change of photovoltaic cell,high conversion efficiency.The system is simple,high reliability and low cost.It is suitable for photovoltaic grid connected power generation system.On the basis of analyzing the current situation of the development of photovoltaic grid connected power generation system and the current research status of the photovoltaic grid connected single stage inverter,this paper introduces the overall scheme of the photovoltaic power generation system.This paper proposes a kind of output parallel double SEPIC single stage inverter according to summarizing the characteristics of the existing single stage inverter and combining the characteristics of SEPIC circuit and then ananlyzes the working principle in depth and the design method of circuit parameters in detail.Then the double SEPIC inverter fed by dual power supply is changed to double SEPIC inverter with single power supply according to the angle of input power supply.The simulation model of double SEPIC inverter with single power supply is built by MATLAB/Simulink software,and the DC/AC inverter function is verified by simulation.On the basis of the DC/AC inverter,a photovoltaic cell model is built to combine the photovoltaic cell with the single input dual SEPIC inverter and introduce the maximum power tracking(Maximum Power Point Tracking,MPPT)link of the PV grid connected system.The simulation verifies the feasibility of the single input dual SEPIC inverter relying on the appropriate strategies of grid control.Two methods of grid connected current control are adopted: half cycle control and hysteresis current control.The simulation results show that the hysteresis current control is effective.Finally,a prototype of dual SEPIC inverter based on TMS320F28335 is built,and giving the selection and design method of main circuit components of inverter.A half cycle controlled dual SPEIC inverter prototype is used to verify the feasibility of parameter design,grid connected control strategy and system plan.