The Design Of500W Single-phase PV Grid-connected Inverter

Solar energy resources are inexhaustible green energy, and photovoltaic powergeneration catches the world’s attention as an effective way of using solar energyresources. PV grid-connected technology has higher energy efficiency and lowermaintenance costs. PV inverter is the key of grid-connected PV system and thedesignation of its hardware system and the research of control strategy has becomehot topics in the photovoltaic grid-connected field. Based on in-depth study andunderstanding of the latest research results of the field of photovoltaic powergeneration, this paper designs a500W single-phase photovoltaic grid-connectedinverter, and carries out in-depth analysis on the designation of hardware system,control strategy and computer simulation. This paper mainly discusses followingtopics:(1) The hardware system of single-phase photovoltaic grid-connected inverterwith two-stage DC-DC-LFAC topology is designed.The Modules including the maincircuit of inverter, auxiliary power circuit, detection circuit, driver circuit and so onare introduced. The working principle of each module and the selection process of themain components is introduced detailedly. The allocation method of the DSPhardware resource is introduced briefly.(2) The operating principle, equivalent circuit model and engineeringmathematics model of solar cells is introduced. A MATLAB simulation model of solarcells is built up. The principle and process of maximum power point tracking isdescribed, and various maximum power point tracking algorithm is studied in virtueof simulation model. Maximum power point tracking by using genetic algorithmcombined with perturbation and observation control is put up, and simulation isconducted through Genetic Algorithm Toolbox, the algorithm is proved to haveexcellent anti-interference ability and a faster search speed by the result of thesimulation.(3) Control strategy of single-phase photovoltaic grid-connected inverter isdiscussed and a comparative analysis of the hysteresis current tracking control andSPWM current control is conducted.The principle of the SPWM closed-loop current control is introduced detailedly,and it is validated by simulation. The implementationprocess on the TMS320F2812is introduced at last.(4) The software system based on TMS320F2812is completed, the software isdivided into many modules, such as software phase-locked loop based on DSP, FIRFilter, IIR filter, signal prediction and so on. The software system is completedthrough DSP/BIOS which is published by TI as a real-time multi-tasking operatingsystem.