Research On Micro PV Grid-connected Inverter And Its Synchronization Grid-connected Control

The global energy issue has always been a focus of attention,and the development and utilization of new energy is the current research hotspot.Photovoltaic power generation is safe,reliable,pollution-free and noise-free.It is an effective way to develop new energy sources.The micro photovoltaic grid-connected inverter is one of the core technologies of the photovoltaic power generation system.It has received great attention in recent years and has high research and application value.This paper makes a detailed analysis of the micro PV grid-connected inverter,and conducts in-depth research on its principle structure and control strategy.The main work of the dissertation is as follows:1.The principle and structure of micro PV grid-connected inverter are analyzed.The topology and working principle of the DC-DC pre-stage of the micro photovoltaic grid-connected inverter are analyzed and designed.The analysis and comparison of the top-level structure of the DC-AC is advanced and the improvement scheme is given.2.Designing the control strategy based on the design of the topology.The maximum power tracking in the DC-DC pre-stage has been analysis.Comparing the advantages and disadvantages of several commonly used maximum power tracking algorithms,then the variable step-size interference observation method was selected and verified by simulation;sliding mode control was selected as the closed-loop control strategy for DC-DC stage;a three-closed-loop control strategy based on voltage loop,current loop and phase-locked loop has been adopted as the closed-loop control strategy for DC-AC stage;finally,detailed analysis and simulation experiment verification of the synchronous grid-connected control in the micro-grid system where the micro photovoltaic grid-connected inverter is located.3.Development of hard/software design for micro photovoltaic grid-connected inverter.The hardware includes:the main circuit of the design parameters of the flyback high-frequency transformer,flyback active clamp main MOSFET power tube selection,DC-DC output rectifier diode selection,DC-AC filter inductance parameters in the design,Signal detection circuit,drive circuit and power supply design,schematic and PCB diagram are given;software includes;the main program flow chart,ADC sampling program flow chart,PWM wave and SPWM generation flow chart and fault detection flow chart.4.The Matlab/simulink software was used to carry the simulation model of the entire micro PV grid-connected inverter.At the same time,two 300W experimental prototypes were developed.Through the analysis of the simulation results and experimental results of the prototype test,the effectiveness of the designed topology and control strategy is verified.