Research And Design On Photovoltaic Grid-connected Inverters

Fossil energy crisis that Human is facing now need to address throughrenewable energy urgently. With the constant advances in technology, solar energyas inexhaustible renewable energy from aerospace and other high-end applicationsquickly spread to people’s daily lives. With the large-scale production ofphotovoltaic modules， the cost of PV fall quickly. Large-scale applications of PVbecomes possible. As the key device of PV, Grid-Connected inverter is the core ofenergy conversion and control. Its performance not only affect stability, security,reliability of the entire PV grid-connected system, but also decide the life andefficiency. Inverter plays a crucial role in the application and promotion ofphotovoltaic system.This thesis mainly analysises and researches the conversion efficiency, powerquality, operational reliability on the Single-phase Photovoltaic Grid-ConnectedInverter. The inverter is designed for engineering needs and characters ofphotovoltaic systems. The final achievement is the inverter prototype.Firstly, This thesis analysises the theory of inverter topology and controlstrategy, and determine the structure of inverter for its character. Finally completethe design of general planning project.Based on the above， I design the main circuit and control circuit bothhardware circuit for the main circuit of inverter. Power module IGBT, DCcapacitors and filter inductor are calculated and selected. Control circuit for signalcollection, signal conditioning, DSP signal, the drive signal were designed in detailalso.From an engineering needs, this thesis completes an overall design of thesoftware flow pattern, and provides a detailed flowchart of SPWM current tracking, MPPT, anti-islanding control.Finally, I make a3kW single-phase grid-connected inverter prototype and builda test platform to test and analysis key performance such as device temperature,waveforms of output voltage and current, harmonic distortion, power factor,conversion efficiency. The test result meets all aspects of the design requirementsfully.