Research On Single Phase Photovoltaic Grid-Connected Inverter

Photovoltaic (PV) grid-connected generation is one of the main forms of utilizing solar energy. The grid-connected inverter is the core component in the whole PV grid-connected system, undertakes the dc to ac energy conversion function. In order to ensure stability and reliability of the PV grid-connected generation system, it is necessary to make deeply research on PV grid-connected inverter. Two-stage single-phase PV grid-connected inverter has advantages of small volume and high power conversion efficiency,which has been used widely in low power (within 5kW) single-phase PV grid-connected system in recent years. This thesis focuses on the research of two-stage single-phase PV grid-connected inverter.This thesis first analyzes the basic principles and main electric parameters of solar cells, then builds a Matlab simulation model of solar cell and analyzes solar cells output characteristic curve in detail by using the model. After summarizing the advantages and disadvantages of traditional maximum power point tracking (MPPT) algorithm combined with output characteristic curve, this thesis presented a MPPT algorithm based on Boost converter along with system simulation by Matlab to confirm the algorithm validity.Secondly, the thesis deals with the study of topology structure for two-stage single-phase PV grid-connected inverter. By detailed analyzing voltage and current changes on the key components for the main circuit, the theoretical formulas of key inverter components parameter are proposed.And then, a detailed analysis on the overall control strategy of two-stage single-phase PV grid-connected inverter focuses on deducing deadbeat control algorithm of single-phase full-bridge inverter circuits. And on this basis a Matlab/Simulink platform of the inverter is built up. The simulation results prove the excellent properties of the control strategy.Finally, according to the research results, a 2kW single-phase PV grid-connected inverter prototype has been developed, software and hardware design solutions of which are introduced in detail, and part of the experimental waveforms are given.