The Design Of High Frequency Isolated Grid-Connected PV Inverter

The current rapid development of society causes the great energy consumption. Energy and environmental problem have become increasingly prominent. Developing the utilization of clean renewable energy has been imperative. Solar energy is accepted for its advantages such as economical and cleanness commonly. Countries around the world encourage the development of Photovoltaic(PV). Inverter is the most important part in the PV grid-connected system. Grid-frequency isolated inverter exists lots of disadvantages such as noisy, bulky and heavy. This paper focuses on 3.5KW single-phase high frequency isolated grid-connected system. The topology, parameter selection, filter designing, control strategy, maximum power point tracking and anti-islanding are analyzed and studied in detail. The main contents are as follows:1) Introduce and compare the DC/DC topology which commonly used in the high-frequency isolated grid-connected system. Expound the reason why choosing the isolated Cuk topology as the DC/DC part of the high-frequency isolated grid-connected system. Briefly introduce the various components of the entire high-frequency isolated grid-connected system.2) The isolated Cuk topology is analyzed theoretically. The parameter calculation of the isolated Cuk topology has been derived. The parameters of high-frequency transformer are calculated. The control strategy and the design of control circuit have been introduced.3) The IGBT module that used in the single-phase bridge inverter has been selected. The output filter, power decoupling capacitance and control circuit has been designed. And the current tracking control strategy which make sure the output current and grid-voltage achieve the same frequency and phase has been introduced.4) The software including MPPT and anti-islanding has been designed.This system has lots of advantages such as light weight, small volume, low cost and isolation between solar cell array and grid. So the study of high-frequency isolated grid-connected system has a theoretical and practical value.