Research On High Voltage Transmission Ratio Three-phase Boost Mode Grid-connected Inverter

With the growing world energy crisis, development of renewable clean energy hasbecome a widespread concern around the world.Grid-connected inverter can transform DCpower such as the batteries，solar cells and fuel cells converted by various renewable energyinto the grid.So it is the key technologies and have important position in the development andutilization of the renewable energy.In this paper， the detailed discussion to the actuality and development of thegrid-connected inverter techenology and deep study of grid-connected inverter are given，andhigh voltage transmission ratio three-phase Boost mode grid-connected inverter isproposed.The circuit can realize grid inverter through single-stage power conversion and havethe advantages such as simple structure，small size，light weight and long life etc.And it is moresuitable for solar cells with low-voltage output for its hige voltage transmission ratio.The circuit topology，SPWM control strategy，the working principle and operationalmodes，characteristics，MPPT，design criterion of key circuit parameters of the high voltagetransmission ratio three-pahse Boost mode grid-connected inverter are deeply investigated inthis paper. A novel and digital three-phase reference sinusoidal circuit synchronous with theline voltage is proposed and investigated. The experimental results have been shown that thethree-phase reference sinusoidal circuit has the advantages such as the output voltagesynchronous with the line voltage，low THD，adjustable peak voltage which is free from thefluctuation of the line voltage, simplicity, utility and low cost.The correction and feasibility of the high voltage transmission ratio three-pahse Boostmode grid-connected inverter are verified by the theoretical analysis and simulation results of3kVA40-60VDC/380V50HzAC，and the simulation results show that the grid-connectedinverter can achieve high-quality grid-connected current and the regulation of reactive power.The Boost grid-connected inverter together with Buck and Buck-Boost grid-connected inverterconstitute the complete，unified grid-connected inverter technology theory.