A Novel Topology And Control Algorithm For Improving Power-Density Of Single-Phase PV Inverter With Power Decoupling Function

Single-phase photovoltaic inverters are the key equipment of Distributed Renewable Energy and Energy Storage Grid-Connect System.On the premise of realizing the basic functions of the inverter,improving the power density,security and reducing the cost of the inverter have important theoretical and practical significance for improving the performance of Distributed Generation System.This paper focuses on improving the power density of single-phase inverter.In this paper,the Boost-type inverter topology is improved and a new control algorithm is proposed.And then the circuit parameters are designed.The main work and innovations of this paper are as follows.1.Firstly,this paper summarizes the background and development status of Photovoltaic grid-connect inverters.In this paper,the methods of improving power density and the control strategies of active power decoupling are reviewed.This establishes the research idea of "Power Flow Method" to improve the power density of inverters.2.Then,this paper analyzes two kinds of power that affects the volume of single-phase inverter,AC Power and DC Power.And the Volt-Ampere Area method for quantitative analysis of "Power Flow" is proposed.Based on this,the relationship between the volume of filter inductor and radiator of single-phase inverter and "AC power" of the system is further deduced,which provides a design method of novel topology and improved control algorithm.3.Secondly,the "DC power" and "AC power" of the inverter are analyzed based on Volt-Ampere Area diagram.Based on this,this paper draws the conclusion that the twolevel inverter has smaller "AC power",smaller filter inductance and smaller radiator volume.Based on upper conclusions,this paper improves the topology and control algorithm of Boost single-phase inverter.Compared with the traditional inverter topology,the inductance volume of the novel topology is reduced by 28%.And the radiator volume of the novel topology is smaller than that of the traditional topology.So the power density of the inverter is improved.4.Thirdly,the "optimizing decoupling capacitor reference voltage" power decoupling control method for the novel topology is proposed.Compared with the original control algorithm,simulation results show that the improved control method can make the inverter have better suppression effect of doubling frequency.5.Finally,based on MATLAB and DSP in the loop controlling RT-LAB platforms,the model of the proposed novel single-phase inverter is built.The simulation results show that the improved single-phase inverter can realize the power decoupling function.At the same time,compared with the traditional single-phase inverter,the novel topology has the advantages of smaller filter inductance and smaller radiator volume.