Research On Dead-beat Proportional Resonance Control For Three-phase Four-leg Grid-connected Inverter

With the development of new energy generation technology,distributed generation system has developed rapidly.Grid-connected inverter is the core equipment connecting power grid and distributed power generation device,the quality of its output current directly affects the quality of power grid.In this thesis,the gridconnected inverter is taken as the research object and the goal is to improve the output current quality of the grid-connected inverter.The dead-beat proportional resonance strategy is studied in detail.The main contents are as follows:The power conversion circuit of grid-connected inverter is designed.Based on the analysis and comparison of several common inverting bridge topologies,three-phase four-legs structure is selected as the inverting bridge structure.LCL filter is selected as the filter structure according to the requirement of high frequency harmonic suppression.The components of the inverter-bridge and filter are analyzed and their parameters are calculated,and the type selection is carried out.The control circuit of grid-connected inverter is designed.On the basis of demand analysis,the overall scheme of the control circuit with DSP as the core is designed,and the functional circuits are designed in detail,including sampling circuit,driving circuit,temperature detection circuit and protection circuit,the model and parameter of the components are analyzed and calculated,the model of each component is determined,and the PCB board of each circuit is drawn.A dead-beat proportional resonance controller for grid-connected inverter is designed.In order to reduce the difficulty of analyzing the LCL filter model,the LCL filter model was reduced to the L filter model by taking advantage of the low frequency similarity between the LCL filter model and the L filter model,and dead-beat controller is designed based on this model.Aiming at the problem of large errors and harmonics in the current control of the dead-beat controller,the advantages of the dead-beat controller with fast response speed and the proportional resonance controller with strong harmonic elimination ability were comprehensively utilized to form the deadbeat proportional resonance controller with two kinds of controllers in parallel.The simulation results show the effectiveness of the proposed strategy.The experimental platform of grid-connected inverter is constructed and the experimental research is carried out.The software scheme is designed to realize the control strategy of dead-beat proportional resonance.The experimental platform with d SPACE and DSP as the core controllers is constructed.The static and dynamic experiments are carried out by using d SPACE and DSP as the controllers respectively.In the two modes,the dead-beat proportional resonance controller has good current error elimination ability and high order harmonic elimination ability.Experimental results verify the effectiveness of the proposed strategy.