Design Of Photovoltaic Grid-connected Inverter Control System Based On FPGA

The technology of Grid-connected photovoltaic power generation is a technology that converts solar energy into electricity.This topic is to research,design and develop an efficient and high-performance FPGA-based grid-connected photovoltaic power inverter control system,which has important social meaning and high economic significance.In this work,the photovoltaic(PV)grid inverter system is treated as the research object,The key part,which including the control system of PV grid structure,the maximum power point tracking(MPPT)technology,inverter SVPWM control,has been researched.What's more,the algorithm of MATLAB simulation,and the FPGA hardware implementation of the control system is carried out on the thorough study by the comparative analysis,the main research contents and conclusions are as follows:First,the development of photovoltaic industry on the basis of the present situation is present,PV grid power generation technology are reviewed.PV grid power generation system of the type and topology structure are briefly introduced.The main technical difficulties of grid-connected photovoltaic inverter control system are pointed out.And then,the working principle of grid-connected photovoltaic power generation system is analyzed,and the design simulation of each component is carried out,including the characteristics of PV cells and design and simulation,DC-DC converter,phase-locked loop principle and design simulation,design and selection of bridge inverter circuit,etc.For the implementation of MPPT,firstly,the various direct MPPT control algorithms based on the sampled data and the artificial intelligence MPPT control algorithms are analyzed and comparatively analyed.Based on this,the advanced incremental conductance of MPPT algorithm is proposed,compared with the traditional incremental conductance MPPT algorithm,it increases the total differential and variable step length,which lead to can rapidly and accurately track the maximum power point,reduce the tracking range and time,avoid therepeated shocks near the maximum power point,reduce the system error,make the system running effect is good,and easy to implement on FPGA chip.For the control mode of grid-connected photovoltaic inverter,the double closed-loop control of voltage outer loop and current inner loop is simply introduced.PWM adopts space vector pulse width modulation.Finally,SVPWM is used to drive the switch tube to realize the inverter process.Through analysis and research,the feasibility of the design is verified.Finally,the FPGA implementation of PV grid-connected inverter system is studied,including the design of MPPT module and SVPWM,Verilog HDL programming,simulation and hardware verification.The experimental results show that the program design is correct,and the FPGA realizes the maximum power tracking and SVPWM modulation function.Compared with the DSP system,the FPGA control system has the high reliability,strong real-time performance,high energy conversion efficiency,good system stability,and can be programmable on the spot and upgrad online.