Design And Implementation Of Single-phase Photovoltaic Grid-connected Inverter Based On DSP

With the economic development,the world’s energy is becoming more and more nervous,and the solar energy because of a result of unlimited reserves,universal existence,the use of cleanliness,economic efficiency and other advantages,becomes the alternative energy that the world have sought.And the photovoltaic inverter as a kind of equipment which can effectively convert solar energy into available energy is paid much attention to.What is more,the improvement of control strategy,the improvement of conversion efficiency and the improvement of grid connection technology have been to be studied.Therefore,it has important theoretical and engineering value for its research.This dissertation has researched from topological structure selection,maximum power point tracking control,sinusoidal pulse width modulation method,phase-locked loop control and closed-loop control.Then,this dissertation designs a 1kW single-phase photovoltaic grid-connected inverter prototype based on DSP.Firstly,this dissertation briefly introduces the research background,significance,current situation and development trend of the photovoltaic grid-connected inverter.What is more,the composition of photovoltaic power generation system and the classification of photovoltaic grid-connected inverter are introduced.On these bases,this dissertation determines the main contents of the photovoltaic grid-connected inverter.Secondly,the basic theory of the photovoltaic grid-connected inverter is introduced in detail,and the single-phase non-isolated topology composed of Boost circuit and the full-bridge inverter circuit is selected.In addition,this dissertation has carried on the simulation for the different maximum power point tracking control algorithm,the phase-locked loop Control strategy and the grid-connected control strategy of grid-connected inverter under the simulation environment of Matlab/Simulink.By comparison with the simulation results,a conductive incremental method is chosen as the core algorithm of MPPT control,a second-order integral PI adjustment method is improved as the PLL control strategy and a double closed-loop control strategy for the inner loop of the voltage and the outer loop of the current is taken as a grid-connected control strategy.Then,this dissertation designs a photovoltaic grid-connected inverter with TMS320F28035 as the core of control.On the one hand,this dissertation has carried on the detailed introduction ahout the design of the parameters of the grid-connected inverter,the calculation of the main circuit parameters,the selection of the device and the minimum system circuit of the DSP,the auxiliary power supply circuit,the driving circuit,the sampling conditioning circuit and the protection circuit.On the other hand,this dissertation also gives the program flow chart of the grid-connected inverter software system and the implementation method of the PID control algorithm.Finally,in the simulation environment of Matlab / Simulink,the simulation model of the whole system is established,and the simulation output waveform is given,which has verified the feasibility of the design method.On the basis of simulation,this dissertation builds a 1kW photovoltaic grid-connected inverter prototype.And has conducted a different input power under the prototype experiment.The experimental record of the output waveform and the test data under different input power verify that the DSP-based single-phase photovoltaic grid-connected inverter designed by this dissertation meets the design performance requirements.