Research On Micro Photovoltaic Inverter And Improved MPPT Control Method

The micro photovoltaic power generation system has been widely applied with the development of solar technology.Compared with the traditional high-power integrated photovoltaic power generation system,each photovoltaic panel in the micro photovoltaic power generation system corresponds to a low-power inverter module.The output power of the inverter restricts the rapid development of the photovoltaic power generation system.In addition,the output power of the photovoltaic cell is nonlinear with the ambient temperature and illumination intensity.Therefore,the maximum power point tracking(MPPT)technology has practical significance for improving the conversion efficiency.In this paper,the micro photovoltaic inverter is taken as the research object,and the theoretical analysis,simulation and experimental research on the composition of photovoltaic power generation system are developed.Additionally,the software and hardware design of micro photovoltaic inverter and the realization of MPPT are also carried out.Firstly,the structure of photovoltaic power generation system and the working principle of photovoltaic cells are introduced.The equivalent circuit of photovoltaic cells is studied.A simulation model is established based on MATLAB/Simulink.The simulation input of the model is temperature and illumination intensity,and the output of photovoltaic cells will change with the input.Secondly,it introduces the working principle of MPPT and analyzes the advantages and disadvantages of the well-known MPPT methods.Based on the traditional fixed step perturbation observation method,an improved step progressively variable step-size MPPT algorithm is proposed.The MPPT simulation model of photovoltaic power generation system is established based on boost circuit.The effectiveness and superiority of the proposed algorithm are proved by comparing the simulation results of the new algorithm and the traditional algorithm.Thirdly,the hardware circuit and software program of the micro-photovoltaic inverter are designed in detail,including the main circuit,detection circuit,drive circuit,filter circuit,etc.The software program includes the main program,interrupt program,protection program and so on.Finally,the micro photovoltaic inverter experiment platform is built,and the solar tracking experiment is completed based on this platform.The steady-state performance,dynamic performance and output efficiency are verified between the traditional and improved variable step-size method.The experimental results show that the proposed algorithm has good tracking performance and its output efficiency is obviously improved.