Design And Implement Of Solar Inverter Based On Intelligent MPPT Control

Nowadays,people pay more attention to the environmental pollution caused by the consumption of earth resources.The continuous consumption of traditional energy sources is no longer in line with the development trend of society.The development of clean renewable energy is imminent.With the vigorous development of the photovoltaic industry,the research and utilization of solar energy has already taken the lead in new energy,and the use of photovoltaic(PV)power generation has alleviated many negative effects caused by the use of traditional fossil energy,and it has become more and more popular.As the core component of photovoltaic power generation system,continuous optimization and upgrading of its performance has been a research hot spot for scholars at domestic and abroad.Unlike traditional inverter,solar inverter needs to convert the direct current generated by photovoltaic arrays or modules into electric alternating currents required for human daily production or grid-tied.The output power of photovoltaic power generation is closely related to the load.As the external conditions change,the power output of solar system has a maximum value,and the maximum power point tracking(MPPT)technology is required to enable the solar system or the PV module to provide the maximum power output,which requires solar inverter(MPPT)technology.The core technologies for determining the power generation and output power quality in solar inverter are maximum power point tracking technology and grid-tied technology.The maximum power point tracking technology is to effectively track the maximum output power of PV arrays or modules to obtain its maximum power and make use of solar energy extremely.The grid-tied technology is to feed the tracked maximum power energy to the grid successfully.To do this,it is necessary to research the corresponding grid-tied control strategy of the inverter.Solar micro-inverter was connected to the grid by a single module.It enhances the resistance of photovoltaic power generation system to shadow occlusion.At present,research on solar micro-inverter is increasing.In this paper,the control methods and techniques related to solar micro-inverter MPPT have been analyzed.The fuzzy logic control strategy was adopted to control MPPT.Based on the fuzzy theory,the fuzzy logic controller was designed.The output power variation and power variation rate of the PV module were chosen the two-dimensional input of the controller,and the output control amount is the duty cycle signal.Firstly,the simulation model is established in the MATLAB/Simulink software.The simulation results show that the designed fuzzy controller had an ideal control effect.Secondly,the grid-tied control strategy of the inverter has been studied.The double-closed loop grid-tied control strategy has been designed to control the grid-tied current.The current inner loop controls the grid-tied current and the grid voltage to reach the same frequency and phase,feed forward compensation designed to eliminate the influence of grid voltage on grid-tied current;voltage outer loop is also designed to ensure stable operation of the DC bus voltage.Finally,the full-system simulation model of solar micro-inverter has been established in the MATLAB/Simulink software.The simulation results show that the designed control strategy was successful and effective,meets the design requirements and achieves the design goals.Based on the analysis of control theory and the establishment of simulation model and simulation results,a solar micro-inverter with rated power of 190 W has been designed and developed.The device selection and hardware circuit have been analyzed and designed,including active clamp fly back circuit,full-bridge unfolding circuit,EMI filter circuit,auxiliary power circuit,drive circuit,control circuit and feedback networks circuit.All the hardware circuits have been designed based on the Altium Designer 10 software.The high-performance 16-bit dsPIC33FJ16GSX04micro-controller was selected as the main control chip of the inverter,and the control program was compiled in the MPLAB-X-IDE software program integrated development software.Upload the program file into the chip was writen by used the PICkit 3.5 program.In this paper,the solar grid-tied experimental platform has been constructed by use the 190 W solar micro-inverter designed and a 190 W module,and experimental research have been done and analyzed.The test and comparison have been finished with the solar grid-tied system constructed by the traditional solar micro-inverter under the same test conditions of the system.The results show that the systemconstructed by the solar micro-inverter designed in this paper can obtain higher power generation compared with the traditional micro-inverter system and achieve grid-tied successfully.