Research On Active Clamped Flyback Photovoltaic Micro Inverter

With the extreme shortage of global energy and the rapid deterioration of the environment,human beings urgently need renewable energy to improve the current energy consumption structure and protect the living environment on which humans depend.Solar energy is one of the most suitable energy found by human beings so far,and has been widely favored.Therefore,photovoltaic inverters have been developed rapidly,especially micro-photovoltaic inverters,which have small size and high energy utilization,and become an important component of photovoltaic power generation in the future.The micro-inverter uses a high-frequency switching device,and the higher the frequency,the smaller the volume.But at the same time,the switching loss is increased and the efficiency is lowered.For this reason,this paper mainly studies an active clamped flyback micro inverter.Through the analysis of the simulation and experimental results,it can be seen that the soft switch can be realized and the working efficiency of the system is improved.First,the active clamp circuit is added on the basis of the flyback micro-inverter,and the working principle of the flyback circuit,the active clamp circuit,the full bridge circuit and the filter circuit are analyzed in detail.Through the analysis of the working process of the active clamp circuit,the conditions for realizing the zero-voltage switch(ZVS)and the zero-current switch(ZCS)of the anti-parallel diode are obtained.Secondly,the system is mathematically modeled.Through the analysis of the model,the MPPT controller is designed to realize the maximum power point tracking of the system.In the off-grid mode,the voltage-current dual-loop PI controller is selected,In the grid-connected mode,the voltage loop PI controller and the current PR controller is selected.The stability of the system was verified by analyzing the Bode diagram.Thirdly,according to the technical indicators and hardware structure of the project,the main topology of the system has been designed in detail,and all components are selected in accordance with the design scope to ensure the safe operation of the system.Fourthly,in addition to the main topology,the operation of the system requiresthe assistance of peripheral circuits.This paper designs the sampling circuit,the drive circuit,the auxiliary power supply circuit and the communication circuit.Fifthly,the hardware parameter of the design are simulated and verified,and a250 W experimental platform is built.By analyzing the simulation waveform and the experimental waveform,it can be concluded that the topology implements soft switching.