Design And Optimation Of Flyback Photovoltaic Grid-Connected Micro-inverter

The interest in exploring clean and renewable energies has grown in recent years due to the global energy crisis and the strong desire of protect environment. Photovoltaic (PV) sources are treat as the most promising and available alternative energy sources because of multitudinous natural advantage. The chief method of use Photovoltaic (PV) sources is build Grid-connected power generating system. Distributed generation based on Micro-inverter is more reliable, higher MPPT efficiency, more convenient to expand, therefore research on micro-inverter is significant.This research mainly focus on the flyback grid-connected micro-inverter which is less magnetic device and simpler controlled. First of all, the advantage and disadvantage of discontinuous conduction mode(DCM) and continuous conduction mode(CCM) flyback micro-inverter are compared and analyzed, the micro-inverter work in CCM is researched implemented. And then detailed analysis the operational principle of CCM micro-inverter, design active clamp circuit, detailed explain the operation process of auxiliary active clamp and the condition of achieve ZVS of main switching mosfet.Secondly,250W power rating CCM micro-inverter is detailed design in this paper, power convert circuit designing, choosing power device, power dissipated calculating is included, PI controller is also design based on conventional CCM control method. However, the conventional CCM control method based on ideal condition is defective, which significantly affect the quality of the output current of the micro-inverter. Based on the actual situation presents a new control method based on segmented feedforward compensation, this method can significantly improve the micro-inverter output current quality full-power segment, and in the segment of small and medium power to improve the quality of the output current is particularly significant.Finally, simulation platform is built in the Matlab/Simulink, and on the basis of theoretical analysis, an250W experimental prototype of PV grid-connected micro-inverter based on STM32was constructed. The simulation and experimental results demonstrate the feasibility of the proposed method.