Research And Design Of Two-channel Staggered Flyback Grid-connected Micro Inverter

Aiming at the 600 W to 800 W power level photovoltaic modules in the market,this paper improves the existing topology and designs a two-channel grid-connected inverter after comprehensively considering the power cost.After selecting the flyback topology,according to the primary and secondary transformer,the whole system is divided into primary side and secondary side.By comparing the characteristics of the three operating modes of the flyback inverter,the compound peak current control strategy is proposed to ensure that the dual-channel staggered flyback grid-connected inverter can give full play to the best working ability under light or heavy load.The resonant soft switching technology is analyzed to improve the switching efficiency while reducing the switching loss.According to the large capacity decoupling capacitor that must be used in the hardware structure,the relationship between the output current of photovoltaic module and the decoupling capacitor and the primary current of flyback inverter is analyzed and obtained,and the MPPT algorithm which does not need to detect the output current of photovoltaic module is proposed.According to the system division of primary side and secondary side,the software and hardware parts of the system are designed.Based on the hardware system parameters design control circuit,auxiliary power circuit,PLC circuit,EMC filter circuit,analysis and calculation and select the components of the relevant circuit.In terms of software algorithm,three anti-islandings strategies are analyzed and compared,and the active anti-islandings strategy is selected and simulated.Considering that this paper is a dual control chip with abundant on-chip resources and limited hardware phase-locking accuracy,a software phase-locking,namely D-Q rotating coordinate phase-locking,is proposed.In order to realize power frequency inverter before current connection,a full bridge control algorithm is proposed.Power line carrier communication is selected and described according to the existing system resources.Finally,a prototype of the two-channel staggered flyback grid-connected micro inverter with power of 720 W is developed,which verifies the reliability of the hardware and software design of the system and the stability of the system.