The Research Of Interleaved Flyback Photovoltaic Grid-Connected Micro-Inverter Based On Active Clamp

As a research hotspot in recent years, AC modular photovoltaic grid-connected power generation system solved the problems of hot spot effect, which the traditional centralized or string type photovoltaic power generation system could not solve. The main content of this paper is about the core component of AC modular photovoltaic grid-connected power generation system -- micro-inverter.Firstly, the existing micro-inverter topologies were classified and described, and the interleaved flyback micro-inverter was chosen as the research object. Secondly, considering that the DC/DC conversion part of the interleaved flyback micro-inverter consists of two identical flyback converters, the work processes of single flyback under discontinuous current mode (DCM) and continuous current mode (CCM) were analyzed. On the basis of the comparison, discontinuous current mode (DCM) was selected as work mode because the control method under DCM was more simple; Then, the work process of interleaved flyback micro-inverter under discontinuous current mode (DCM) was further analyzed. The above analysis were all about hard switching conditions. In practice, at the moment the main switch of flyback converter shut off, the transformer leakage inductance would be resonant with the stray capacitance of the main switch and generate a high voltage which could breakdown the main switch and affect the reliability of the system under a severe circumstance. Therefore, in this paper, the principle of interleaved flyback photovoltaic grid-connected micro-inverter based on active clamp was analyzed in detail. Similar to the process of analysis under hard switching conditions, this paper firstly studied the active clamp process of single flyback micro inverter under discontinuous current mode and proposed an improved work mode. Then, similar process of interleaved flyback photovoltaic grid-connected micro-inverter based on active clamp was analyzed again. Finally, an 220W experimental platform was designed and the designed results were introduced from the aspects of hardware and software design. The relevant theoretical analysis and simulation results were verified on this experimental platform.