Research On Grid-Connected Micro-inverter Based On Interleaved Flyback Topology

Nowadays, with the increasing severity of energy depletion and environmental pollution, the sustainable development of the energy is gaining more and more attention, and the use of solar energy has become the field that the world are scrambling to develop. As the core device of the solar power system, inverter plays a vital role in the development and using of photovoltaic technology. For the shortcomings of traditional centralized inverter, such as power loss, hot pots caused by partial shade covering and inflexible expansion, a new type of grid-connected photovoltaic power generation called micro-inverter has been put forward which is based on each PV module.This paper summarizes the topologies of micro-inverter, analyzes its principle, advantages and disadvantages, and then chooses the topology of interleaved flyback photovoltaic grid-connected micro-inverter as the object of study. Based on the operation principle of flyback inverters under discontinuous current mode(DCM)、 continuous current mode(CCM) and boundary current mode(BCM), a comparative look from control strategies and key parameters is presented which is proved by Matlab simulation and could provide a reference for selecting operation mode according to the design requirements. Then, this paper chooses a micro-inverter under continuous conduction mode at a rated power of 220W as the object of study, gives out detail design method of power circuit. Based on the small signal AC model of micro-inverter, a feed-forward compensator is put forward to improve the response speed of the system, a load sharing compensator is designed which could ensure equal sharing of the injected current to enhance the reliability of the system. Meanwhile, in order to maximize the output power of PV module and guarantee the safety of grid-connected system, maximum power point tracking method and anti islanding control strategy has been put forward for micro-inverter. Finally, gets the components of micro-inverter losses based on the loss analysis, and active clamp technique is introduced. The detailed analysis and basic design consideration will been given to illustrate the principle of operation, and the simulation results are agree with the theoretical analysis.