Research On An Active-Clamp Flyback-Type Photovoltaic Grid-Connected Micro-inverter With Power Decoupling

In recent years,traditional energy sources such as oil,coal are becoming exhausted and the global energy crisis is imminent.Quick development of renewable energy has become the best way to solve this crisis.Photovoltaic(PV)power generation is one of the most popular technologies in the field of energy and it is paid more attention.Unlike the centralized power grid-connected inverter,PV grid-connected micro-inverter has small size,high efficiency,it has a huge market potential.The PV grid-connected micro-inverter typically uses a Flyback topology,It faces the problems of recycling the leakage inductance energy and instant power imbalance between input power and output power decoupling.The leakage inductance energy dissipation accounts for a large proportion in the system;and affects the micro-inverter efficiency.The voltage stress of main switch in the primary side of the transformer increase due to the voltage spikes caused by the the leakage inductance energy release.The PV module generates smooth output,while the power transferred to the utility grid fluctuates,Usually,large electrolytic capacitors are employed to smooth the input voltage and balance the instantaneous input and output power mismatching.Nevertheless,the lifetime of the electrolytic capacitor becomes the most critical factor that determines the lifetime of the entire system.A PV grid-connected micro-inverter is required to recycle the leakage inductance energy.The circuit topology,operating principle,control strategy and circuit parameter design of an active clamp flyback micro-inverter are discussed in this paper.Power decoupling principle and some power decoupling circuits are discussed,a DC-DC converter is selected to realize the power decoupling.Simulation results in PSIM software show the feasibility and rationality of the parameter design and the control scheme,and a 100W PV grid-connected micro-inverter prototype is developed.The experimental results show that this kind of inverter has the advantages such as active clamp,power decoupling.The expected target of the system is achieved.