A Method Of Power Decoupling For Grid-Connected Photovoltaic Micro-inverters

The energy demand in the word is steadily increasing and the environmental problems caused by the development and utilization of the non-renewable energy are prominent. The new renewable energy has gained more and more visibility. The use of solar photovoltaic power generation is an effective way to solve the energy crisis and environmental pollution problems. The micro-inverter has been more and more widely used because of a number of advantages, such as "Plug and Play" operation, effortless installation, easy system-enlargement, higher energy harvest etc.The PV module generates constant power for maximizing energy harvest controlled by MPPT(Maximum Power Point Tracking), while the power transferred to the grid has a pulsation. Usually, electrolytic capacitors of large capacitance paralleled to PV module 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.The principle of power decoupling is discussed first. And a review of power decoupling technologies is presented. Some magnificent conclusions for power decoupling are drawn.A power decoupling circuit based on flyback converter is proposed. The operational modes of the circuit are introduced. The considerations of circuit design are also discussed. In this thesis, the circuit design and control method are analyzed. According to the discussion, simulation and experiment results are presented to verify the effectiveness of the inverter and power decoupling circuit.Finally, conclusions are drawn and future directions of research are discussed.