Flyback-Type Grid-connected Photovoltaic Micro-inverter With Power Decoupling Techniques

With the situation of energy resource crisis and the problem of circumstance pollution becoming more and more severe, the most ideal resource is solar, for its main features, which include non-polluting and resource infinity. So its mass exploitation would be inevitable. Photovoltaic solar energy utilization in the most likely research, usually used AC power, therefore, photovoltaic grid-connected power generation becomes a major trend with broad prospects.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. The primary tasks of this study are as follows:(1)Three different modes of power decoupling:①PV side decoupling;②DC link decoupling;③AC side decoupling.(2)Analysis of decoupling capacitor charging and discharging operation.(3)The hardware circuit of the controlling system is designed including the main circuit, control circuit and drive circuit etc.(4)The experimental setup for grid-connected inverter system is constructed; the experiments were carried out in detail.(5)Finally, conclusions are drawn and future directions of research are discussed.