Research On Photovoltaic Micro-inverter With Power Decoupling

At present,environmental pollution and energy crisis are two major problems that plague countries in the world,and the development of new energy is imminent.As a clean energy source,solar energy is a research hotspot in the new energy field.The inverter is the key equipment of the photovoltaic power generation system.The photovoltaic micro-inverter is connected with a single photovoltaic module,which can avoid the “wood barrel” effect of the maximum power tracking of the centralized and string inverters.However,the photovoltaic micro-inverter has a poor working environment and there is a problem of secondary power disturbance.The challenge is how to optimize the cost,efficiency,and service life.Focused on the key technical issues of micro-inverters.The research work of this paper is as follows:For the flyback inverter transformer inductor current work in continuous mode,the system is not easy to stabilize the problem,this paper applies intermittent conduction mode,this time the transformer working system is a single pole system,easy to implement system compensation,improve system stability.For the problem of leakage inductance of the flyback transformer,the use of an absorption capacitor provides a channel for the leakage inductance energy feedback,reduces the voltage overshoot on the switch when turned off,and improves the reliability of the circuit.The micro-inverter achieves high energy efficiency conversion through maximum power tracking,but there is a double-frequency fluctuation interference problem in the process of energy conversion.The conventional method is to connect large-value electrolytic capacitors in parallel on the photovoltaic panel side,but the electrolytic capacitor has a short lifetime.For this problem,this paper proposes to add a power decoupling circuit to the system to effectively reduce the capacitance of the decoupling capacitor,and realize the replacement of an electrolytic capacitor by a common thin film capacitor,which greatly improves the reliability and service life of the inverter.For the parallel circuit decoupling method and the decoupling end of the two-stage decoupling method,there is a common part between the decouplingterminal and the photovoltaic terminal(PV terminal),and the operation states of the two ports will interfere with each other.A three-port decoupling method is proposed,and its decoupling port is proposed.Decouple the power independently to avoid affecting the PV port.Based on the study of key technologies,this paper takes a flyback photovoltaic micro-inverter as an example to design the photovoltaic micro-inverter hardware and software with a three-port decoupling circuit,and analyzes the digital control method.Based on this,simulations and experiments were carried out to verify the feasibility of the research work.