Research On Control Scheme Of Interleaved Flyback PV Micro-Inverter

With the rapid development of global economy, the consumption of current non-renewable energy resource is becoming more and more seriously. In order to solve this problem, how to reasonable development and utilization of renewable energy has been the key point that governments and researchers focus on. Solar energy as a clean and renewable energy, grid connected photovoltaic system based on basic principle of photoelectric conversion has become an effective means to solve the future energy crisis. The current photovoltaic industry is developing rapidly, photovoltaic grid micro-inverter, which applied in distributed generation with its high efficiency, small volume and high reliability has been widely used in small and medium distributed occasions. Paper briefly presents the development of photovoltaic power generation, and the grid connected photovoltaic micro-inverter is discussed. It presents the research direction and emphasis of domestic and foreign manufacturers, experts and scholars in this field. And the research focuses on the active clamp interleaved flyback photovoltaic micro-inverter.This paper mainly discusses the control strategy of active clamp interleaved flyback photovoltaic micro-inverter. Firstly, the merits of the three working patterns are compared, which includes continuous current mode (CCM), boundary conduction mode (BCM) and discontinuous conduction mode (DCM). Then, BCM/DCM mixed digital control scheme is put forward for micro-inverter, and high efficiency performance is achieved over a wide range variation of power output. This paper analyzes the basic principle of power circuit, and discusses the core concept of strategy realization. Furthermore, in order to reduce the design cost of micro-inverter, this paper applied a current sensorless maximum power point tracking (MPPT) control strategy in it.This paper presents a 200W experimental prototype of active clamp interleaved flyback micro-inverter. The important parameters of power circuit, and control circuit are analyzed and described in detail. Through the simulation of micro-inverter, the results verified the feasibility of full digital control and current sensorless MPPT strategy. Moreover, power losses of micro-inverter are calculated, which proves using the above method has higher working efficiency. A 200W photovoltaic grid-connected flyback micro-inverter experimental prototype is made, and aforementioned control schemes are applied. Finally, the experimental results of micro-inverter verified the correctness of the design.