Study On Photovoltaic Micro Inverter And Power Optimizer

As the worldwide energy crisis and environment pollution problem increasingly prominent, the use of renewable energy gets more and more attention, in which the solar energy as a new type of green renewable energy has the advantages of large storage, clean and no pollution. For the use of solar energy photovoltaic (PV) power generation technology is one of the most important technologies. Since the middle of1980s, people began to study and use photovoltaic power generation system, until now, a variety of structure of power generation systems has been developed. Different structures have different methods and tendency. Such as the structure of multiple branch type, the string type and master-slave type all suitable for high-power photovoltaic power generation system. With the rapid development of home user and building integrated photovoltaic (BIPV), photovoltaic micro inverter and solar power optimizer (SPO) become more and more popular.This paper mainly studies the photovoltaic grid-connected power generation micro inverter. The interleaved Flyback topology has been chosen as single-phase photovoltaic grid-connected power generation micro inverter of the front-end circuit; Taking the corresponding control strategy, the front-end circuit can achieve maximum power point tracking (MPPT) and half sine output voltage/current with the frequency of1OOHz. The inverter circuit of micro inverter adopts the traditional full bridge inverter circuit without the complex control; grid-connected power generation can be achieved in phase synchrolized with grid. The control loop of micro inverter is similar to the traditional one, which contains the MPPT and current loop. So the control loop of the systerm is simple and efficient. In order to eliminate the imbalance of the input current between the two interleaved paralle circuits, the load balancing compensator has been designed to ensure the balance of the input current between the two circuits.In this paper, it has been analized that the operation principle of bridge type buck-boost circuit is used as the main circuit of SPO. And the parameters of main circuit, control circuit and shaping circuit are designed.Mathematical model of interleaved-parallel Flyback grid-connected micro inverter was established, and verified with the help of Psim simulation software. It is concluded that the design method is feasible. A200W experimental prototype in which dsPIC33FJ16GS504from MICROCHIP Company was selected as CPU to realize the digital control was constructed. Finally, the experimental results show that the micro inverter in this paper implements grid-connected power generation and achieves desired dynamic and steady-state performance. In the paper, The bridge type buck-boost circuit was also simulated by Psim software, and the corresponding control strategy verified. A300w SPO has been developed, in which MC56F8245from FREESCALE Company was seclected as main CPU to realize the digital control. Experimental results show that the SPO have high efficiency and high power density.