Efficiency Evaluation Of Interleaved Flyback Micro-inverter

Compared with the centralized or string type photovoltaic inverter, Micro-inverter has strong ability of anti partial shade, each Micro-inverter harvests optimum power. At present, the conversion efficiency of Micro-inverter is still lower than the centralized or string type photovoltaic inverter, How to increase the efficiency of the Micro-inverter is critical to increase the penetration of it. This thesis focuses on the efficiency optimization of Interleaved Flyback Micro inverterIn the first chapter, we compare the Micro-inverter with conventional inverters, then introduce current situation and development of Micro-inverters.The working principle, control strategies and parameters design of Flyback Micro-inverter are introduced in the second chapter. Transformer is the most important device in Flyback circuit and design of Flyback transformer is introduced in detail. Base on the analysis, we do the simulation by using the simulation software Psim.The third chapter discuss the efficiency evaluation of Micro-inverter. Loss models are established to analyze the main source of loss. The effects of power devices, switch frequency and transformer parameters on efficiency are discussed. In the optimization of power devices, we compare the efficiency between using SiC devices and Si devices. In the optimization of Flyback transformer, magnetizing inductance and leakage inductance are optimized to achieve higher efficiency. And we also compare the efficiency under different switching frequency. Base on the theoretical analysis, a200W prototype is built and the experiment result is compared with the theoretical result.The fourth chapter is summary and prospect of this thesis.